Effect of irrigation amount on photosynthesis and dry matter accumulation of maize in tasseling-silking stage

【Objective】 Maize is a main staple crop cultivated in central and Northern China but it requires irrigation at certain stages during its growth. In this paper, we present the findings of an experimental study on the effect of irrigation amount on photosynthesis and dry matter accumulation of the crop during its tasseling-silking stage. 【Method】 The field experiment was conducted in the long-term experiment established in 2018 at the experimental base of the academy of agricultural and animal husbandry sciences of Inner Mongolia Autonomous Region. The experiment compared six irrigation amounts: 315 m3/hm2 (W1), 645 m3/hm2 (W2), 945 m3/hm2 (W3), 1 275 m3/hm2 (W4), and 1 605 m3/hm2 (W5); the control was rain-fed (W0). During the experiment, we measured photosynthetic characteristics and dry matter accumulation of the crop in each treatment. The photosynthetic characteristics and its correlation with dry matter accumulation were calculated by fitting the response curve parameters to a non-right-angle hyperbolic model. 【Result】 The leaf SPAD in W3 was lower only than that in W4 in 2019, but in 2020 it increased by 3.96%, 5.12%, 11.10%, 12.64% and 19.90%, respectively, compared with that in W4, W2, W1, W5 and W0. In 2019 and 2020, the average daily net photosynthetic rate was the highest in W3, while in 2019, the dry weights of stems, leaves and ears in W3 were the second highest among all treatments. In 2020, the physiological indexes of the crop in W3 were higher than that in other treatments. There was no significant difference in leaf photosynthesis between W3, W4 and W5. 【Conclusion】 In central and western regions of Inner Mongolia, when the total rainfall during growing season of maize exceeded 365 mm, irrigating 945 m3/hm2 of water can effectively improve photosynthetic efficiency of the maize during its tasseling-silking stage, promote dry matter accumulation and increase grain yield.