Cotton (Gossypium hirsutum L.) requires boron (B), which plays a crucial role in the development of fruiting branches and bolls, in  the pollination, boll retention and fiber quality of this plant. However, B is mostly unavailable during flower development and pollination stages; therefore, it must be supplied in order to harvest higher yield and high-quality fiber. This study investigated the impact of different B doses (applied at various growth stages) on some of the fiber quality traits of cotton crop. Four B doses (i.e., 0, 1000, 2000 and 3000 ml ha-1) were applied at three growth stages (i.e., square initiation, flower initiation and peak flowering). The cotton genotype ‘Stoneville-468’, widely cultivated in the study region, was submitted to this experiment. Data relating to fiber uniformity, fiber strength, fiber fineness, fiber maturity, uniformity index, short fiber index, fiber elongation, reflectance, and yellowness were recorded. The results revealed that the application of 2000 ml ha-1 B at the square initiation stage resulted in the highest fiber length and uniformity. Similarly, higher B application during peak flowering resulted in the finest fiber. The increase in B application doses decreased fiber strength, negatively affected short fiber index, and had a non-significant effect on fiber maturity. The application of 1000 ml ha-1 B at flowering initiation resulted in the highest uniformity index. Similarly, the application of 2000 ml ha-1 B at flowering initiation resulted in the highest reflectance value. Likewise, the B application resulted in the lower yellowness values compared to the control treatment of the study. It is concluded that B should be applied to cotton grown on B-deficit soils. However, fiber quality traits are differently affected by B doses and application timing. Therefore, B application dose and timing should be decided according to the desired fiber traits. 

28.2.2023