Supplemental Boron, Boll Retention Percentage, Ovary Carbohydrates, and Lint Yield in Modern Cotton Genotypes

Abstract

Cotton (Gossypium hirsutum L.) is sometimes grown on soils with low B concentration. However, most of the literature regarding the effects of supplemental B on cotton was obtained from obsolete, low‐yielding genotypes rather than modern, high‐yielding genotypes. Therefore, the objective of this study was to determine the effects of soil‐ and foliarapplied B on leaf blade B concentration, boll retention, and lint yield of modern cotton genotypes. In 1991, three genotypes (DES 119, DES 24‐8 ne normal leaf, and DES 24‐8 ne okra leaf) and in 1992, two genotypes (Deltapine 20 and Deltapine 5415) of cotton were grown in the field on a Beulah fine sandy loam (coarse‐loamy, mixed, thermic Typic Dystrochrepts) having 0.11 mg kg−1 hot water extractable B concentration. Treatments included preplant soil and foliar (first flower to end of bloom) B (78% Na2B8O13·4H2O, 20% Na2B4O7·5H2O) applications for seasonal totals of 0, 0.89, or 1.78 (1992 only) kg B ha−1. The lowest rate of foliar‐applied B increased leaf blade B concentration from 25 to 70 mg kg−1 in 1991 and from 54 to 108 mg kg−1 in 1992. In 1992, the highest rate of foliar B applications resulted in a leaf blade concentration of 154 mg B kg−1. Soil‐applied B did not alter leaf blade B concentration in 1991, but slightly increased leaf blade B concentration in 1992 from 54 to 71 mg kg−1. Soil B concentrations were higher during the midseason than the preplant period, suggesting that preplant soil B analysis may not accurately foreshadow soil B supply during the season. Soil B or foliar B applications did not affect boll retention percentage, flower number, or lint yield in either year. Supplemental B did not affect boll distribution in 1991, but in 1992, foliar B applications increased the percentage of fruit on monopodial branches. In both years, supplemental B did not greatly affect fiber properties with the exception that supplemental B increased fiber micronaire reading of Deltapine 20 in 1992. The results suggest that modern cultivars may not always need supplemental B when soil B concentration is moderately low.

Boron Requirement of Irrigated Cotton in a Typic Haplocambid for Optimum Productivity and Seed Composition

“…Fiber length of B-deficient plants was 28.5 mm, which was enhanced up to 29.1 mm with B use. These results are in agreement with those of Hearn (1981), Heitholt (1994), Makhdum et al (2002), and Zhao and Oosterhuis (2002), who also reported that B fertilizer did not affect cotton fiber quality. They also opined that fiber quality is controlled by genetic and environmental factors rather than plant nutrition.…”

“…Soomro et al (2000) reported an increase of 8.7% in boll weight with 2.0 kg B ha −1 in a calcareous soil having dilute HCl-extractable 0.39 mg B kg −1 . In contrast, Heitholt (1994) did not observe any positive effect of B fertilizer on seed cotton yield in an alkaline (pH 7.1-7.5) B-deficient (hot water-extractable 0.8 mg B kg −1 ) Typic Dystrochrept.…”

“…In irrigated Aridisols of Pakistan as well, B use enhanced seed cotton productivity (P < 0.05; Rashid and Rafique 2002). However, Anderson and Ohki (1972), Oosterhuis and Venter (1976), and Heitholt (1994) did not observe a positive impact of B use on cotton productivity.…”

Foliar boron application affects lint and seed yield and improves seed quality of cotton grown on calcareous soils

“…Moreover, the data from this study agrees with previous reports where they found an increase in cotton yields due to B applications (Howard et al 1998(Howard et al , 2000. However, there are several other reports where there was no effect of B application on cotton yield (Anderson and Ohki 1972;Heitholt 1994). This discrepancy may be because the experiments were conducted under different environments or using different cultivars that might respond differently under low-B environments.…”

“…This is probably because it is difficult to establish a critical available soil B concentration which will be universal over different environments and different soil types (Heitholt 1994;Goldberg 1997). Available soil B depends on soil organic matter, pH, temperature, N fertility, soil water status and soil texture which all affect availability and also uptake of B by plants (Goldberg 1997;Hu and Brown 1997).…”