Physiological characteristics of leaf growth and yield of cucumber under different watering and fertilizer coupling treatments in greenhouse

Physiological characteristics of cucumber leaves and yield under different watering and fertilizer coupling treatments were determined with completely random experiment setup in greenhouse on Loess Plateau. The results showed that in all treatments leaf area became bigger, and those parameters such as leaf expansion speed (LES), leaf water level, the amount of free proline (PRO), malondialdehyde (MDA), yield and water use efficiency (WUE) were increased initially and then decreased at the fruit-bearing stage. When soil water content was at the same level, leaf area, leaf water level, WUE and yield were greater in the high fertilization treatment Fh (600 kg/hm2 N and 420 kg/hm2 P2O5 ) than in low fertilization treatment Fl (420 kg/hm2 N and 294 kg/hm2 P2O5). The yield was enhanced with soil water content increasing at low fertilization level; while at high fertilization level, the output rose and then declined with soil water content increasing. And the WUE in the two fertilization levels decreased with the soil water content increasing. The net photosynthetic (Pn) rate and transpiration (Tr) of the cucumber leaves in the treatment of WmFh (＞75%-90% soil water content, 600 kg/hm2 N and 420 kg/hm2 P2O5) were significantly greater than in other treatments, indicating that the water and fertilizer supply could meet the cucumber needs, making leaves grow vigorously and photosynthesis capability stronger, and attain high yield and save the water resource.