Receptacle and Ovary Assimilate Concentrations and Subsequent Boll Retention in Cotton
- James J. Heitholt and
- John H. Schmidt
Assimilate supply or flux to developing cotton (Gossypium hirsutum L.) bolls (fruits) may help determine whether those bolls are retained or abscised. Most bolls that abscise tend to do so within a few days post anthesis (DPA), and little is known about the relationship between assimilate levels in young fruiting forms and their relationship to boll retention. Therefore, the objective of this study was to determine the relationships of young receptacle and ovary assimilate levels to boll retention among genotypes and sympodial branch positions. Eight genotypes of cotton (four cultivars and four leaf-type isolines) were grown in the field in 1989 and 1990 using conventional cultural practices. Boll retention percentages (bolls/tagged flowers) and assimilate concentrations of excised receptacles and ovaries at Fruiting Positions 1, 2, and 3 were determined at 5 d preanthesis, 0 DPA, and 2 DPA. Position 1 boll retention (54 to 75%) was greater than that of Position 2 (19 to 45%) but the concentrations of soluble sugars in their excised receptacles and ovaries were similar. Variation in retention among genotypes at Position 1 was either small or nonsignificant but was significant at Position 2. Boll retention, glucose, and starch concentration of Position 2 MD 65-11 super okra-leaf bolls were lower and N concentration higher than the other genotypes. However, assimilate levels did not appear to explain the variation in retention among the eight genotypes. Other factors, such as C metabolism in ovules, may need to be examined in order to explain the physiological reasons for differences in boll retention.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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