Abstract:

【Objective】 To study the effect of plant physiological age on biomass and nitrogen accumulation in cotton bolls and their relationship with boll quality. 【Method】 The experiments were carried out in Xuzhou (117°11′E, 34°15′N) and Anyang (114°13′E, 36°04′N) with two cotton cultivars Kemian 1 and NuCOTN as materials. The biomass and nitrogen accumulation of cotton bolls were studied with different fruiting positions under the same temperature conditions by setting different sowing dates (25th April and 25th May). 【Result】 Under younger plant physiological age conditions (bolls developed on lower positional fruiting-branches), the start time, the rate and the duration of the rapid biomass and nitrogen accumulation period was earlier, higher and longer than that under higher plant physiological age conditions (bolls developed on middle positional fruiting-branches), respectively, while the total biomass and nitrogen accumulation of the bolls with different plant physiological conditions were not different. Consequently, except that the fiber strength developed in the middle positions was higher than that in lower positions, other fiber qualities (fiber length and micronaire) and cotton seed qualities (the gross protein content and gross oil content) were not different. 【Conclusion】 These results suggested that the variation of plant physiological age seemed not to change the total biomass and nitrogen accumulation in cotton bolls, but may change the process of them. Fiber strength might be the most sensitive fiber character to the variation of plant physiological age. And higher fiber strength in the middle positions than that in lower positions might be mainly due to its more tempered biomass and nitrogen accumulation progress.

Key words: cotton, plant physiological age, biomass, nitrogen, accumulation, cotton boll quality