Effects of sowing dates on lint yield, fiber quality, and use of nitrogen, phosphorus and potassium in cotton field-seeded after barley or oilseed rape harvest in Yangtze River Valley, China

This study aimed to evaluate the effects of sowing date on lint yield, quality, as well as nutrient uptake and use of cotton field-seeded after barley or oilseed rape harvest in the downstream Yangtze River Valley. Sowing dates were randomly assigned (15-May, 25-May, 4-June, 14-June, and 24-June), using short-season cotton (CCRI 50) in fields in Nanjing, Jiangsu Province of China, between 2017 and 2018. The results showed that:with delayed sowing date, the growing process slowed, the daily mean temperature and sunshine hours were lower during the flowering and bolling stages, and the effective accumulated temperature increased until it reached a peak on the sowing date of 4-June. These trends suggested that temperature and sunshine were both higher before the sowing date of 4-June. The biomass and nitrogen, phosphorus and potassium accumulation of cotton plants and reproductive organs decreased with sowing date delay. The accumulation rate in biomass and nutrient peaked even earlier, on the sowing date of 15-May, 25-May, and 4-June than on sowing date of 14-June and 24-June. As the sowing date was delayed, boll number and lint yield both decreased. Compared with the 15-May sowing date, the lint yields decreased by 13.1%-16.9% for sowing dates of 25-May and 4-June, and by 26.9%-33.5% and 58.2%-62.0% for sowing dates of 14-June and 24-June, respectively. Nutrient uptake of nitrogen, phosphorus, and potassium for 100 kg lint yield increased with sowing date delay, while the nutrient use efficiency decreased. The fiber quality was better for sowing dates of 4-June and 14-June than for other sowing dates. In summary, sowing from 15-May to 4-June is suitable to achieve high yield in short-season cotton field-seeded after barley or oilseed rape harvest in the downstream Yangtze River Valley. Sowing later during this period would, on the other hand, lead to high fiber quality.