Response of leaf area expansion and photosynthetic characteristics of cucumber to soil water status in greenhouse

The potted experiment of cucumber in greenhouse was conducted to study the effects of soil water status on leaf area expansion and photosynthetic characteristics.The results show that there are three growing phases during leaves expansion of cucumber,exponential growth phase(EG),linear scale growth phase(LSG)and stability constant growth phase(SCG).With the soil water content increasing,the leaf area(LA)enlarges significantly,and the maximum of leaf growth rate(LGR)appears obviously early.The relative expansion rate(RER)of leaves increases at the EG phase,but gradually reduces at the LSG and SCG phases.Soil moisture significantly influences the leaf expansion and photosynthetic characteristics.During the proceeding of leaf growth,the chlorophyll content and net photosynthetic rate(Pn)increase gradually with significant differences among treatments.The diurnal variations of Pn of all treatments demonstrate a single peak curve.The apparent quantum yield(AQY)and carboxylation efficiency(CE)of cucumber leaves among different treatments show significant differences.