Zhou Zhi-guo

Effect of Nitrogen Rates and Flowering Dates on Fiber Quality of Cotton (Gossypium hirsutum L.)

Nitrogen (N) supply during boll setting and maturation period of cotton can be critical in determining fiber quality. The study aims to investigate the relationship between N rates and formation of fiber length, strength, maturity and micronaire in bolls with different flowering dates. Field experiments were conducted using two cotton cultivars (Kemian 1 and NuCOTN 33B) and three N fertilization rates (0, 240, and 480 kg N ha -1 ) in Nanjing and Xuzhou in 2005 and in Anyang in 2007, China. The fiber length, strength, maturity, micronaire, and N concentration per unit area (N A) of the subtending leaf of cotton boll were analyzed. N fertilization rates, flowering dates, and N fertilization rates × flowering dates significantly (P ≤ 0.05) affected N A and the formation of fiber length, strength, maturity and micronaire. N fertilization rates affected fiber quality by influencing NA which was significantly related to rate and duration of the fiber quality formation process. The optimal N A for fiber quality formation was varied. For bolls flowering before August 25, when mean daily temperature during boll maturation period (MDT BMP ) was higher than 21°C, NA in the 240 kg N ha -1

Accumulation characteristics of biomass and nitrogen and critical nitrogen concentration dilution model of cotton reproductive organ

Abstract Several nitrogen (N) field experiments were carried out in Nanjing and Anyang, China, to study the dynamic characteristics of biomass accumulation and N uptake, and to define the dilution curve for critical N concentration in cotton reproductive organ over the growth period. The results show that the total biomass and N accumulation were affected significantly by the rate of N application, exhibiting a sigmoid curve over time. The beginning time of fast N accumulation was 1–5 d earlier than that of biomass accumulation. The cotton lint yield was correlated with N concentration in the reproductive organ and fluctuated with varying N concentration, indicating the existence of luxurious N consumption in the cotton reproductive organ. The N concentration increased with increasing N application rates, and decreased gradually during the growth period. The relationship between biomass and N concentration can be described with a power equation. The patterns of the N concentration dilution model were consistent at both experimental sites, but the model parameter values of a differed. The results presented in this paper indicate that a critical N concentration dilution curve for cotton reproductive organ is independent of ecological region and can be described with a power equation.

Sowing date and boll position affected boll weight, fiber quality and fiber physiological parameters in two cotton (Gossypium Hirsutum L.) cultivars

To study the effects of sowing date and boll position on fiber quality and the physiological mechanism, field experiments were conducted using two cotton cultivars (Kemian 1 and Sumian 15) with two sowing dates (normal sowing date 25 April, and late sowing date 25 May) at Nanjing (118°50′E, 32°02′N), Jiangsu, China, in 2006 and 2007. Cotton bolls were divided into three parts (low, middle and upper) according to the fruiting branch symbodial positions. Boll weight, fiber quality (bundle strength, span lengths, micronaire), and fiber physiological parameters (cellulose content, callose content, and sucrose transformation rate) were detected, respectively. Boll weight and fiber strength were affected by sowing date, boll position, and sowing date × boll position. Comparing to the normal sowing date, late sowing date declined boll weight, fiber strength, cellulose content, and sucrose transformation rate. The cellulose content and sucrose transformation rate changed with boll position, and consequently resulted in the change of boll weight and fiber strength. In normal sowing date, cotton boll in middle positional sympodial branch had the highest cellulose content, sucrose transformation rate, boll weight, and fiber strength. In late sowing date, cotton boll in low positional sympodial branch had the highest cellulose content, boll weight and fiber quality. The results indicated that the change of fiber yield and quality in sowing dates and boll positions were because the synthesis of cellulose, callose and sucrose were changed. Increasing the cellulose content and sucrose transformation rate can improve yield and fiber quality in late sowing date or sub-optimal environmental conditions.

Effect of Planting Date and Boll Position on Fiber Strength of Cotton (Gossypium hirsutum L.)

The effect of planting date and boll position on cell wall thickening of cotton fiber and development of fiber strength were studied by comparing the time course of the activity of key enzymes β-1,3-glucan synthase (callose) and sucrose synthase (SuSy) involved in cellulose biosynthesis, cellulose content and the indices of fiber structure X-ray diffraction of the fiber that developed at different planting dates or boll positions. The results showed that during the fiber cell wall thickening and fiber strength formation stage (25-50 days post-anthesis, DPA), there was an interactive effect between planting date and boll position. Different planting dates resulted in different mean daily temperatures during 2550 DPA (T DPA 25-50 ), which was always an important factor that influenced fiber strength, while the impact of boll position in different temperature conditions was variable. When TDPA 25-50 was above 22.0°C, boll position might affect the cell wall thickening process and the fiber strength, while when T DPA25-50 was lower than 20.0°c, boll position affect little. The optimum conditions for the development of fiber cell wall thickening and the formation of fiber strength may be the eighth nodal position of the fruiting branch (PFB) and with the TDPA 25 -50 of about 26.0°C. Research Article