Effect of intercropping summer and spring maize on photosynthesis and yield of summer maize Effects of excessive nitrogen supply on productivity of winter wheat Characteristics of photosynthetic productivity and water-consumption for transpiration in Pinus densiflora var. zhangwuensis and Pinus sylvestris var. mongolica Response characteristics of photosynthetic and physiological parameters in Ziziphus jujuba var. spinosus seedling leaves to soil water in sand habitat formed from seashells Threshold Effect of Photosynthesis in Forsythia suspense to Soil Water and its Photosynthetic Productivity Grading in Spring and Summer Evaluation of Important Traits of Different Clones of North-Typed Populus deltoides Photosynthetic Productivity of Seedlings of Three Larch Species in the Mountainous Area of Hebei Province Effects of Different Paddy Field Drainage Degrees and Panicle Nitrogen Fertilizer Managements on Photosynthetic Productivity and Nitrogen Utilization of Rice under Triangle-Planted System of Rice Intensification