Effects of different potassium doses on growth of Chinese kale [Brassica alboglabra Bailey) and possible use of SPAD forquick diagnosis

摘要

Chinese kale (Brassica alboglabra Bailey) production faces growing challenge from long-term over fertilizing. Potassium is the biggest demand and one of the most frequently overused nutrients for Chinese kale, inducing extensive environment and safe concern. Quick and accurate response to nutrient requirement is an effective solution. Therefore, pot experiments were conducted to study the influence of potassium fertilizer in different rates on the growth and nutrition utilization capacity of Chinesekale and the SPAD-502 chlorophyll meter was evaluated throughout season for its potential to determine the need for K fertilizer by Chinese kale. Potassium fertilizers were added to soil at five levels : 0, 100, 200, 300 and 400 mg/kg soil as KC1. The Krates were found to affect the growth of the leaves and stems, morphology of roots and utilization of K nutrition. Three hundred mg/kg K significantly increased stem/leaf ratio and K content in above-ground. The highest dry weight and K utilization of whole plant were obtained under 200 mg/kgK conditions and were associated with increased root length and surface area compared to other treatments. In quik-leaf-growth stage, relatively strong correlationship between SPAD and dry weight, K fertilizer amount and K content in stem was observed. These data provide preliminary results to establish the final proposal for environmentally and economically use of K fertilizer and it is the first step to further develop precision agriculture for vegetables in tropic and sub-tropical regions of China.