Effects of Water Extracts from Different Soilless Cultivation Media on Growth and Photosynthetic Characteristics of Pumpkin Seedlings

The examination of the water extracts effects from difffernt soilless cultivation media on crop growth could provide guidelines for recycling the use of soilless cultivation media.The growth and physiological parameters of pumpkin seedlings from water extracts of soilless cultivation media were analyzed and discussed.The soilless media included alternate cropping (Y1),2-year continuous cropping (Y2),3-year continuous cropping (Y3),and distilled water was designed as (CK) treatment.Compared with CK treatment,pumpkin seedlings with Y1 treatment showed a significant increase in all following parameters,they were plant height,fresh and dry weight of aboveground plant,fresh and dry weight of underground plant,dry weight of plant root-shoot ratio,chlorophyll a,chlorophyll b,chlorophyll (a+b),chlorophyll a/b,stomatalconductance (Gs),netphotosynthetic rate (Pn),instantaneous water use efficiency (WUE),instantaneous carboxylation efficiency (CE) and instantaneous light energy utilization(LUE).However,pumpkin seedlings with Y2 and Y3 treatments showed a decrease in fresh and dry weight of aboveground plant,fresh and dry weight of underground plant,dry weight of plant root-shoot ratio,chlorophyll a/b,Tr,Gs and Ci.Moreover,pumpkin seedlings with Y3 treatment showed a significant decreased(p<0.05) plant root-shoot dry weight ratio by 33.3%,Pn by 20.9%,CE by 11.1% of and LUE by 16.6%,respectively.Y3 teatment could negatively affect seedling growth index and photosynthetic parameters to pumpkin seedlings.