Seedbed zinc nutrition affects the early growth of transplanted oilseed rape (Brassica napus L.) in chelate-buffered nutrient solution

摘要

Previous results indicated that root pruning inhibited Zn uptake and growth of roots and shoots after transplanting suggesting that this might be the main reason why transplanted oilseed rape had an increased external Zn requirement for post-transplanting growth. The aim of the present study was to examine whether increasing the seedling Zn content at transplanting would hasten new root growth of transplanted oilseed rape and therefore would alleviate the need for increased external Zn requirement for post-transplanting growth. In a glasshouse experiment, seedlings raised at 2 rates of seedbed Zn concentration, 50 (low) and 90 (adequate) μg Zn kg-1 soil, were transferred at 4-leaf stage to chelate-buffered nutrient solution containing low and adequate levels of Zn-HEDTA (0.02 and 5.0 μM) with or without pruning roots (0, 50%) immediately before transplanting. Plants grown from the adequate seedbed Zn had increased post-transplanting growth especially of roots. Shoots and roots responded positively to increased solution Zn supply after transplanting, and root pruning suppressed root and shoot dry matter, root length, and root hair density especially at low solution Zn. The effects of seedbed and post-transplanting Zn supply on shoot and root growth were additive after 20 days of growth. Hence, it was concluded that adequate Zn in the seedbed hastened root and shoot recovery after transplanting. However, increasing Zn concentration and content in nursery seedlings could only partially alleviate the inhibition of post-transplanting growth in low Zn media.