| The experiment was conducted during 2014-2015 growing season of winter wheat(Triticum aestivum L.) at the Agronomy Experimental Station(36°09?N, 117°09?E) of Shandong Agricultural University. Winter wheat(Jimai 22) was hand-planted at 200×104 ha-1. The field experiment in a randomized complete block design with three replicates. The three planting patterns were: 30 cm uniform row planting pattern(U), “20 + 40” cm furrow planting pattern(F), “20” cm double-double planting pattern(DD). Three irrigation treatments applied: irrigating 100 mm each at jointing(growth stage 35, GS35) and heading(GS49) stages, and total irrigation amount was 200 mm(I1); irrigating 100 mm only at GS35 and total irrigation amount was 100 mm(I2); irrigating 50 mm each at GS35 and GS49, and total irrigation amount was 100 mm(I3).The experiment focused on the connective and responsive mechanisms between farmland microhabitats and hydraulic signals. The dynamic changes in population structure, field microclimate, soil water, and hydraulic signals of plants under different farmland microhabitats of the same density, and analyzed of the relationship between water signals and soil water characteristics as well as crop growth. This study will provided important information on the characteristics of crop water signal to different planting patterns and irrigation, and provide some theoretical basis and technical support for water saving agriculture.1 Changes of farmland microclimateDuring GS35-GS80 of winter wheat, DD planting pattern decreased air temperature, but increased relative humidity compared with U and F. The daily change of air temperature showed “?” type, and daily change of relative humidity was opposite with that of air temperature. For the three irrigation treatment, I1 had the lowest air temperature and the highest relative humidity; compared with I2, I3 decreased air temperature and increased relative humidity. Relative humidity was significantly negatively correlated with air temperature, whereas soil temperature was significantly positively correlated with air temperature(P < 0.01). The trend of soil temperature and air temperature is consistent, but soil temperature showed some lag effects; with the depth of the soil, the lag effect is more obvious. The order of the average soil temperature was I1 < I3 < I2, and compared with I2, I3 can significantly reduce soil temperature.2 The effects of planting pattern and irrigation on soil water signalsPlanting pattern, irrigation and the interaction between them significantly affected soil water content(P < 0.05). Soil water content decreased through growing season. The soil water content of I1 was the highest, and compared with I2, I3 mainly improved the soil water content at different soil layers in the late growth stage. The order of soil water content at GS35 was I1 > I2 > I3, and the order was I1 > I3 > I2 at the GS49 and GS71. DD planting pattern significantly increased the soil water content at different soil layers(P < 0.05), and significantly increased the soil water storage and soil water potential(P < 0.05). A significantly positive correlation was observed among the soil water, soil water storage and soil water potential(P < 0.01). I1 significantly increased soil water storage and soil water potential, and there was no significant difference between I2 and I3, but I3 improved soil water potential in the late growth. DD planting pattern and I3 treatment decreased evapotranspiration at different growth stage, and then increased water use efficiency(WUE). DD planting pattern significantly decreased total evapotranspiration than that of F and U(P < 0.05); the order of total evapotranspiration for different irrigation treatment was I3 < I2 < I1, I3 was significantly lower than those of I2 and I1 irrigation treatments(P < 0.05). There was a quadratic equation of yield and evapotranspiration.3 The effects of planting pattern and irrigation on leaf water signalsThe osmotic potential(?) and water potential(?w) showed significant negative correlation with growth stage. For F, U and DD planting pattern, ? values were-1.54,-1.55,-1.49 MPa, ?w values were-1.86,-1.91,-1.80 MPa, relative water content(RWC) values were 79.5%, 78.5%, 81.9%, abscisic acid(ABA) values were 22.9?24.5?21.3 ng g-1, so DD planting pattern increased ?, ?w and RWC and decreased ABA. For the I1, I2 and I3 treatment, ? values were-1.48,-1.56,-1.54 MPa, ?w values were-1.78,-1.94,-1.86 MPa, RWC values were 82.4%, 77.6%, 79.9%, ABA values were 21.7?23.6?23. 5ng g-1. I1 treatment had the highest ?, ?w and RWC and the lowest ABA, and I3 improved all kinds of indicators than I2, especially in the late growth stage. The daily change of ?w was significantly negatively with time, and the ?w at GS49 was higher than that of GS71. Yield was positively correlated with ?w, and significantly positively correlated with ? and RWC(P < 0.05), whereas negatively correlated with ABA; therefore, with the increasing of ?w, ? and RWC, decreasing ABA, yield was increased. WUE was significantly positively correlated with ?w, ? and RWC(P < 0.01), significantly negatively correlated with ABA(P < 0.01), therefore, with the increasing of ?w, ? and RWC, decreasing ABA, WUE was increased.4 Population develop dynamicsWith the advance of the growth stage, the stem number of winter wheat increased firstly and then decreased. DD planting pattern and I3 treatment increased spike number in the late growth stage, and had obvious advantage in the population develop. DD significantly improved the dry matter in different organs and total dry matter(P < 0.05), indicating that the DD can not only improve the total amount of dry matter accumulation, but also can adjust the amount of dry matter in different organs. The order of dry matter in leaves was I1 > I2 > I3, and the order of stem, spike and total dry matter was I1 > I3 > I2. I1 significantly increased the dry matter in different organs and total dry matter, and I3 increased the spike dry matter and total dry matter.5 Yield and water use efficiencyPlanting pattern, irrigation and the interaction between them significantly affected yield and WUE(P < 0.05). DD significantly improved yield, WUE and harvest index. For the I1, I2, I3, the average values of the yield were 804?726?755 g m-2, the yield of I1 was significant higher than that of I3(P < 0.05), and I3 was significant higher than that of I2(P < 0.05); the WUE of I3 was significant higher than those of I2 and I1(P < 0.05); the harvest index of I3 was significant higher than that of I2. DD increased the spikes m-2, grains spike-1 and thousand grain weight, and spikes m-2 was the most obvious. Compared with I2, I3 significantly increased the spikes m-2 and thousand grain weight(P < 0.05). DD increased the plant height and spike length; I1 increased the plant height, spike length, spikelet number and decreased sterile spikelet number, indicating that higher irrigation amount is beneficial to improve the yield components; compared with I2, I3 significantly increased the plant height and decreased sterile spikelet number(P < 0.05), and increased spike length and spikelet number spike-1. Yield was significantly positively correlated with spike length, spikes m-2 and grains spike-1(P < 0.01), and significantly positively correlated with plant height, spikelet number spike-1 and thousand grain weight(P < 0.05), and significantly negtively correlated with sterile spikelet number spike-1(P < 0.01). |
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