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The Seasonal Fluctuation of Flower Production in Bird of Paradise as Affected by Leaf Cooling Practices in Hawai i

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Title:The Seasonal Fluctuation of Flower Production in Bird of Paradise as Affected by Leaf Cooling Practices in Hawai i
Authors:Kawabata, Osamu
Date Issued:1989
Abstract:Eighty 1-year-old seedlings of bird of paradise, derived from siblings of 4 seed pods, were planted in the field in Waimanalo, Hawaii in 1982. Three treatments were applied: misting, 4 seconds in 10- to 15-minute intervals in the daytime in August-November 1984 and again in June-October 1985; shading, 30% black polypropylene continuous shade starting in August 1984; and control. Leaf emergence, flower emergence, and flower harvest were recorded from June 1983 to June 1986. The effects of leaf cooling treatments on the occurrence of seasonal fluctuation in flower production and in flower abortion were investigated.
Using air temperature and solar radiation measured at 10-minute intervals, a response surface regression for control leaf temperature accounted for 79% of variation. Regression analyses in mixed mode further indicated that, while mean air temperature 5 mm away from leaves was 31.3°C in sunny summer afternoons, control leaf temperature rose to 33.3°C, and misting and shading significantly reduced it from control by 4.5 and 3.2°C, respectively.
Since characteristics in branch development and inflorescence bud development until leaf emergence were determined to remain unseasonal, flower production patterns were studied by simulating them from leaf emergence. Time intervals in inflorescence growth after leaf emergence were estimated by leaf degree-minute models observed at 10-minute intervals.
The models satisfactorily predicted monthly flower production pattern by correctly indicating the occurrence of 4 peaks in the May 1985-May 1986 within 1 month. The use of leaf temperature enabled an estimation that a peak flowering period in July-September 1985 was extended by 1 month to October with misting in summer.
Although as many as 45% of emerged leaves including 3.4% nonproducing leaves did not subtend flowers, flower abortion occurred all year without a seasonal fluctuation. Since leaf cooling by misting did not alter the number of flower abortion, flower abortion due to a high air temperature was judged unlikely to affect seasonal flower production pattern. Lack of available water and nutritional competition were suggested as possible causes of abortion.
Appears in Collections: Ph.D. - Horticulture

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