Chen BingLin

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

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

Image Segmentation Technique of Field Cotton Based on Color Threshold

The goal of cotton production in China is to improve corresponding rate of cotton quality grade, foreign fibers, adulteration, and cotton baling inconsistent phenomenon to decrease continuously. With the background, machine vision and pattern recognition technologies are introduced into traditional picking task to discriminate maturity degree and grade of quality of field cotton, which will solve the problem of picking cotton by the way from source, so that various cotton varieties can be adapted, pollution caused by agriculture chemicals can be avoided, labor cost can be reduced and agriculture cost can be decreased. In order to segment field cotton images exactly, we regarded cotton and its background as two classes and segmented them based on their color threshold. A total of 20 000 white, yellow, and stain cotton pixels and 20 000 background pixels of soil and cotton plant, including cotton bracteole, leaf, and branch, were extracted from typical under-ripe cotton images and ripe/over-ripe cotton images with various quality grades from 1 to 7. Color threshold of two classes of cotton and its background pixels were obtained in RGB, HSI, La*b*, and Hunter color space respectively; on the basis of which cotton regions were segmented from images; and HSI and La*b* color spaces were selected respectively by using S below 28, I over 108, L over 118, a* from 123 to 134, b* below 136 with less segmentation noise which would be removed based on morphological filter. The experiment results showed that 907 cotton images were segmented with an accuracy of 87.21% and 86.33% in HSI and La*b* color space respectively. The front images were segmented with an accuracy of 90.83% and 89.98% and the side images with an accuracy of 83.33% and 82.42%. Ripe cotton images were segmented perfectly in HSI color space while under-ripe cotton images in La*b* color space, and the speed-based segmentation method with threshold covering a wide area was preferable for field cotton surroundings.