Studies on the Cultivation of Upland Cotton, Especially in Regard to Its Blooming and Ripening : III. The effects of different sowing dates on the numbers of convolution in cotton fibre

[摘要] The experiments on the effects of blooming and ripening states of Upland cotton (Kanno No.1) on the numbers of convolution in cotton fibre of bolls arranged at vertical position were conducted by varying the sowing dates from May 7 to July 5 at 15 days intervals. The results obtained were as follows; 1) The numbers of convolution tend to decrease as the sowing dates are later and the ripening days become longer, but at later sowing after June they become constant regardless of vertical positions or of ripening days. 2) In the cotton fibres with ripening days more than 74∼78 days, the numbers slowly decrease in May 7 sowing but take a constant value (20) in May 22 sowing. 3) In the fibre required 74∼78 days for ripening, the average accumulated temperatures per day for cell-wall thickning were calculated as about 19.5 °C, and this is minimum temperature required to the secondary thickning of cellulose of cotton fibre. 4) The changes of the numbers of convolution do not coincide with our presumption even under optimum conditions except May 7 sowing with normal chang. So, we assume that the cell-wall thickning of cotton fibres is more directly affected by vegetative growth of plant itself than temperature. Then, the early sowing is preferable for the increase of the numbers of convolution because of it will bring about the complete vegetative development of cotton plant

[学科分类] 农业科学（综合）