Changes with age in physiological properties of roots in plug nursery seedlings of cabbage [Brassica oleracea capitata]
2001
Fukuoka, N. (Ishikawa-ken. Sand Dune Agricultural Experiment Station, Unoke (Japan)) | Yoshioka, H. | Shimizu, E. | Fujiwara, T.
Changes with seedling age of cabbage (Brassica oleracea L. var oleracea) in respiration rate, carbohydrate content and invertase activity of the seedling roots were investigated in relation to the physiological causes of poor root formation after planting of aged seedlings raised by means of plug trays. 1. Drag resistance of plants measured by an autograph at day 4 after planting increased with seedling age at planting until 30 days after sowing, and decreased gradually there after. 2. Root respiration rate per gram dry weight were high and relatively constant during the first 30 days after sowing, and decreased rapidly thereafter. 3. The decrease in root respiration rate was accompanied by reduction of invertase activity, which was very rapid during 30 to 60 days after sowing and relatively slow thereafter. 4. Progress of seedling age from 40 to 60 days after sowing resulted in a marked increase in the content of glucose and particularly sucrose in the root. These sugar concentrations in the root sampled from 40-day-old seedlings were about 2 times higher than those from 60-day-old seedlings. The experimental results reveal that the progress of seedling age raised in plug trays causes the decrease in respiration rate in th root as a result of the lowered enzyme activity and carbohydrate utilization associated with respiring in the root. These physiological inactivation in the root with aging result in the reduction in rooting ability, and then the aged cabbage seedlings have poor root formation after planting.
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