Effects of water and fertilizer coupling on yield and water use efficiency in greenhouse potted cucumber

To study the influences of soil water content and fertilization levels on growth and development of greenhouse cucumber (Cucumis sativus L.) and their mutual coupling effects, a controlling pot device with a negative pressure water supplying is used to control different soil moisture by setting the water supply tension(WST) of the device at different levels. Three WST levels, i.e. 3 kPa (W1), 5 kPa (W2), and 7 kPa (W3), and three fertilization rates, i.e., N600P300K300 kg/ha (F1), N900P450K450 kg/ha (F2), N1200P600K600 kg/ha (F3), are designed. Results show that the soil water contents at the W1, W2 and W3 treatments were 26.25%, 20.81% and 15.35%, respectively. Plant growth rate and yield increased with the increasing of soil moisture at the same fertilization rate, the value order is W1＞W2＞W3. In W1 and W2 treatments, plant growth rate, photosynthesis, dry mass, yield and WUE are increased with the increasing of the fertilization rate (F3＞F2＞F1). Furthermore, the increasing of fertilization to enhance the WUE does not take the increasing of plant water consumption as the price. However, dry mass，leaf photosynthesis and yield value of cucumber under W3 treatment is F2＞F1＞F3. High fertilization level (F3) has a negative effect on the cucumber plant growth under low moisture level (W3). The experiment results also indicate there are significant effects of interaction between water and fertilizer on yield and WUE of cucumber.