Characteristics of growth and development of cotton with different seedling ages raised in small nutritional pot.

The experiment of seedling raised in small nutritional pot was conducted in field with different transplanting date.The purpose was to investigate the survival rate and growth of seedlings with different ages.The results were as follows: The survival rate after transplanting was up to 97.1% for seedlings at 15 d,20 d and 25 d age,and declined at 30 d age.For the seedlings at 20 d age,the dry matter weight was moderate and the growth rate was high at the 14th day after transplanting.For the seedling at 20 d age,the root weight was low and the growth rate of above-ground organs was negative at the 14th day after transplanting,compared to the seedling at 15 d age.The seedlings of 15 d age were less in dry matter and had a higher growth rate at the 14th day after transplanting,while the situation for the seedlings at 30 d age was in reverse.Therefore,25 d of seedling age was the turning point at which the growth rate for seedling turned slow.It was coordination with vegetative and reproductive organs for seedlings at 20 d or 25 d,and correspondingly,the yields were high.The reproductive growth was weak and late for the seedlings at 15 d for its uncoordinated growth between vegetative and reproductive organs.The yield of seedlings at 30 d age was lower than that at 20 d or 25 d.The results demonstrated that the appropriate seedling age is important for growth and yield for seedling raised in small nutritional pot.