Effect of color shading-nets on the growth and physiological characteristics of Chieh-qua Seedling

With uncovered net as a control, the effect of color shading-nets (red net, blue net and silver net) and ordinary black net on growth and physiological characteristics of Chieh-qua (Benincasa hispida Cogn.var. chieh-qua How.) seedling were studied. The result showed that, shading-net covering reduced light intensity and temperature, and increased air humidity of the seedling environment, compared with the control. Shading-net covering increased plant height, stem diameter, leaf area and biomass of Chieh-qua seedling, among which covering of blue and silver shading-nets were superior to the others. Root/shoot ratio and strong seedling index were the biggest under blue net treatment, thus it indicated that blue net covering promoted seedling haleness. Specific leaf weight of Chieh-qua seedling was reduced by covering shading-net. In addition to silver net, leaf chlorophyll and carotenoids content were significantly increased by another 3 covering shading-nets. Relative conductivity (RC), malondialdehyde (MDA) content, superoxidase dismutase (SOD) and peroxydase (POD) activity of Chieh-qua seedling leaf were significantly reduced by shading-net covering. This indicated that shading-net covering in seeding nursery alleviated the stress of intensive light and high temperature, and thus increased the integrated seedling quality. Blue shading-net performed the best among all covering shading-nets.