Differential Recovery Among Cotton Genotypes Following Early-Season Defoliation1
- C. Wayne Smith and
- J. J. Varvil2
An objective of many cotton (Gossypium hirsutum L.) breeding programs is the development of faster fruiting or earlier maturing cultivars. Such cultivars may allow producers to avoid production problems associated with early planting or late harvest as well as aid in disrupting the parallel buildup of certain pests with increased fruit load. Three cotton genotypes exhibiting different genetic maturities were evaluated over a 3-year period to determine degree and speed of recovery from earlyseason defoliation, simulating stress due to hail damage. Arkugo 4, a fast-fruiting strain; ‘DES 56’, a moderately early-maturing, mid-South cultivar; and ‘Deltapine 61’ (DPL 61), a full-season, mid-South cultivar were defoliated immediately above the first true-leaf node when at the V5 and R2 stages of growth. A nondefoliated control of each genotype was included. When compared as a percent of nondefoliated controls (to remove the confounding effects of yield potential), the faster fruiting Arkugo 4 was not significantly lower yielding than its control when defoliated at the V5 stage in 1980 and 1981. Defoliation of DES 56 and DPL 61 at stage V5 caused a significant decrease in yield each year. Defoliation of all genotypes in all years at the R2 stage, except for Arkugo 4 in 1982, reduced or further reduced yield below that of defoliation at the V5 stage. Arkugo 4 also recovered more rapidly than DES 56 or DPL 61 following defoliation at both growth stages in 1980 and 1981, but not in 1982. These data indicate that yield-competitive, fast-fruiting cultivars have the potential to recover from early-season stress more rapidly and to a greater degree than moderately early-season or full-season, mid-South cultivars.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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