Effect of shading cabbage seedlings on their physiological processes and rooting ability after transplanting to the nursery

Abstract

Cabbage seedlings were shaded to see what effects the treatment had on photosynthesis, not respiration carbohydrates content, invertase activity, and their rooting ability after being transplated into the nursery. The effects of irrigating shaded plants with a sugar solution on root respiration and rooting ability were also investigated. 1. The rate of photosynthesis and root respiration declined in shade plants. Seedling had less carbohydrate in the top and roots as compared with those exposed to light. 2. In plants transferred to shading plot, root respiration decreases rapidly, but the decline in invertase activity lagged behind that of root respiration. 3. Lowered respiration activity in roots caused by the shade treatment was restored by irrigating with a sucrose solution, plants treated with sucrose solution had deeper and larger root distribution than did those in the - sucrose plot. From these results, we conclude that rooting ability after transplating cabbage seedling to a nursery depends largely on carbohydrate content in the roots during the seedling stage. If nursery plants are subjected to low light intensity conditions, carbohydrate levels in the roots decrease because of lower photosynthesis activity. This decreased carbohydrates content causes a decrease in activity of those enzymes associated with respiration. Diminished photosynthesis and lowered enzyme activities inhibit roots respiration. Consequently, a larger amount of energy is consumed for basal metabolism for survival which detracts from root formation after planting.