[Effects of integration of micro-sprinkler irrigation and nitrogen on growth and development of winter wheat and water and fertilizer use efficiency].

Under the same irrigation amount and nitrogen application rate and after the corn stalks being returned to the field in the wheat-corn crop rotation area, we examined the effects of the integrated water and nitrogen mode of micro-sprinkler irrigation on the growth and development and water and fertilizer use efficiency of winter wheat. In 2016-2018, we conducted a two-year field experiment with six types of micro-sprinkler irrigation water and nitrogen integration modes and seven treatments during the growth period, and investigated the population dynamics, dry matter accumulation transfer during the filling period, and nutrient accumulation during the mature period. There were three modes of irrigation, W1(overwintering water + jointing water + grouting water, 600 m3·hm-2 for each), W2(overwintering water + regreening water + jointing water + grouting water, each for 450 m3·hm-2), and W3(600 m3·hm-2 each for overwintering water and jointing water, and 300 m3·hm-2 each for regreening water and grouting water); two modes of nitrogen application, N1(basic nitrogen application 60% + jointing water nitrogen topdressing 40%) and N2 (basic nitrogen application 60% + jointing water nitrogen topdressing 30% + grouting water nitrogen topdressing 10%); with no fertilization under W1 as control (CK). The results showed that: 1) The amount of overwintering water irrigation increased from 450 m3·hm-2to 600 m3·hm-2, which was beneficial to the total number of both stems and panicles in the overwintering period and consequently to yield. Irrigation in the regreening stage increased the total number of stems at the jointing stage, but with limited effect on the number of panicles. Applying more nitrogen at the jointing stage increased the number of stems per plant, but decreased that of panicles. 2) Four times of irrigation (W2 and W3) during the growth period, combined with nitrogen (N2) in the jointing and filling phases, were conducive to the accumulation of dry matter during the filling period, increasing the number of grains per spike and 1000-grain weight, thereby increasing yield. 3) Compared with the three times of irrigation treatment during the growth period, water consumption and absorption of nitrogen, phosphorus and potassium under the four times of irrigation treatment were increased, and water and fertilizer use efficiency was improved. In W2 and W3 under the treatment of four times irrigation, water consumption of N2 during the growth period was lower than N1, absorption of nitrogen, phosphorus, and potassium were higher than N1, and the irrigation and utilization of nitrogen, phosphorus and potassium were significantly improved, of which W3N2 had the best effect. Therefore, W3N2 treatment (sowing winter wheat after returning corn stalks to the field, irrigating four times during the growth period of micro-sprinkler irrigation, increasing the amount of overwintering water and jointing water irrigation to 600 m3·hm-2, combined with jointing water and filling water topdressing nitrogen fertilizer) increased spike number and 1000-grain weight of wheat andincreased yield, with the highest water and fertilizer use efficiency. It was the best water and nitrogen management mode for the integration of micro-sprinkler irrigation and water and fertilizer for winter wheat in southern Shanxi.