[Effects of supplemental irrigation by measuring moisture content in different soil layers on water consumption characteristics, photosynthesis and grain yield of winter wheat].

Field experiments were conducted during 2012-2014 winter wheat growing seasons. Six irrigation treatments were designed: rainfed, W0; a local irrigation practice that irrigated at jointing and anthesis with 60 mm each time, W1; four irrigation treatments were designed with target relative soil moisture of 65% field capacity (FC) at jointing and 70% FC at anthesis in 0-20 (W2) 0-40 (W3), 0-60 (W4) , and 0-140 cm (W5) soil layers, respectively, to study the effects of supplemental irrigation by measuring moisture content in different soil layers on water consumption characteristics and photosynthesis and grain yield of winter wheat. The irrigation amounts at jointing in W1 and W4 were the highest, followed by W3 treatment, W2 and W5 were the lowest. The irrigation amounts at anthesis and total irrigation amounts were ranked as W5 > Wl, W4 > W3 > W2, the total water consumption in W3 was higher than that in W2, but had no difference with that in W1, W4 and W5 treatments, W3 had the higher soil water consumption than W1, W4 and W5 treatments, and the soil water consumption in 40-140 cm soil layers from jointing to anthesis and in 60-140 cm soil layers from anthesis to maturity in W3 were significantly higher than the other treatments. The photosynthetic rate, transpiration rate and water use efficiency of flag leaf at middle stage of grain filling from the W3 treatment were the highest, followed by the W1 and W4 treatments, and W0 treatment was the lowest. In the two growing seasons, the grain yield and water use efficiency in the W3 were 9077-9260 kg · hm(-2) and 20.7-20.9 kg · hm(-2) · mm(-1), respectively, which were higher than those from the other treatments, and the irrigation water productivity in the W3 was the highest. As far as high-yield and high-water use efficiency were concerned in this experiment, the most appropriate soil layer for measuring moisture content was 0-40 cm.

[Effects of irrigation with different length micro-sprinkling hoses on soil water distribution, water consumption characteristics of winter wheat, and its grain yield].

Taking the high-yielding winter wheat variety Jimai 22 as test material, a field experiment was conducted in 2010-2012 to study the effects of irrigation with different length micro-sprinkling hoses on the soil water distribution in winter wheat growth period and the water consumption characteristics and grain yield of winter wheat. Three micro-sprinkling hose lengths were designed, i. e., 40 m (T40), 60 m (T60) and 80 m (T80). Under the micro-sprinkling irrigation at jointing and anthesis stages, the uniformity of the horizontal distribution of irrigation water in soil increased significantly with the decrease of hose length from 80 to 40 m. When irrigated at jointing stage, the water content of 0-200 cm soil layer in each space of wheat rows had no significant difference within the 0-40 m distanced from the border initial in treatments T40 and T60. When measured at the 38-40 m, 58-60 m, and 78-80 m distanced from the border initial in treatment T80 at jointing and anthesis stages, the water content in 0-200 cm soil layer had the same change pattern, i. e., decreased with the increasing distance from micro-sprinkling hose. The water consumption amounts in 40-60 cm soil layer from jointing to anthesis stages and in 20-80 cm soil layer from anthesis to maturing stages were higher in treatment T40 than in treatments T60 and T80. However, the soil water consumption amount, irrigation amount at anthesis stage, total irrigation amount, and total water consumption amount were significantly lower in treatment T40 than in treatments T60 and T80. The grain yield, yield water use efficiency increased with the hose length decreased from 80 to 40 m, but the flow decreased. Therefore, the effective irrigation area per unit time decreased with the same irrigation amounts. Considering the grain yield, water use efficiency, and the flow through micro-sprinkling hose, 40 and 60 m were considered to be the appropriate micro-sprinkling hose lengths under this experimental condition.

[Effects of sulfur plus resin-coated controlled release urea fertilizer on winter wheat dry matter accumulation and allocation and grain yield].

A field experiment was conducted to study the effects of sulfur plus resin-coated urea fertilizer on the winter wheat dry matter accumulation and allocation and grain yield. Four treatments were installed, i.e., sulfur plus resin-coated urea (SRCU), resin-coated urea (RCU), sulfur-amended conventional urea (SU), and conventional urea (U). The coated urea fertilizers were applied as basal, and the conventional urea fertilizers were 50% applied as basal and 50% applied as topdressing. There were no significant differences in the plant dry matter accumulation and grain yield between treatments RCU and U. Under the conditions the available S content in 0-20 cm soil layer was 43.2 mg x kg(-1) and the S application rate was 91.4 kg x hm(-2), treatments SRCU and SU had no significant differences in the dry matter accumulation and allocation after anthesis and the grain yield, but the amount of the assimilates after anthesis allocated in grain, the grain-filling rate at mid grain-filling stage, the 1000-grain weight, and the grain yield in the two treatments were significantly higher than those in treatment RCU. When the available S content in 0-20 cm soil layer was 105.1 mg x kg(-1) and the S application rate was 120 kg x hm(-2), the grain yield in treatment SRCU was significantly higher than that in treatment SU, but had no significant difference with that in treatments RCU and U. These results suggested that from the viewpoints of dry matter accumulation and allocation and grain yield, the nitrogen released from SRCU had the same regulation effect as the conventional urea 50% applied as basal and 50% applied as topdressing, while the regulation effect of the sulfur released from SRCU was controlled by the available S content in 0-20 cm soil layer. When the soil available S content was 43.2 mg x kg(-1), the released sulfur could promote the dry matter accumulation after anthesis and the grain-filling, and increase the grain yield significantly; when the soil available S content was 105.1 mg x kg(-1), the released sulfur from SRCU had no significant effect in increasing grain yield. Excessive S-amendment could even induce the decrease of grain yield.