[Effects of ditch-buried organic matter and irrigation amount after anthesis on the photosynthetic characteristics and yield of maize.]

Managements of organic matter and irrigation after anthesis will increase the capacities of water conservation and supply in maize field, with consequences on photosynthetic performance and yield under water-saving condition. We analyzed the gas exchange parameters and the performance of the photosystem 2 of ear leaves, and yield of maize cultivars Zhengdan 958, under three modes of ditch-buried organic matter (no straw returned: M0 , wheat straw returned: M1 , mixtures of cow manure and wheat straw returned: M2 ) before seeding with two irrigation levels after anthesis (normal irrigation: W1 , water-saving irrigation: W2 ). The results showed that M2 treatment significantly increased photosynthetic capacity and dry matter accumulation after anthesis compared with M1 treatment. Compared with water-saving irrigation, normal irrigation enhanced the photosynthesis of ear leaves. M2 W1 treatment significantly increased net photosynthetic rate (Pn ), stomatal conduc-tance (gs ), transpiration rate (Tr ), and performance of photosystem 2 (Φpo and ωo ) of ear leaves after anthesis, while reduced intercellular CO2 concentration (Ci ). In addition, M2 W1 treatment significantly increased light utilization efficiency and maintained higher photosynthetic properties in ear leaves, and significantly increased dry matter accumulation and grain yield. Water-saving irrigation reduced photosynthetic performance of ear leaves, which declined the yield. But compared M2 with M0 , water use efficiency, grain growth rate and yield increment under water-saving irrigation were higher than those under normal irrigation. Thus, mixtures of cow manure and wheat straw returned combined with normal irrigation could significantly increase photosynthetic properties of ear leaves and dry matter accumulation, which were the major reasons for yield enhancement. Importantly, the mixture of cow manure and wheat straw returned combined with water-saving irrigation could decrease the loss of crop yield resulted from lower irrigation.