Ph.D. - Horticulture

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Genetic Improvement of Leucaena Spp. and Acacia Koa Gray as High-Value Hardwoods
(University of Hawaii at Manoa, 2003) Shi, Xuebo
Studies on genetic improvement of Leucaena and Acacia koa Gray were undertaken in Hawaii from 1999-2003. There studies were described in two sections. The first section focused on research of Leucaena hybrids, which included vegetative propagation of Leucaena hybrids, hybrid yield trials, and chromosome doubling of diploid Leucaena species. Different hybrids rooted differently. Cuttings with more leaf presence had higher rooting frequency, better root qualities, and quicker root initiations. Leafless cuttings did not root under a mist system. One-node cuttings rooted as well as bi-nodal cuttings. Cuttings from younger (25-45 days old) regrown shoots rooted better than cuttings from older shoots (>45 days old). All hybrids rooted poorly in winter. Difficult-to-root hybrids rooted well after the treatments of etiolation. Three hybrid yield trials using clones of hybrids were carried out at three locations, Waimanalo of Oahu, and Hamakua and Kona of Hawaii Island. Seedless hybrid KI 000 grew best at warm areas of Waimanalo and Kona, but grew poorly at cool area of Hamakua in terms of DBH, height, and wood volume. Two tetraploid hybrids, KX3 cl2 (L. leucocephala x L. diversifolia) and K I56 x K376 (L. diversifolia x L. pallida) were among the fastest-growing hybrids at Waimanalo and Hamakua. The method (0.1% colchicine treatments on seedlings) to induce tetraploid Leucaena species was effective. Larger, thicker and darker leaflets, and larger flower heads of induced tetraploids were observed. The second section focused on studies of koa, which included cytological study of koa, vegetative propagation, koa mortality and tolerance to wilt disease, and prediction of breeding values of koa. No variations in chromosome number were found among three koa types and populations. The chromosome number of koa was identified as 2n=52 among all populations examined. Koa vegetative propagation was feasible at juvenile stage. Rooting ability of cuttings declined quickly with the increase of the age of cuttings. Cuttings of most families did not root at transitional and mature stages, and they did not respond to the treatments of growth regulators. Only cuttings of two families from Hawaii Island responded to auxins well with a moderate increase in rooting percentage at transitional and mature stages. Etiolation treatments appeared to have some effects on rooting at transitional stage. Koa survival rates in progeny trials declined steadily over the years. The mortality appeared to be mainly caused by koa wilt disease. The survival rates of koa families were analyzed and used to assess family tolerance to the disease. Great variation in survival rate was found among the families. Family selection based on survival rate was conducted. To rank the growth performance of koa families in progeny trials, breeding values of DBH at the age of 4 years were predicted in 4 progeny trials using BLP (Best Linear Prediction) method. Family ranking and selection based on predicted breeding values were conducted. Genetic gains of selection were calculated based on family selection.
Source-sink Relationship During Papaya Fruit Development and Ripening
(University of Hawaii at Manoa, 1999) Zhou, Lili
The source sink relationship during papaya fruit development and ripening was investigated. The source size and sink strength were modified by single or continual defoliation, and fruit thinning, respectively. The relationship between fruit growth, respiration, sugar accumulation and the activity of sucrose phosphate synthase (SPS), sucrose synthase (SS), and acid invertase were determined in fruit from 14 days after anthesis (DAA) to 140 DAA (harvest maturity) and in response to defoliation and fruit removal. A putative complete invertase gene and a SS gene fragment were isolated and characterized from nearly mature green papaya fruit. Single defoliation significantly reduced new flower and fruit set, and ripe fruit total soluble solids (TSS) but did not reduce fruit production, average fruit mass, percentage fruit flesh and seed, seed mass ratio and seed dry mass during a six weeks period. Continual defoliation in addition reduced fruit size, sugar and invertase enzyme activity and fruit production. The responses of defoliation and fruit thinning varied between different cultivars, weather conditions, defoliation time, degree and method. The pattern of gene expression during fruit development was compared with invertase extracted enzyme activity in the presence and absence of sodium chloride (NaCI) and by western blot analysis. The papaya invertase sequence had an open reading frame that encoded a polypeptide chain of 582 residues and calculated molecular weight of 65, 684 Da. The protein was highly homologous to known plant cell wall invertase and 67% identical at the amino acid level to carrot cell wall invertase. The cloned 720 bp SS fragment was highly homologous to A. glutinosa (X92378) and SS genes from other species. Invertase gene was expressed at a higher level during late fruit development stage than in young fruit and other tissues of papaya plant. SS gene expression was higher in young fruit and petiole tissues than in other tissues. The data demonstrated that SS enzyme was a major enzyme in fruit sink establishment and maintenance. Apoplastic invertase had an important function in phloem unloading during papaya fruit sugar accumulation and the activity was regulated at both transcriptional and translational levels.
Breeding for Papaya Ringspot Virus Tolerance in Solo Papayas, Carica papaya L.
(University of Hawaii at Manoa, 1985) Zee, Francis T.P.
A high degree of Papaya Ringspot Virus (PRV) tolerance was observed in a dioecious Carica papaya, line 356, introduced from Florida. Upon infection with the virus, plants of line 356 produced mild leaf, stem and fruit symptoms. Fruit distortion was not observed on these plants. Selected females of line 356 were crossed with 'Kapoho', 'Higgins' and 'Waimanalo' to produce lines 402, 410 and 403, respectively. The level of virus tolerance in these hybrids was observed to be intermediate between the 356 and solo parents. A few selected F2 plants had significantly higher PRV tolerance than the solo parents and only a few trees produced distorted fruits. The F2 plants from 402DF1 and 410AF1 were more tolerant to PRV than 403F1 and derived F2's. Selected 410AF2 trees had the highest virus tolerance among the hybrids but fruit quality was unacceptable. The 402DF2 plants were intermediate in virus tolerance, but produced fruits with good eating quality. The cool climate at the Olinda station in Maui provided good growing conditions for 5 wild Carica species and one interspecific hybrid, but did not permit successful interspecific hybridization between Carica papaya and other species. Carica papaya was crossed with C. pubescens, C. monoica and a C. cauliflora x C. monoica hybrid, resulting in fruits with a few seeds, but no viable hybrid plant was produced. The extraction buffer for C. papaya in ELISA was not suitable for PRV detection in other Carica species. Leaf homogenates from C. pubescens and microcarpa were observed to have a certain compound that interfered with PRV detection when mixed with a PRV standard. The higher the concentration of pubescens homogenate in the mixture, the higher the interference effect. This interference compound appeared to interfere with the PRV-y-globulin, is not protein specific and can be destroyed by heat.
Herbicidal Activity and Translocation of Glyphosate in Cyperus Rotundus l.
(University of Hawaii at Manoa, 1976) Zandstra, Bernard Henry
Purple nutsedge (Cyperus rotundus L.) plants grown in the greenhouse were treated with 4 kg/ha glyphosate [N-(phosphonomethyl) glycine] or 2.2 kg/ha paraquat (1,1'-dimethyl-4,4'-bipyridinium ion). Glyphosate greatly reduced fresh weight of leaves, number of sprouts per original tuber, and number of sprouts per new tuber. Paraquat reduced fresh weight of leaves about as well as glyphosate, but was not as effective in reducing germination of tubers. Glyphosate at 2 and 4 kg/ha was compared in the field to paraquat, dicamba (3,6-dichloro-o-anisic acid), and MSMA (monosodium methanearsonate) for purple nutsedge control in repeated applications over 8 months. After two applications glyphosate had greatly reduced the number of plants. The other herbicides were not as effective in reducing number of shoots. At 5 months, after the field was rotovated and herbicides reapplied, glyphosate and MSMA gave better control of purple nutsedge plants than the other herbicides. Glyphosate and MSMA also reduced germination of tubers from treated plants. After five applications, glyphosate and MSMA reduced germination by 70%, and dicamba reduced germination by 43%. Paraquat did not reduce germination. Since glyphosate gave good control of purple nutsedge, further studies were conducted to determine the most effective rate of glyphosate, and the most susceptible age of purple nutsedge at application. Purple nutsedge was treated with glyphosate at 2, 4, 6, 12, or 24 weeks after field preparation. Glyphosate was reapplied at 2, 4, 6, or 12 week intervals, respectively, until no shoots emerged. Plants were counted in treated plots every 2 weeks, and tubers were dug every 4 weeks. These tubers were germinated to test viability by placing them in Petri dishes and incubating with 100 ppm N-6 benzyl adenine. All purple nutsedge plants treated at 12 weeks old were killed by glyphosate at 2 and 4 kg/ha, as evidenced by no regrowth of shoots, and almost no germination of tubers. Control of purple nutsedge in plots treated at 2 to 6 weeks old was less effective and several applications of glyphosate were needed to achieve good control levels. Application of glyphosate at 24 weeks killed purple nutsedge foliage, but new growth emerged immediately. Generally, application of glyphosate every 2 weeks reduced plant numbers more rapidly than every 4 or 6 weeks. Rates of 1, 2, and 4 kg/ha were equally effective in reducing number of plants after several applications, but 2 and 4 kg/ha were more effective with fewer applications. Two kg/ha gave as good control as 4 kg/ha. Viability of tubers from plants treated at 2 to 6 weeks old was higher than of tubers from plants treated at 12 weeks old. Applications of glyphosate at 24 weeks did not reduce viability of tubers. The field was rotovated 10 months after the initial preparation, and the purple nutsedge allowed to regrow. Regrowth was rapid in all plots. However, all plots treated with glyphosate except those treated at 24 weeks, produced less regrowth than the controls. Succeeding experiments carried out in the greenhouse further examined the effects of age and stage of purple nutsedge growth on its control with glyphosate. Tubers from purple nutsedge plants grown in the greenhouse for 2 to 10 weeks did not germinate after foliar application of glyphosate. Some tubers from, plants 12 and 24 weeks old survived glyphosate application. 14C-glyphosate was used to study translocation of glyphosate in 1-to 6-week-old purple nutsedge plants. Translocation of –glyphosate from treated leaves increased from 5% of the amount applied at 1 day to 19% at 4 days after application. Specific activity of in tubers was greater than in leaves at all growth stages. With increasing plant age, specific activity decreased in both tubers and leaves. Also with increasing plant age, total translocated increased in tubers, and decreased slightly in leaves. Thin layer chromatography showed no evidence of glyphosate metabolism in purple nutsedge. These results indicated that stage of growth is an important factor in obtaining control of purple nutsedge with glyphosate. Purple nutsedge in the field was most susceptible 12 weeks after the field was prepared. Purple nutsedge grown in the greenhouse was most susceptible at 2 to 10 weeks after planting. Evidently the stage of growth, or physiological age of the plant, is more important than chronological age. Once purple nutsedge plants have flowered, senescence sets in, and effectiveness of glyphosate declines.
Ovule and Ovary Culture in Doritis Pulcherrima
(University of Hawaii at Manoa, 1980) Yasugi, Saburo
Pollination resulted in an increase in size of ovary, the development of the ovules and fertilization in Doritis pulcherrima. The growth curve of percentage increase in total growth of ovary width was bimodal. The first dip was at 40 days after pollination which was correlated with the time of megaspore formation inside the ovary. The growth curve of increase in percentage of ovary length was trimodal. These growth curves did not show a strong relationship with the development of ovule and embryo. However, the incremental growth in width and length of ovary was highest during rudimentary ovule formation and before embryo sac maturation. The mature pod dehisced at about 210 days after pollination, while the incremental growth in width and length stopped at about 90 to 110 days after pollination. Wilting of perianth occurred 2 days after pollination, which is the first observable morphological change in Doritis. The placental ridge started to proliferate at about 20 days after pollination. Approximately 60 days was required to form the mature embryo sac and almost half of that time was occupied in placental growth. Although the pollen tubes existed around developing ovules at 10 days after pollination, they entered the micropyle after the embryo sac was fully formed at about 60 days after pollination. Fertilization occurred soon after the embryo sac was fully formed containing mature egg at 60-65 days after pollination. Therefore, approximately 1/4 of the period between pollination and pod maturity was required for fertilization. Between 40 to 50 days after pollination, the megaspore mother cell underwent meiosis. After the first division, the two dyads were formed, and after the second division two megaspores and the degenerating dyad was formed. The megaspore enlarged and formed the 8-nucleate embryo sac at about 60 days after pollination. At about 65 days after pollination, the zygote and the endosperm initial cell were formed through double fertilization. However, the endosperm initial cell degenerated soon thereafter. At about 70 days after pollination, the zygote divided to form a 2-celled embryo which consisted of a terminal cell and a basal cell. Thin middle and suspensor initial cells were produced from the basal cell. The seed coat was also formed at about 70 days after pollination from the integuments. At about 80 days after pollination, the suspensor initial cell produced eight suspensor cells, and the terminal cell produced a multi-celled embryo. Histochemical study showed that deoxyribonucleic acid (DNA), ribonucleic acid (RNA), total proteins and total carbohydrates decreased during megasporogensis. An interesting point was that RNA was more dense in the terminal cell than in the basal cell, which suggested that the initial differentiation had already occurred in the 2-celled embryo This is the first case of obtaining seedlings of orchids directly from ovules through ovary and ovule culture with ovules collected prior to the occurrence of fertilization. Approximately 150 days were reduced to obtain seedlings of Doritis pulchcrrima from pollination through ovary and ovule culture over the traditional method of sowing "mature" seeds. Seedlings were obtained from ovules 45 days prior to normal fertilization time through ovary and ovule culture, which suggested that fertilization must have occurred in vitro during ovary and ovule culture to obtain seedlings. In the 20-day-old ovule culture, young seedlings were obtained from the treatments of sucrose; naphthaleneacetic acid (NAA) + coconut water; and NAA + 6-benzlaminopurine (BA) + coconut water. However, the growth rate of ovules during culture was not high in these treatments. In the 40-day-old ovule culture, the treatments of sucrose; coconut water; and NAA + BA + sucrose + coconut water were highly effective on both ovule growth rate and seedling formation. In the 60-day-old ovule culture, seedlings were obtained from all treatments except NAA; BA; and NAA + BA. Good growth of ovules did not always induce good seedling formation. Seedlings were obtained from 20-, 40- and 60-day-old ovule cultures if media contained sucrose or coconut water. Sucrose must be necessary for seedling formation during ovule culture, since coconut water contains sucrose. However, if we compare the time required to obtain seedlings, coconut water promoted faster growth than sucrose alone in ovule culture. Maleic hydrazide, tryptophan, casein hydrolysate, NAA and BA were not effective on seedling formation without sucrose or coconut water. The best hormonal conditions for obtaining seedlings in ovary culture were 1.0 ppm BA in 20-day-old ovary culture, 1.0 ppm NAA in 40-day-old ovary culture, and 1.0 ppm NAA in 60-day-old ovary culture. BA was more effective than NAA in forming seedlings in early stage (20 days after pollination) during ovary culture. Coconut water was also effective in ovary culture to obtain seedlings. However, it also increased callus formation rate. Sucrose was necessary in ovule culture to obtain seedlings. However, even without sucrose seedlings were obtained through ovary culture with NAA or BA treatments. Therefore, sucrose might be necessary for ovule development and seedling formation, but in the case of ovary culture sucrose might be obtained from the ovary wall tissues. Sucrose was also necessary for seed germination, but coconut water can be substituted effectively for seed germination and protocorm formation. Sucrose appears to have a very important role in ovule and embryo developments and seedling formation.
Productivity of Vegetable Crops Grown under Shade in Hawaii
(University of Hawaii at Manoa, 1988) Wolff, Xenia Yvette
Waimanalo Long' eggplant (Solanum melonaena L.), 'Kahala' soybean ^Glvcine max (L.) Merrill), 'Jumbo Virginia' peanut (Arachis hvpoaea L.), 'Waimanalo Red' sweet potato flpomea batatas (L.) Lam.), and 'Green Mignonette' semihead lettuce fLactuca sativa L.) were field-grown in two seasons at Waimanalo, Oahu, Hawaii with five artificially produced levels of shade (0, 30, 47, 63, and 73%). Yields and vegetative growth of eggplant, soybean, peanut, and sweet potato were linearly decreased with increasing shade levels. Compared to unshaded controls, yields of semihead lettuce increased significantly from 8100 kg•ha-1 to 13,600 kg•ha-1 by 30% shade in Fall 1986. During Spring 1987, semihead lettuce yields were reduced only slightly from unshaded levels of 22,000 kg•ha-1 by increasing shade up to 47%. Eggplant, soybean and lettuce maintained index leaf areas similar to unshaded controls as shade intensity increased, at the expense of leaf dry weight. By comparison, both leaf area and leaf dry weight of peanut index leaves decreased as shade increased. Leaf area and leaf dry weight of sweet potato did not respond to shading. To further investigate the effects of shade on leafy vegetables, 'Green Mignonette', 'Salinas', 'Parris Island Cos', and 'Amaral 400' lettuce (Lactuca sativa L.), 'WR-55 Days' Chinese cabbage (Brassica raoa L. Pekinensis Group), 'Waianae Strain' green mustard cabbage (Brassica iuncea (L.) Czerniak), 'Tastie Hybrid' head cabbage (Brassica oleracea L. Capitata Group), and an unnamed local selection of bunching onions (Allium ceoa L. Aggregatum Group) were field-grown in two seasons at the same location with the same five artificially produced levels of shade. Yields of cos lettuce, green mustard cabbage, and bunching onions were irresponsive or negatively affected by shade in both seasons. Yield responses of the other crops to shade varied seasonally. Optimum shading of 30 to 47% increased 'Green Mignonette', 'Salinas', and 'Amaral 400' lettuce by 36% and head cabbage and Chinese cabbage yields by 23% and 21 %, respectively, compared to full-sun plots in some trials. Index leaf areas similar to unshaded controls were maintained as shade intensity increased, at the expense of leaf dry weight in all crops except 'Salinas' and 'Parris Island Cos' lettuce. Maximum rates of net photosynthesis (Pn) were attained at about two-thirds of full sunlight (1500 umol • s-1•m-2).
Ammonium Sulphate Enhancement of Picloram Herbicidal Activity and Absorption in Two Guava Species and Dwarf Beans
(University of Hawaii at Manoa, 1974) Wilson, Bruce James
Studies were conducted to increase picloram herbicidal activity on guava (Psidium guajava L.), strawberry guava (Psidium cattleianum Sabine) and dwarf beans (Phaseolus vulgaris L. cv. Bountiful) using ammonium sulphate as an adjuvant, and to determine the basis for the enhancement effect. Guava and strawberry guava seedlings were grown in pots outdoors for 3 to 4 months and 4 to 5 months respectively, and subsequently in the glasshouse for 2 months, before treatment with picloram alone at 0.25 , 0.50 and 0.75 kg a.i. /ha, or plus ammonium sulfate at 0.10, 0.75, 1.0 and 10% (w/v). Dwarf beans were treated with picloram alone at 0.02 and 0.04 kg a.i. /ha, or plus ammonium sulfate at 0.10, 0.50, 1.0, 5.0 and 10% (w/v). Ammonium sulfate increased picloram herbicidal activity in all three species to varying degrees, depending on picloram rate and ammonium sulfate concentration. Picloram injury was enhanced by ammonium sulfate at all picloram rates shortly after treatment. The higher picloram rates continued to increase injury with time, so that by the end of the experiment on each species, the maximum effect was attained without ammonium sulfate and an- enhancement effect could not be demonstrated. The enhancement effect remained evident at the low picloram rates. Ammonium sulfate concentrations of 0.75% to 1.0% and higher were equally effective at increasing picloram activity at the end of each experiment, but at earlier times, picloram activity increased with increasing ammonium sulfate concentration up to 10%. Paired leaves on the upper stem of strawberry guava and guava seedlings were treated with 14C-picloram alone or plus ammonium sulfate at 0.5% and 10% (w/v) on strawberry guava, and 0.5$ on guava. The 14C-picloram acid was converted to the potassium salt using commercial formulation blank, so that the 14C solutions were equivalent to the picloram solutions used in the activity experiments. After 2 days on strawberry guava, 0.5% ammonium sulfate increased 14C-picloram absorption about five-fold. There was about four times more 14C in the upper stem and attached leaves with ammonium sulfate added than with picloram alone. 14C-picloram absorption from 0.5% and 10% ammonium sulfate treatments was equal. Ammonium sulfate at 0.5% increased picloram absorption by four-fold in guava, but there was no increase in the amount of 14C translocated. All the 14C in both guava species was shown to be 14C-picloram by paper chromatography of extracts. Picloram absorption by dwarf beans, measured by difference between the amounts of picloram applied and the amount recovered, was increased by 0.5% and 10% ammonium sulfate by a similar magnitude as on guava species. Picloram absorption was further studied using detached strawberry guava leaves, and guava leaves in an initial experiment. 14C-picloram absorption was greater through the lower surface than through the upper surface, with or without ammonium sulfate. In strawberry guava leaves, 14C-picloram absorption through the upper and lower leaf surfaces was equal, but the ammonium sulfate enhancement of absorption was much greater through the upper surface. Ammonium sulfate increased the rate of 14C-picloram absorption, but absorption from 14C-picloram alone or plus ammonium sulfate levelled off at 6 to 12 hours. The magnitude of the ammonium sulfate-induced increase in 14C-picloram absorption was not affected by picloram concentration in the range 250 to 2000 ppmw, or by leaf age. 14C-picloram absorption by this detached leaf method was highest at an intermediate ammonium sulfate concentration range, such that absorption with 0.1% and 10% ammonium sulfate was less than with 0.5%; 0.01% had no effect on absorption. Increased 14C-picloram absorption resulted from adding the ammonium salts of sulfate, nitrate, chloride or dibasic phosphate, but not from ammonium carbonate or ammonium molybdenate. Ammonium sulfate was the only one of six sulfate salts tested to increase picloram absorption. pH adjustment of the external solution from 6 to 4 increased picloram absorption, while a pH change from 6 to 8 had no effect. In buffered solution at pH 4 ammonium sulfate did not increase 14C-picloram absorption. Ammonium dibasic phosphate at a solution pH of 7.7 increased picloram absorption as effectively as ammonium monobasic phosphate at pH 4.6. Potassium monobasic phosphate at pH 4.6 increased absorption to about one-half the value with ammonium phosphates added, whereas potassium dibasic phosphate at pH 9.5 had no effect. Stomata are not present on the upper surface of strawberry guava leaves, thus in the measurement of the effect of ammonium sulfate on picloram absorption, cuticular penetration of picloram must have been involved. The evidence suggests that ammonium sulfate has a direct physical effect in the absorption pathway.
Genome and Karyotype Relationships in the Genus Dendrobium (Orchidaceae)
(University of Hawaii at Manoa, 1968) Wilfret, Gary Joe
Investigations on sexual compatibility, karyotype analysis, and genome relationships were made with species in the genus Dendrobium of the family Orchidaceae. A hybridization study was made utilizing 38 species of 10 taxonomic sections in 48 combinations. A total of 783 pollinations was made with 164 fruits harvested, of which 113 produced viable crosses. Five intrasectional and 20 intersectional combinations resulted in viable seedlings. The Eugenanthe x Eugenanthe combination showed little compatibility among the species within the section and showed equal or more compatibility with the Ceratobium, Phalaenanthe, and Pedilonum sections. Species in the Ceratobium section crossed as readily with species in the Phalaenanthe section as within the Ceratobium section. The percentage of non-aborted embryos was determined for each fruit harvested. The separation of all the species into the classical taxonomic sections of the genus was not possible on the basis of their cross ability or percentage of non-aborted embryos. Chromosome numbers of 33 species in 11 sections were determined, of which 31 were 2n=38 and 2 were 2n=40. Five of these had not previously been reported. Detailed examinations of chromosome morphology were made of 23 species in 11 sections. The mean chromosome size was as variable within the sections as between the sections. The sections could not be distinguished-by the average chromosome length of their constituents. No relationship was found between chromosome size and geographical and climatological distribution in the species studied. A mean S% and F% for each species and the average for each section was calculated. Individual sections could not be distinguished on the basis of S% and F7» although a few individual species could be detected by these values in conjunction with other morphological characteristics of the karyotypes. The evolution of the karyotypes was not reflected in the external morphological specializations of the sections. Meiosis in four intrasectional Ceratobium hybrids consistently showed 19 bivalents and the products of meiosis were normal tetrads with 19 chromosomes distributed to each microspore. Five intersectional Phalaenanthe x Ceratobium hybrids displayed an average of 16.80 bivalents and 4.40 univalents. Microspore division exhibited an average of 93.2% tetrads and 3.9% dyads, with tetrads and dyads with microcytes also observed. Meiosis in a Phalaenanthe x Latourea hybrid showed 2.06 bivalents and 33.88 univalents with the products of meiosis being tetrads, dyads, and tetrads and dyads with microcytes. Heterochromatic and heteroraorphic bivalents were observed in the intersectional hybrids. The results indicated that the genomes within the Ceratobium are closely homologous; the genomes of Ceratobium and Phalaenanthe are closely related; and the genomes of Latourea are more closely related to Ceratobium than Phalaenanthe.
Influence of Vesicular-arbuscular Mycorrhizae on the Growth and Water Relations of Vegetable Crops
(University of Hawaii at Manoa, 1988) Waterer, Douglas R.
Onion, leek, pepper, lettuce and tomato transplants grown in a soilless medium inoculated with the VAMF Glomus aggregatum (Schenck and Smith emend. Koske) were larger and had higher tissue phosphorus (P) concentrations than non-inoculated plants if P levels in the medium were low. At higher P concentrations, inoculation had little or a slightly negative effect on transplant growth. Increasing P concentrations in the medium increased transplant growth, but decreased root infection by the VAMF. Increasing VAMF inoculvim concentrations did not affect growth or P uptake but increased VAMF infection of the transplants. Daily application of low P fertilizer solutions produced larger transplants with more extensively infected root systems than did similar amounts of P supplied less frequently but at higher concentrations. Different crops required different combinations of P concentration and application interval to produce vigorous mycorrhizal transplants. The controlled-release fertilizer Osmocote (Sierra Chemical Co., Milptas Calif.) produced predictable and stable solution P concentrations in the soilless medium used for transplant production. Growth and VAMF infection of the transplants could be manipulated by altering Osmocote P concentrations in the transplant medium. Pre-transplant inoculation of peppers subsequently planted into P deficient soil improved early P uptake, vegetative growth and total fruit yields relative to plants inoculated at transplanting. In P deficient soils, maximum pre-transplant VAMF infection of peppers increased subsequent growth and fruit yields more than maximum pre-transplant growth. Extensive pre-transplanting infection improved post-transplant P uptake earlier than in less heavily infected plants. In contrast, pre-transplant growth of lettuce was more important than mycorrhizal infection in determining subsequent growth, at all soil P levels. In pots, G. aggregatum increased total dry matter yields, promoted early fruit set and improved fruit yields of peppers at solution P concentrations below 0.3 to 0.4 mg/liter. At higher P concentrations, VAMF infection had no beneficial or harmful effects. Tissue P requirements for dry matter production by mycorrhizal plants were lower than in non-mycorrhizal plants, suggesting that mycorrhizae may influence the efficiency of utilization of absorbed P in addition to increasing P uptake efficiency. In the field, inoculation of peppers increased tissue P concentrations, growth and fruit yields by 28, 120 and 350% respectively relative to non-mycorrhizal plants in a fumigated P-fixing soil with 0.03 mg/liter solution P. Inoculation had no significant effect at 0.30 mg P/liter. Under similar conditions, VAMF infection increased yields of lettuce by 16%. Although non-mycorrhizal lettuce and peppers had similar solution P requirements for maximum growth, lettuce was more tolerant of sub-optimal solution P concentrations and was correspondingly less responsive to infection by the VAMF. Moderate water stress increased mycorrhizal responsiveness of peppers growing in P deficient soil. VAMF colonization of pepper seedlings growing in P deficient media increased the hydraulic conductivity of their roots, possibly by improving seedlings tissue P status. Mature mycorrhizal peppers had higher rates of transpiration per unit leak area than similar size non-mycorrhizal plants. At wilting, mycorrhizal transplants and mature peppers had higher leaf water potentials at lower soil water potentials than non-mycorrhizal plants. The influence of mycorrhizae on the water relations of mature peppers was apparently related to the mycorrhizae improving P uptake by their host but the change in water relations of inoculated seedlings was generally independent of host P-status.
Biochemical and Genetic Analyses of Lavender-purple Spathes in Anthuriums
(University of Hawaii at Manoa, 1988) Wannakrairoj, Sura Wit
Systems controlling lavender-purple spathe color in anthuriums were investigated biochemically and genetically. Regression analysis of biochemical data showed that the blueness of anthurium spathe color was the result of cyanidin 3-rutinoside and its interaction with cell sap pH and major flavonoids from A. amnicola, A. andraeanum and A. antioouense. The ratio of cyaniding 3-rutinoside to acacetin C-diglycoside was found to be the most important factor determining the degree of blueness in the regression model. Results from in vitro copigmentation experiments suggested that the inhibition effect of acacetin C-diglycoside may be due to some unknown factors strongly associated with the flavone. A. amnicola and A. antiocfuense of section Porphvrochitonium, and A. andraeanum and A. formosum of section Calomystrium were shown to be closely related based on their crossability and on the meiotic behavior of hybrids. All interspecific hybrids showed 15 bivalents at metaphase I; however, some hybrids showed spindle abnormalities. Interspecific progenies of A. amnicola produced the lowest percentage of viable pollen. A genetic scheme controlling lavender-purple spathe color was proposed. The system consisted of two loci controlling red-orange-white colors and a recessive epistatic locus for the copigmentation inhibitor. General combining ability of parental species for the quantity of the factors involved in color expression was determined.
The Genetics of Flowering Time in Raphanus Sativus L. Cv. 'Chinese Daikon'
(University of Hawaii at Manoa, 1969) Vahidy, Ahsan Ahmad
The Inheritance of Photoperiodism in Snap Bean (Phaseolus Vulgaris)
(University of Hawaii at Manoa, 1977) Tsao, Shing-jy J.
The heredity of photoperiodic response of flowering in Phaseolus vulgaris was studied. The parents were classified into three types according to their photoperiod sensitivity— day-neutral (flower at any daylength), intermediate (require a night longer than 11.5 hours), and sensitive (require a night longer than 12 hours). Crosses between parents of the same phenotype generally produced F1 and F2 progenies which showed no segregation. The segregation patterns for photoperiodic response were determined for larger numbers of individuals by planting during the summer when days are too long for floral induction and assuming that each plant begins to flower when the daylength has shortened to the critical length required by that plant. Temperatures within the range experienced in the field were found to have an insignificant effect. It is postulated that the inheritance of the photoperiodic response in these lines is determined by at least four major gene loci with dominance, epistasis, and independent segregation. A dominant N gene is postulated that permits flowering at any daylength. If the recessive n gene or a dominant inhibitor of the N gene, IN , are present, there is an intermediate daylength requirement for flowering. A dominant Q gene which intensifies the short daylength requirement is also postulated. If the recessive q gene or a dominant inhibitor of the Q gene, IQ, are present, the daylength requirement again is of the intermediate type. The day-neutral and intermediate parents therefore differ by two genes (at the N and IN loci), and the intermediate and sensitive parents differ by another two genes (at the Q and IQ loci), so that the day-neutral and sensitive parents differ by a total of four genes. It is likely that additional genes with smaller effects may also be involved.
Strategies for Machine Harvesting of Mature Coffee (Coffea Arabica L.) Fruits
(University of Hawaii at Manoa, 1993) Tongumpai, Peeradet
Greenhouse and field grown coffee plants were used to study the synchronization of flowering and fruiting. The purpose of these studies was to develop methods of improving the selective harvesting of mature coffee fruits by machine. The studies were divided into 4 parts: 1) Synchronization of flowering, 2) Synchronization of fruiting, 3) Determination of fruit detachment and fruit removal force (FRF), and 4) Alteration of the FRF of ripe fruits. Either mist irrigation or water deficit stress followed by sufficient watering were effective in inducing flowering. Gibberellic acid treatment was less effective. Gibberellic acid applied to field grown coffee plants with fruit at different ages up to 40 days after anthesis advanced fruit maturity but did not synchronize fruit maturation. Ethephon sprayed on fruits at 230 days after anthesis resulted in uniform ripening of fruit on greenhouse grown coffee plants. The mechanism of abscission of green and ripe fruits was studied. No abscission layer was found at the sites of detachment in either green or ripe fruits. The detachment of ripe fruits occurred at random, by the breaking of parenchymatous pericarp tissue immediately above the pedicel. In contrast, the detachment of green fruits occurred at random along the pedicel. The FRF of green fruits was greater than the FRF of ripe fruits. The FRF decreased as fruits matured in both the ethephon and control treatments. Indices of fruit maturation were correlated with FRF. Exocarp color change, expressed quantitatively as the degree of lightness (L) and hue angle (0), was correlated with the FRF. The soluble solids content of the pericarp tissue decreased as fruit matured. There was a strong inverse correlation between FRF and soluble solids content of the pericarp. Further reduction in the FRF of ripe fruits was achieved by mist irrigation. The FRF of green fruits was not affected by the mist irrigation treatment. These studies provide strong evidence for the selective harvesting of mature coffee fruits by machine by integration of synchronized flowering and fruiting, and the reduction in FRF of ripe fruits.
Papaya Fruit Softening: Role of Hydrolases
(University of Hawaii at Manoa, 2007) Thumdee, Siwaporn
Hydrolases have been detected during fruit softening and may play an important role in papaya softening. Variation in softening of papaya varieties and the incomplete softening of papaya treated with 1-methylcyclopropene (1-MCP) present an opportunity to determine the factors causing fruit softening. To determine whether six hydrolases and pH are involved in papaya softening, comparison of cell wall modification, hydrolases’ activities, and mesocarp pH between papaya that differ in softening rates, and normal softening versus softening modified by 1-MCP were used. Mesocarp of ‘Line 8’ and ‘Sunset’ papayas showed significant losses in cell wall mass during normal softening, but papaya did not lose the mass when softening was restrained by 1-MCP treatment. Solubilizations and dissociations of pectic polysaccharides and loosely bound matrix polysaccharides that consisted of xylosyl and galactosyl residues at high concentration were noticeable during normal softening. Although the major changes in galactosyl components of cell wall in 1-MCP-treated papaya were comparable to those in control papaya, the 1-MCP-treated papaya did not soften completely. The comparison of cell wall modification between 1-MCP-treated papaya and control papaya confirmed that the modification of xylosyl component of cell wall was involved in the abnormal papaya softening when treated with 1-MCP. Activities of p-galactosidase, endoglucanase, endoxylanase, and B-xylosidase were correlated with fruit softening. When softening was modified by 1-MCP treatment, a rise in activity of these hydrolases was delayed; but only endoxylanase activity was completely suppressed throughout ripening. During softening, a change in mesocarp pH was implicated. Mesocarp pH of ‘Line 8’ and ‘Sunset’ papayas declined when fruit started to soften with no reduction in 1-MCP-treated papaya. Applied low pH affected mesocarp firmness, but the effect varied with the stage of fruit ripeness and specific fruit tissue. Papaya softening is a complex event that involves many cell wall hydrolases, such as endoxylanase, (B-xylosidase, B-galactosidase, and endoglucanase. These hydrolases may play their roles in concert, to provide the unique texture of a particular fruit. Endoxylanase appears to play a major role in papaya softening. A regulated decline in mesocarp pH during ripening may regulate these hydrolases and impact papaya mesocarp softening.
Flower Pigments in Yellow Dendrobium Species and Hybrids
(University of Hawaii at Manoa, 1984) Kanchit Thammasiri
Carotenoids and chlorophylls in yellow petals of Dendrobium species and hybrids were ex amine d by high-performance liquid chromatography (HPLC). Six carotenoids, neoxanthin, violaxanthin, antheraxanthin, lutein, zeaxanthin, and B-carotene, and chlorophyll a and b were identified. Lutein, zeaxanthln, and B-carotene were the major pigments responsible for yellow flower color in several dendrobiums. Color was affected by the numbers and concentrations of pigments. The degradation of flavonoids, carotenoids, and chlorophylls in the flowers at different stages of maturity within a raceme was examined for three progenies, K528 (pale yellow), K637 (white-purple), and K650 (bright yellow). The amounts of carotenoids and chlorophylls in crosses K528 and K637 decreased rapidly after blooming, while cross K650 maintained a high carotenoid content in all stages of maturity. Flavonol content in all three crosses did not show any change over time. Carotenoid and chlorophyll changes in growth and development from the bud stage to flower maturity were determined qualitatively and quantitatively in crosses K528 and K637. All 6 carotenoids and 2 chlorophylls in both crosses declined continually from the bud stage to 2-4 weeks after blooming. The inheritance of yellow flower color in Dendrobium appears to be complex, since at least 6 carotenoids and chlorophyll a and b have been shown to co-exist. Degradation of yellow pigments is not uncommon, and polyploidy further complicates the analysis of color inheritance. Since both carotenoid and chlorophyll concentrations in hybrids often fall between those of the parents, it appears that yellow color is mostly quantitatively inherited although interactions with modifying genes can be significant.
Bud Sprouting and Growth of Cyperus Rotundus L. Altered by Cytokinins
(University of Hawaii at Manoa, 1973) Teo, Christopher Kheng Hoe
Varying concentrations of N-6-benzyl adenine (BA), indoleacetic acid (lAA), gibberellic acid (GA), abscisic acid (ABA), and 2-chloroethylphosphonic acid (ethephon) were used to induce sprouting of dormant nutsedge (Cyperus rotundus L.) tubers, BA at 50 to 300 ppm stimulated sprouting. The continuous presence of BA during the sprouting period was necessary to give significant sprout stimulation. Kinetin and 6-benzylamino-9-(tetrahydropyran- 2-yl) 9H-purine (PBA) showed similar stimulatory effects on sprouting. Neither lAA at 1, 10, or 100 ppm; GA at 10, 100, or 1000 ppm; nor ethephon at 10, 100, or 1000 ppm had stimulatory effects on sprouting. ABA reversed the stimulatory effects of BA when tubers were treated with ABA following BA treatment. Sprouting was markedly greater at 33 0 day, 25 C night than at 2k C day, 1? C night. There was no difference between cytokinin-induced sprouting in single tubers and that of tubers in intact rhizome chains. Enhanced sprouting was the same in light or darkness. Soilapplied cytokinin resulted in sprout stimulation similar to that observed in petri dishes and in sand culture. Growth of plants originating from tubers pretreated with 100 ppm BA did not differ significantly from the controls. Sustained foliar applications of BA at 100 and 200 ppm produced numerous plants with tuft-type growth habit, delayed flowering, and reduced the number of inflorescences. Numerous short, diageotropic rhizomes were produced. The acidic ether extract from purple nutsedge tubers showed the presence of inhibitory substances in the acidic ether fraction. These inhibitors were generally referred to as inhibitory. Inhibitor y6* inhibited sprouting of excised purple nutsedge buds as well as elongation of wheat coleoptile. The inhibition of bud sprouting by inhibitory was relieved by BA. Application of ABA also inhibited sprouting of the excised buds and this was similarly reversed by BA applications. Inhibitor^ mainly consisted of phenols and possibly ABA as a minor component. The suggested role of BA in enhancing sprouting of purple nutsedge tubers was to antagonize inhibitor actions. The feasibility of the use of cytokinin-like substance to precondition purple nutsedge for subsequent eradication was discussed.
Anthocyanin Expression and Phenyalanine Ammonia-Lyase Activity in Sorghum Bicolor as Influenced by Temperature and Plant Age
(University of Hawaii at Manoa, 1976) Tanabe, Michael J.
The effects of temperature and plant age on anthocyanin production and Phenylalanine ammonia-lyase (PAL) activity in etiolated Sorghum bicolor seedlings were investigated in this study. The etiolated seedlings were exposed to various temperature combinations and sucrose in the presence and absence of light. After these treatments, they were analyzed for anthocyanin content or PAL activity. Anthocyanin formation was not affected by temperature or sucrose in the absence of light. This indicated that light was required for the activation and/or synthesis of anthocyanin synthesizing enzymes. This was not the case for PAL which was stimulated in darkness when sucrose was added to the medium. It was speculated that the exogenous source of carbohydrates served as a substitute stimulus for light. Anthocyanin formation was stimulated by temperature in the presence of and following exposure to light. Limited quantities of anthocyanin were produced at 30C 4 hours after seedling exposure to light. The effect was of a much greater magnitude 24 hours after exposure to light. The additional time period required for maximal anthocyanin production was attributed to the presence of a lag phase. It was further assumed that temperature affected the production and/or activity of anthocyanin synthesizing enzymes during this lag phase; a higher temperature being more effective than a lower temperature. Endogenous carbohydrate supply was also considered to be important. Anthocyanin production was high only when the seedlings had been exposed to low (IOC) temperatures prior to light exposure. The low temperature was thought to decrease respiration rates of the seedlings and therefore make more substrates (e.g. endogenous carbohydrates) available for anthocyanin formation during and following exposure to light. PAL activity was greatly stimulated by a temperature of 30C 4 hours after the initiation of the light treatment but its activity decreased markedly 24 hours following exposure to light. It was assumed that light and high temperatures functioned as stimuli for the synthesis and/or activity of a PAL deactivating enzyme system. The effectiveness of this system to deactivate PAL was thought to be greatly increased during a 24 hour incubation period after exposure to light. This was the case only when the temperature was high (30C), therefore it was assumed that the activity and/or synthesis of the PAL deactivating enzyme system was hampered by low (IOC) temperatures. Sucrose had a greater stimulatory effect on PAL activity at the lower temperatures. This might have been a result of the absence or low activity of a PAL deactivating enzyme system at low temperatures and/or the greater availability of endogenous substrates due to lower respiration rates. As plant age increased, anthocyanin production and PAL activity decreased. It was postulated that this was a result of lower endogenous substrate levels due to longer respiration times. The older plants also may have produced greater quantities of anthocyanin and PAL inhibitors. Maximal PAL activity was found to precede maximal anthocyanin production by a few hours. The trend was similar for minimal PAL activity and anthocyanin production. A lag phase was speculated as being responsible for this relationship. If this assumption is correct, our studies indicate that PAL activity might have some regulatory control over anthocyanin production.
Inheritance of Resistance to Watermelon Mosaic Virus 2 in Cucumber (Cucumbis Sativus L.)
(University of Hawaii at Manoa, 1974) Takeda, Kenneth Yoshi
Characterization of Sprouting of Cyperus rotundus L. Tubers under Fluctuating Temperatures
(University of Hawaii at Manoa, 1996) Sun, Wen-Hao
Effects of fluctuating temperature on budbreak and shoot elongation, and the role of Ca2+ in bud break via heat pulse were determined in purple nutsedge {Cyperus rotundus L.) tubers Dormant tubers were transferred to 35C for 30 minutes from 20C and 80% to 92% budbreak occurred. Tubers at 20C without the heat treatment had 20% to 25% budbreak. Even a 3-minute 35C pulse caused 62% budbreak. Budbreak following 35C for 12 hours was 92%, similar to that obtained with seven cycles of 20/35C (12/12 hours). A change in temperature from 25 to 15C or from 20 to 25C did not promote budbreak compared with constant 25 or 20C respectively. Varying the rate of temperature increase from 0.02 to 0.5C per minute in a single temperature shift from 2 0 to 35C had no effect on budbreak. Tuber sprouts exposed to alternating temperatures with 12-hour 30C and 12-hour 40C elongated to 37 mm, 1.3 times higher than at constant 35C, an optimal mean temperature. Temperature differences of 2 and 4C in alternating cycle around the mean 24C had little effect on growth; an 8 C differential had 21 mm greater shoot length than at constant 24C. A single warm pulse of 35C for 1 h caused 60% to 70% budbreak of excised buds, and was substituted by ionomycin, and reduced by EGTA and verapamil. Excised buds without the single 35C pulse or with 1 mM verapamil had 36% to 42% budbreak. Suspension-cultured cells from purple nutsedge shoot tip loaded with fluo-3 AM resulted in cell expansion within 10 minutes. Intracellular [Ca2+J decreased or increased initially, then steadily increased with a 35C treatment, accompanied by the appearance of cytoplasmic strands. Withdrawal of heat stimulus did not cause a reduction of intracellular [Ca2+] in 30 minutes. In conclusion, a single warm pulse stimulated budbreak of purple nutsedge, but not shoot elongation; the shoot elongation response was thermoperiodic. Ca2+ may mediate the heat pulse-stimulated budbreak. The heat pulse also elevated the intracellular [Ca2+] of cultured cells.
Genetic Improvement of Leucaena and Acacia Koa
(University of Hawaii at Manoa, 1996) Sun, Weiguo
Studies on Leucaena and Acacia koa tree improvement were undertaken in Hawaii from 1992-1996. These studies were described in two sections. The first section includes identification of high biomass yield varieties, estimation of DNA content, vegetative propagation, and forage yield management among Leucaena species and hybrids. Among interspecific hybrids of KX2 F1 (L. pallida x L. leucocephala) and 3-way crosses (A. pallida x KX3 F1 (L. diversifolia x L. leucocephala)), the best entries yielded over 16 Mg ha-1yr-1 of edible forage dry matter and over 40 Mg ha-1yr-1 for wood biomass. All these hybrids were psyllid-tolerant. Heterosis for forage yield averaged 48% (-75 to 160%) and for wood biomass averaged 85% (-99 to 223%). Among intraspecific hybrids involving six L. leucocephala accessions, the best entries were the crosses between K397, K565, and K608. They outyielded a widely planted K636 (L. leucocephala). Heterosis for biomass yield averaged 16% (-28% to 80%). A composite from the selected intraspecific hybrids was released. Nuclear DNA content varied from 1.32 to 1.74 pg/2C for diploid species and from 2.67 to 3.09 pg/2C for tetraploid species. Successful cloning method with more than 80% rooting for KIOOO and KlOOl was developed. More than 30% increase in forage yield was obtained by optimizing the harvest intervals of K636 and KX2 F1. The second section includes studies of the identification of quality seed source for reforestation and selection of superior progenies for genetic improvement among Acacia koa collections. A total of 334 koa accessions were collected from the Hawaiian Islands. These accessions were evaluated for various important traits from seed to tree growth characters. Seven field trials involving 178 accessions were established at Hamakua, Hawaii and Mauanawili, Oahu. The koa populations clearly showed great variations in these traits. These variations are essentially genetic in origin and are useful in selecting progenies for tree improvement. High quality koa seed sources from the Islands were identified. The advanced progenies based on fast growth and tree form were selected for further testing. Silviculture practice study showed that koa trees in the mixed plots grew significantly slower than trees grown alone.

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