The influence of N concentration in pre transplant nutrient solution on the N use efficiency and dry mass partitioning of pepper ( Capsicum annum L.) seedlings.

摘要

The influence of nitrogen concentration in nutrient solution on N use efficiency (NRE) and dry mass partitioning in the nursery stage of pepper (Capsicum annum L.) seedlings were estimated in experiments conducted in a plastic greenhouses. Graded seeds of cv. Ringo F₁, were individually sown in to foam trays filled with vermiculite. Different N concentration were applied in the nutrient solution (100, 150, 200 and 250 mg L-1), while P and K were respectively 40 mg L-1 and 250 mg L-1 in all treatments. The necessary microelements were also added to the nutrient solutions and equal quantities of 20-50 ml plant-1 were periodically supplied, each module. Root, stem and leaf dry matter were weighted and, the stem length and plant leaf area were periodically measured. The stem elongation rate, the leaf expansion rate, root to whole plant dry weight ratio (RWR), root to shoot dry weight ratio (RSR), and the respective fractions of roots, stems and leaf dry mass against total plant weight (RMF, SMF, LMF) were calculated. N content in the dry matter of plants was analysed and cumulative NRE values were estimated. The increase of nitrogen concentration in the nutrient solution produced a progressive increase of the whole plant dry weight, but meantime a steady decrease of root dry weight versus total plant dry weight (RMF), and of root dry weight versus shoot dry weight was observed. The stem mass fraction (SMF), seems to be the most responsible fraction of the above ground mass weight increase. N content in the plant dry matter was increased with increasing N solution's concentration, but NRE values were gradually decreased. Meantime, NRE values became higher parallel with the gradual increase of the plant root volume and leaf area index.