Effects of Water and Nitrogen Supply on Dry Matter Accumulation,Nutrient Uptake and Distribution in Greenhouse Winter-spring Cucumber

A two-year experiment with different irrigation rates and nitrogen application rates was conducted in greenhouse winter-spring cucumber.Dry matter accumulation,nutrient uptake,water and nitrogen use efficiency and yield were investigated with treatments in furrow irrigation patterns under film covered.The results showed that characteristics of dry matter accumulation and nutrient uptake were similar and looked like S curve.The fruiting stage was the critical stage for dry matter accumulation and nutrient uptake.The root dry matter was not affected significantly by different water and nitrogen application patterns,but leaves and stems and fruits dry matter were affected during fruiting stage.Optimized water and nitrogen application rates improved the dry matter accumulation and the ratio to the total dry matter,especially the fruit accumulation,but decreased the ratio of root to shoot.The nutrient uptake was absorbed as N 396~490 kg/ha,P 93~127 kg/ha,K 516~529 kg/ha,with an order of KNP to attain the cucumber yield of 150 to 200 t/ha.The N ∶ P ∶ K ratio of nutrient uptake was 1 ∶ 0.21 ∶ 1.17 for optimized water and nitrogen application rates.Both nitrogen fertilization and water-reduced could improve the dry matter,nitrogen uptake.Compared with conventional water and nitrogen supply,optimized water and nitrogen application rate improved dry matter accumulation,nitrogen uptake and the ratio of nitrogen in fruit.The ratio of P and K to N were increased but the uptake of P and K were decreased for optimized treatment.So optimized water and nitrogen supply improved nitrogen use efficiency,partial nitrogen production efficiency,and the water use efficiency,while decreased luxury uptake of phosphorous and potassium for cucumber.