Effects of water and nitrogen coupling on photosynthetic characteristics and yield of winter wheat in film hole irrigation fields

Investigating impacts of combined moisture and nitrogen on photosynthetic characteristics and yield of winter wheat by film hole irrigation, this study conducted the planting experiment of winter wheat with film hole irrigation under different irrigation amount so as to study fertilizer amount was studied and the effects of winter wheat plant height, chlorophyll content, rate of photosynthesis, rate of transpiration, stomatal conductance and other photosynthetic characteristics. Analyses of yield and water use efficiency of winter wheat under water and nitrogen interaction were carried out. The reports showed that under film hole irrigation, the plant height of winter wheat initially increased and thereafter decreased with increasing the moisture content, with the plant height of the medium water treatment being significantly higher than that of the other ones, and this trend gradually decreased with the increasing fertilization application, indicating that the variation of water failed to significantly affect plant height under high fertilizer level (P > 0.01); the increase of nitrogen application was beneficial and could improve the sensitivity of winter wheat to environmental changes, which was reflected in the increase of both net photosynthetic rate and transpiration rate (P < 0.01), and it could last for a long time to keep the stomatal conductance of winter wheat at a high level constantly; the diurnal variation of photosynthesis in high water and medium nitrogen presented a "unimodal-type" curve; the diurnal change of photosynthesis in medium water and medium nitrogen as well as in low water and high nitrogen showed a "bimodal" curve; the water use efficiency of winter wheat leaves in medium nitrogen and high water could be significantly increased when the irrigation amount was the same (P < 0.05); water-nitrogen scheme for medium nitrogen and medium water was the best solution to save water, reduce nitrogen and increase grain yield under the experimental conditions of film hole irrigation of winter wheat. Its grain yield was 3,763.01 kg/ha(2) and the total water utilization efficiency and irrigation water utilization efficiency reached the maximum. The results of this study can provide scientific basis for water and fertilizer management of winter wheat under the film hole irrigation mode.