M.S. - Agronomy and Soil Science

Permanent URI for this collectionhttps://hdl.handle.net/10125/585

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Species-specific plant-soil interactions in a Micronesian mangrove forest
(University of Hawaii at Manoa, 2000) Gleason, Sean Michael; Agronomy & Soil Science
Mangrove forests often exhibit strong patterns of species distribution along salinity and elevation gradients. Previous efforts to explain this phenomenon have correlated species occurrence with various hydrologic, soil, and porewater variables. Because s
Effects of Exchangeable Soil Calcium, Magnesium and Calcium/Magnesium Ratios on Plant Nutrition and Growth of Lettuce on an Ultisol
(University of Hawaii at Manoa, 1999) Zhang, Guo Qing
Two greenhouse pot experiments were conducted to study the effects of exchangeable soil calcium, magnesium and calcium/magnesium ratios on nutrition and growth of lettuce (Lactuca sativa L.) on an Ultisol (Manana soil series) with low pH (4.35), Ca (0.57 cmolc kg-1) and Mg (0.60 cmoh kg-1) in Hawaii to obtain calibration data for Ca and Mg in Hawaii soils and test the current sufficiency recommendations for Ca and Mg for making fertilizer recommendations. The objectives of this study were; to identify the sufficiency levels of exchangeable soil Ca and Mg for growth of lettuce; to investigate the validity of an ideal Ca/Mg ratio for growth of lettuce and to determine the effects of soil Ca and Mg levels as well as Ca/Mg ratios on soil nutrients and the nutrition and growth of lettuce. Lettuce yield increased as soil Ca increased and also as plant Ca level increased. The Cate- Nelson method was applied to determine the critical levels of Ca, Mg and the Ca/Mg ratio in the soil and plant. A critical soil Ca level for lettuce was determined to be 1.9 cmolc kg-1 and is more reasonable and lower than the value of 5 cmok kg-1 that is currently recommended in Hawaii. Lettuce in the zero Ca treatment with 0.57 cmoh kg-1 soil Ca exhibited Ca deficiency symptoms in the Ca experiment. A critical plant Ca concentration for lettuce at maturity was also determined to be 4 g kg-1. Exchangeable soil cations interact with each other and application of a large amount of liming material can cause cation imbalance. In the Ca experiment, soil Mg, K and Na decreased as soil Ca increased. Application of Ca increased the soil Ca level, increased Ca uptake by the plant and reduced the uptake of Mg and Na but had no effect on the uptake of P. Soil Ca restricted K uptake at low Ca levels due to decreased ion selectivity and leakiness of membranes membranes when Ca was deficient. Lettuce growth was normal with all soil Mg levels in the Mg experiment. Lettuce yield also was not related to plant Mg level. A critical soil Mg level for lettuce could not be established, however, the soil Mg level of the zero Mg treatment, 0.67 cmoU kg’\ was apparently adequate for normal lettuce growth. Therefore, the sufficiency range for soil Mg recommended in Hawaii (2.5 to 3.3 cmok kg'^) appears too high. Lettuce in the zero Mg treatment did not show any Mg deficiency symptoms. A critical plant Mg concentration for lettuce at maturity also could not be determined, however, the plant Mg concentration of the zero Mg treatment, 4 g k g '\ was apparently sufficient for normal growth of lettuce. Interactions between soil cations also occurred in the Mg experiment where soil Ca, K, and Na decreased as soil Mg increased. Increased levels of soil Mg increased the uptake of Mg by the plant, and reduced the uptake of Ca and Na, but had no effect on the uptake of K and P. In the soil Ca/Mg ratios ranged from 0.11 to 7.70, lettuce growth was limited by a Ca/Mg ratio of around 0.11 and no yield reduction was observed in the Ca/Mg ratio range from 0.50 to 7.70, which is within the optimal range. This study provides evidence for the conclusion that plants can grow normally within a broad range of Ca/Mg ratios. Lettuce yield was related to both soil Ca/Mg ratio and plant Ca/Mg ratio. The lower critical level of the soil Ca/Mg ratio for lettuce was determined to be 0.5. However, caution should be used in interpreting yield response to the soil Ca/Mg ratio because soil Ca or Mg levels can also affect plant growth. The critical plant Ca/Mg concentration ratio for lettuce at maturity was also determined to be 0.5. Plant Ca/Mg ratios in lettuce were significantly related to soil Ca/Mg ratios.
Seed Quality of lsogenic Endosperm Mutants in Maize
(University of Hawaii at Manoa, 1995) Zan, Guo-Hua
Five studies were conducted based on ten near-isogenic corn hybrids converted to four endosperm genotypes — +, su, bt and sh2. Five different types of germination tests were conducted, including accelerated aging. Among the four endosperm genotypes, seed with wild type endosperm always had the best viability, followed in turn by su, bt and sh2 hybrids. Electrolyte leakage caused by accelerated aging (AA) was highly correlated with the deterioration of viability caused by AA. Seeds with poor germination ability suffered more from AA, indicating that seeds with good germination ability will have better storability. The accelerated aging, therefore, should be useful for predicting viability loss in seed storage. Pericarp thickness was influenced greatly by endosperm mutant genes. Pericarp thickness of sh2 hybrids at 36 days after pollination (DAP) were significantly greater than those at 18 DAP, while thinning trend of pericarp thickness was observed for wild type hybrids. There was no significant difference for bt and su hybrids from 18 to 36 DAP. A highly significant correlation was observed between seed weight and the difference of pericarp thickness harvested at 18 and 36 DAP. The data were interpreted as evidence for the effects of inner (endosperm) pressure on pericarp distension. The comparisons of eating quality among su, bt and sh2 endosperm mutants showed in general, that su had the worst and sh2 had the best eating quality considering sweetness and flavor, although the difference between bt and sh2 was not significant for many hybrids. The extensive genotypic variability for these eating qualities among the bt hybrids suggests that the allelic variation at loci other than bt is probably involved. Six germination-related characters were evaluated for bt and sh2 hybrids. These were seed weight, pericarp thickness, bubble volume, seed density, leachate conductivity and sweetness. In general, sh2 seed was sweeter with lower seed weight and density, and higher pericarp thickness, leachate conductivity and bubble volume (between endosperm and pericarp in mature seeds). These differences could be largely attributed to the efficiency of bt and sh2 genes in hindering the conversion of sucrose to starch. A method of measuring bubble volume through the change of soapy water volume was developed. The hypotheses were proved that bubble volume was determined by both shrinkage of endosperm and pericarp thickness, and thick pericarp affects germination rates of super sweet corn adversely through its effect on the formation of a large bubble volume. Bubble volume was observed to cause severe imbibition damage even with intact pericarps. The correlation between seed weight and germination was positive and significant at 5% level. The correlations of germination with pericarp thickness, bubble volume, seed density and conductivity were highly significant, as were the correlations among these four characters. However, germination was not significantly corrected with sweetness (organoleptic).
Nitrogen Fertilization and Nitrate Accumulation in Some Hawaiian Plants and Soils
(University of Hawaii at Manoa, 1975) Yusop, Mohamad Khanif
Effects of Physico-Chemical Properties on the Bulk Electrical Conductivity of Tropical Soils
(University of Hawaii at Manoa, 1981) Yu, Wang Ki
Effects of Thermoperiod on the Stomatal Opening and Transpiration of Pineapple (Ananas comosus (L.) Merr.)
(University of Hawaii at Manoa, 1969) Yoder, Ronald Carroll
Studies in the Inheritance and Enzymatic Detection of Ratoon Stunting Disease of Sugarcane
(University of Hawaii at Manoa, 1968) Yassin, Mohamed Awadalla
The Phosphorus Nutrition of Seedlings in Relation to Phosphate Fixation By Two Hawaiian Soils
(University of Hawaii at Manoa, 1963) Yaptenco Jr. Catalino Camanzo
Residual Effects of Herbicides in Soils and Methods For Their Evaluation
(University of Hawaii at Manoa, 1965) Yang, Cecilia Han
Adsorption of S-Triazine Herbicides on Soils as Affected by Adsorbent-pH Interactions
(University of Hawaii at Manoa, 1968) Yamane, Vernon Keiso
Comparative Studies of Oxic Horizons
(University of Hawaii at Manoa, 1969) Yaibuathes, Nuanchavee
A Model of the Microclimate in Porous Shade Houses
(University of Hawaii at Manoa, 1994) Xia, Haifeng
The first shade-house microclimatic model was developed based on the energy and moisture balances of four shade-house system components - the shade cloth, inside air, canopy, and soil surface. The transport is parameterized by resistances for small-scale turbulence and by intermittent refreshment for large-scale non-local gusts. The temperature and humidity in a semi-infinite shade house are predicted when the six coupled differential equations based on the energy and moisture balances are simultaneously solved. The model includes liquid-water balances for surfaces. The model requires only weather data, and, if desired, measured shade-house characterization data. Weather data for running the model, inside temperature and humidity data for verifying the model, and energy balance and turbulence data for further development of the model processes were collected in a large commercial shade house near Pahoa, Hawaii from 10 January to 25 March 1992.
Root Tuberization and Nitrogen Fixation by Pachyrhizus erosus (L.)
(University of Hawaii at Manoa, 1979) Woomer, Paul Lester
Population Dynamics of Rhizobium japonicum and Rhizobium leguminosarum in Host and Non-Host Rhizospheres
(University of Hawaii at Manoa, 1982) Woolfenden Ii, Robert Baines
The Suitability of Some Typic Paleudults for Oil Palm Production
(University of Hawaii at Manoa, 1978) Wiles, Walter T.
The Effects if Several Herbicides on Eight Sugarcane Varieties
(University of Hawaii at Manoa, 1963) Wiemer, Robert Dale
Since the introduction of 2,4-D compounds in 1945, many new herbicides have been tested in the Hawaiian sugar industry and several have been accepted for commercial use. Much has been learned about the weed control activity of the different herbicides, but little has been learned about their effect on sugarcane varieties. If more were known about the variation in response of sugarcane varieties to herbicides, better use might be made of several of the herbicides without inducing cane damage. Rates of herbicide application could be determined for tolerant or susceptible varieties, if other factors were equal, and recommendations could be made as to the safety of pre-emergence or post-emergence applications, singly, or in combination, for sugarcane varieties. To determine whether or not varietal differences occur in response of sugarcane to herbicides, a three-factor experiment was installed using eight commercial sugarcane varieties and eight herbicides applied by four methods at one level of application. The herbicides used were monuron, diuron, linuron, atrazine, proraetone, dalapon, amitrole, and 2,4-D. The methods were: (A) herbicide applied over exposed seed pieces; (B) herbicide applied over covered seed; (C) herbicide applied over cane 20-30 inches tall; and (X) check, no herbicide applied. Germination counts were made and analyzed. At approximately seven months of age all plots were harvested and the cane weighed. These weights were then subjected to analysis of variance. Weed control and cane effect ratings were made periodically. Results indicated the variety factor to be the most important in both germination counts and harvest weights. Varieties which were inherently poor in germination and growth were most susceptible to herbicide damage. Three varieties exhibited high tolerance of herbicides as measured by germination counts, four were intermediate, and one was susceptible to damage. Six varieties exhibited relatively high tolerance of herbicides as measured by harvest weights. Two varieties were quite susceptible to herbicide damage. Herbicides applied over exposed seed pieces (method A) tended to reduce germination. Post-emergence application over cane (method C) tended to decrease harvest weights. Normal pre-emergence (method B) was the least damaging treatment. The most effective herbicides tested for pre-emergence weed control were atrazine and prometone, followed by monurori, diuron, and 2,4-D. Diuron and linuron were the most effective post-emergence weed control herbicides tested. Observational gradings on cane effect agreed in general with those obtained for the analysis of harvest weights.
Effect of Nitrogen and Season on the Yield, Protein, and Amino Acid Contents of Two Hawaiian Corn Varieties
(University of Hawaii at Manoa, 1976) Watanabe, Winifred Naomi
The Identification and Inheritance of the Yellow Flower Pigments in Desmodium Sandwicense E. Mey.
(University of Hawaii at Manoa, 1969) Walker, Phyllis Ann
The purpose of this thesis was to study the chemistry and genetics of flower pigments in D. sandwicense E. Mey. Eleven parental lines, exhibiting flower color variation from near-white to light and dark purple, were selected for this study. Crosses were attempted among the lines, using white-flowered plants as the female parents. Due to difficulties encountered in the crossing, attributable to technique and/or environmental conditions, and/or inherent in the species, no true crosses were obtained. Consequently, the inheritance studies proposed were abandoned. Pigment identification using paper chromatography involved two steps: 1) analysis of the aglycones present and 2) analysis of the glycosides present. Aglycone extracts were obtained using hydrolysis of the petal tissue, and glycosides were obtained by extraction with methanol or methanol-HCl. BAW was the primary solvent system used; other systems were HAc-HCl, 1%HCl, 15%HAc, 60%HAc, 60%IP, (IPnisopropyl alcohol), Forestal, and TAW. The components of these solvent systems are readily available in the literature. Identifications were based upon Rf-values for the various solvent systems and upon color reactions in visible and ultraviolet light, both with and without ammonia vapor. Sufficient quantities of concentrated extract were difficult to obtain, thereby hindering conclusive identification of the compounds present. It was indicated that the phenolic composition of the petals was much more complex than previously reported. An earlier study demonstrated the presence of an anthocyanidin, malvidin, as well as glucose, and a single anthocyanin, malvidin 3, 5-diglucoside. In addition, the presence of eight yellow pigments and three colorless compounds, which fluoresced in ultraviolet light, was demonstrated (42, 44). In the present study, a considerably larger number of components than the above was indicated. Tentative identification of the aglycones and glycosides is presented below. Aglycones: malvidin, kaempferol, quercetin, ferulic acid, ellagic acid. Less conclusive evidence suggested: gossypetin, mimuletin, patuletin, isorhamnatin, p-coumaric acid, sinapic acid. Glycosides: malvidin 3, 5-diglugoside. At least two glycosides of flavones and/or flavonols; one may have been kaempferol 3-glucoside. Interrelationships among the pigments in the production of phenotypic color variation in the species may be summarized as follows: Delphinidin*: blue, mauve Malvidin (methylation): reddening Malvidin 3, 5-diglucoside (3,5-diglycosylation): intensifying * Malvidin is a methylated derivative of delphinidin. Possible scylation*: dulling Co-pigmentation, due to presence of flavones. Flavonols: blueing Background effects, due to: 1) Presence of flavones, flavonols: cream or yellow background, if these pigments are present in high concentrations; etc.; 2) Chalcones, aurones(?): orange or yellow background; and/or 3) Carotenoids(?): background effect of plastid-borne pigments Flavonols and flavones: give “body” to white petals; may contribute to whiteness Chalcones and aurones (?): orange- or yellowing Carotenoids (?) + anthocyanins: result in purple or magenta colors pH effects (?), due to: 1) Low pH: reddening; or 2) High pH: blueing; colorless pseudo-base. The interaction of these effects results in very complicated interrelationships in the production of phenotypic flower color in D. sandwicense. The conclusive identification of all pigments and phenolic compounds present, and the determination of their distribution and concentration among color classes, would have to precede elucidation of the above interactions. * The possibility of acylation was suggested by the tentative identification of cinnamic acids.
The Changes in the Distribution of Pasture and Weed Species in a Grazed Tropical Pasture
(University of Hawaii at Manoa, 1979) Wahab, Hassan Bin Abdul
This pasture ecological study was conducted at Hawaii Agricultural Experiment Station, Kauai Branch, from July 1978 to October 1978. The pasture area covered two steep-sided slopes facing north and south. A valley which rims east and west separates the two slopes. No fertilizer was added to the pasture since 1970 and the area was continuously grazed since 1973. The objective was to find the changes in species distribution and soil factors comparing results of the same area studied in 1971 (Nicholls, 1972). Data were collected using the belt transect method. Of the dominant pasture species of 1971, intortum [Pesmodium intorturn (Mill.) Urb.] had disappeared from the pasture, green panicgrass [Panicum maximum Jacq. (var. trichoglume Eyles)] was only found on middle sections of both slopes in areas where it was protected from grazing. Stylo [Stylosanthes gaianensis (Aubl.)] and pangolagrass [Pigitaria dec^umbens Stent.] had spread to lower parts of the slope. In 1978, the pasture was dominated by weeds. The species present in greater frequency at all locations in the pasture were Hawaiian elephantfoot [Elenhantopus mollis H. 3. K.], Boston fern [Nephrolenis exaltata (P.) Schott.], glenwood grass [Sacciolepis indica (Wight & Arn.) Hitchc.] and sour paspalum [Pasnalum con.jugatum Bergius ] . Hawaiian elephantfoot had spread to the valley bottom. Indicator weed species of pasture deterioration such as lantana [Lantana camara L.], melastoma [Melastoma malabatricum L.], nettleleaf vervain [Stachytarpheta urticaefolia (Salisb.) Sims] had increased in numbers, while American burnweed [Erechtites hieracifolia (L.) Raf.] decreased in number. Other weed species present in 1978 were knotroot foxtail [Setaria geniculata (Lam.) Beauv.] and ricegrass paspalum [Pasnalum orbiculare Forst.] dominating the middle and top sections of the slope, and guava [Psidium guajava L.] dominating the valley bottom. Soil factors were also measured. Soil extractable P decreased while exchangeable K, Mg and Ca increased since 1971. The deteriorating pasture of 1978 produced very low dry matter production for cattle feed.
The Characteristics and Genesis of the Akaka and Hilo Soils of the Island of Hawaii
(University of Hawaii at Manoa, 1969) Voss, Roylyn Lee

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