Early Season Development of Floral Buds in Cotton
- E. D. Ungar *,
- E. Kletter and
- A. Genizi
Improving irrigation and pest control strategies in upland cotton (Gossypium hirsutum L.) requires a better understanding of the factors influencing the formation and retention of fruiting bodies. The objective of this study was to investigate the effect of irrigation regime, boll load, and fruiting position upon floral bud dynamics. Field experiments were conducted during 3 yr on a Gan Shmuel vertisol (clayey, montmorillonitic, calcareous, thermic Typic Chromoxerert). Treatments comprised four irrigation patterns, and one zero-load (continuous flower removal) treatment. Dates of shedding, attainment of 1 cm size, and flowering were recorded by fruiting position for all buds on sympodia formed during the first 75 to 100 d after emergence. Of a total of 7972 buds observed, 51, 33 and 16% flowered, shed <1 cm size, and shed>l cm size, respectively. Shedding of buds <1 cm size was more sensitive to treatment than shedding of buds >1 cm size. The probability of bud formation at L2 and L3 was strongly affected by sympodium number (Ln represents the nth fruiting position on a sympodium). Flowering declined from 74% at L1 to 16% at L4. The zero-load treatment achieved the highest flowering percentage (66%) and number of fruiting positions per sympodium. The lowest flowering percentage (42%) resulted from severe, and relatively late, water stress. Strong positive associations between the shedding of contemporary buds at different relative positions on the plant indicate that an important component of shedding is the response to common stress stimuli. Weaker negative associations between the fate of noncontemporary buds can be explained by the negative feedback of boll load on bud retention.
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