| A field experiment was conducted in Shiwang village(35 ° 24 ′ N, 116 ° 24 ′ E), Yanzhou,Shandong during the 2010 to 2014 growing seasons using the high-yielding wheat cultivar Jimai22 as test material. The objective of this experiment was to study the technology and physiological base of supplemental irrigaiotn based on measuring soil moisture in wheat, to provide theoretical basis for water-saving and high-yielding cultivation of wheat.In 2012~2014 years wheat growing seasons, soil moisture in seven soil layers, i.e. 0~20 cm(D1), 0~40 cm(D2), 0~60 cm(D3), 0~80 cm(D4), 0~100 cm(D5), 0~120 cm(D6) and 0~140 cm(D7) was measured. Two levels of soil relative water content(SRWC) in each soil layer was designed, 65% at jointing and 70% at anthesis(W1), and 70% at jointing and 70% at anthesis(W2). No-irrigation as the control treatment(W0), irrigation water of 60 mm at jointing and anthesis respectively was represented as Wck treatment. In order to study the effect of supplemental irrigation based on measuring soil moisture in the different soil layers on water consumption characteristics and grain yield of wheat.In 2010~2012 years wheat growing seasons, supplemental irrigation(SI) treatments with four sprinkling angles and three hose length sprinkling hoses were tested. SI by microsprinkling hoses with minimum sprinkling angles(i.e. the angle between the tangent of the initial water jet and the horizontal) were 35°(T1), 50°(T2), 65°(T3) and 80°(T4), respectively, the length of all micro-sprinkling hose was 40 m. SI by sprinkling hose with three hose lengths of 40 m(W40), 60 m(W60), and 80 m(W80), respectively, the sprinkling angle of all micro-sprinkling hose was 80°. The SI brought soil water content in the 0~140 cm profile to 75% field capacity(FC) at jointing and 70% FC at anthesis in 2010~2011, and 70% FC at both jointing and anthesis in 2011~2012. A rainfed treatment was designed as control. The aims were examine the effects of SI with micro-sprinkling hoses on water consumption and grain yield of winter wheat. The main results as follow: 1 Under the same target soil relative water content, the effect of supplemental irrigation based on measuring soil moisture in different soil layers on water consumption characteristics of wheat 1.1 Effect of different treatments on on water consumption characteristics of wheatIn 2012~2013 wheat growing season, under the condition of W1, the irrigation amount at jointing in D2 was significantly higher than D1, but lower than Wck, D3, D4, D5, D6 and D7 treatment. Irrigation amount at anthesis and the total irrigation amount in D2 were significantly lower than D3, D4, D5, D6 and D7, and higher than D1 treatment. The soil water consumption in 40~60 cm and 60~160 cm soil layers and the total amount in D2 were the highest, followed by Wck and D3, those in D4, D5, D6 and D7 treatment were the lowest. Under the condition of W2, the irrigation amount at jointing in D2 and Wck was significantly higher than D1, but lower than D3, D4, D5, D6 and D7 treatment. Irrigation amount at anthesis and the total irrigation amount in D2 were significantly lower than Wck, D3, D4, D5, D6 and D7, and higher than D1 treatment. The soil water consumption in 80~160 cm soil layers and the total amount in D2 and Wck were the highest, followed by D3, those in D4, D5, D6 and D7 treatment were the lowest. These results indicated that supplemental irrigation based on the soil moisture in the 0~40 cm soil layers(D2) had lower irrigation but higher soil water consumption amount than Wck, which promoted the water use of soil, and benefit for irrigation water-saving.In 2013~2014 wheat growing season, under the condition of W1, the irrigation amount at jointing in D2 was significantly higher than D1, D6 and D7, but lower than Wck, D3, D4 and D5 treatment. Irrigation amount at anthesis and the total irrigation amount in D2 were significantly lower than Wck, D3, D4, D5, D6 and D7, and higher than D1 treatment. The soil water consumption in 60~140 cm soil layers and the total amount in D2 were the highest, followed by Wck, D1 and D3, those in D4, D5, D6 and D7 treatment were the lowest. Under the condition of W2, the irrigation amount at jointing in D2 and D7 were significantly higher than D1, lower than Wck, D3, D4, D5 and D6 treatment. Irrigation amount at anthesis and the total irrigation amount in D2 were significantly lower than Wck, D3, D4, D5, D6 and D7, and higher than D1 treatment. The soil water consumption in 80~140 cm soil layers and the total amount in D2 and Wck were the highest, followed by D3, those in D4, D5, D6 and D7 treatment were the lowest. These results indicated that supplemental irrigation based on the soil moisture in the 0~40 cm soil layers had lower irrigation but higher soil water consumption amount than Wck, which promoted the water use from 80~140 cm soil layers, and benefit for irrigation water-saving. 1.2 Effects of different treatments on carbon metabolism of wheatIn the two wheat growing seasons, the leaf area index(LAI) in D2 was significantly higher than in D1, had no differences with Wck and D3 treatment after 10~20 days after anthesis(DAA). The highest LAI was obtained from D2 at 30 DAA, followed by Wck and D3, the lowest in D1 treatment. There were no significant differences in photosynthetically active radiation(PAR) between treatments at 10 DAA, but the values in D2 were significantly higher in D2, followed by Wck and D3, the lowest in D1 treatment at 20~30DAA. The PAR capture ratios at heights of 20, 40 and 60 cm in D2 were significantly higher than those in Wck, D1 and D3. From 21 to 35 DAA, the chlorophyll content index, the maximum photochemical efficiency and the actual photosynthetic activities of flag leaves in D2 were the highest, followed by Wck and D3, the lowest in D1 treatment. From 14 to 35 DAA, the photosynthetic rate, transpiration rate and stomatal conductance of flag leaves in D2 were significantly higher than those in Wck and D3, those in D1 tretment were the lowest. These results indicated that supplemental irrigation based on the soil moisture in the 0~40 cm soil layers had favourable effects on photosynthetic ability during the mid-and late grain-filling stages than irrigation with 60 mmtretment, promoted the capacity of utilization of photosynthetically active radiation, which was benefit for improving the photosynthesis of flag leaves, promoted the production of carbohydrates.In 2012~2013 wheat growing season, under the condition of W1, the dry matter(DM) accumulation in grain and stems plus sheath at maturity in D2 were significantly higher than those in D1, D4, D5, D6 and D7, but had no differ with Wck and D3 treatment. The DM accumulation in spikes axis plus glume and leaves in D2 were significantly higher than those in D1, had no differ with Wck, D3, D4, D5, D6 and D7 treatment.The DM accumulation postanthesis from D2 was significantly higher than the other treatment, and the contribution of DM accumulation post-anthesis to grain was ranked as D2, D6, D7>Wck, D3, D4>D5>D1>W0. Under the condition of W2, the DM accumulation in grain at maturity in D2 were the highest, followed by Wck, D3, D4, D5, D6 and D7, the lowest in D1 and W0 treatments. The DM accumulation in stems plus sheat, spikes axis plus glume and leaves in D2 were significantly higher than those in D1, D4, D5, D6 and D7, had no differ with Wck and D3 treatments. The DM accumulation post-anthesis and the contribution of DM accumulation post-anthesis to grain from D2 were significantly higher than the other treatment.In 2013~2014 wheat growing season, under the condition of W1, the DM accumulation in grain at maturity in D2 were significantly higher than those in Wck, D1, D3, D4, D5, D6 and D7, and the lowest in D1 and W0 treatments. The DM accumulation in stems plus sheath, spikes axis plus glume and leaves in Wck, D2, D3, D4 and D5 were significantly higher than those in D6 and D7, and the lowest in D1 and W0 treatments.The DM accumulation postanthesis from D2 was significantly higher than the other treatment, and the contribution of DM accumulation post-anthesis to grain in Wck, D2, D3, D4 and D5 were significantly higher than those in D1, D6 and D7 treatment. Under the condition of W2, the DM accumulation in grain at maturity in D2 treatment were the highest, the DM accumulation in stems plus sheat, spikes axis plus glume and leaves in D2 were significantly higher than those in D1 and W0, had no differ with Wck, D3, D4, D5, D6 and D7 treatments. The DM accumulation post-anthesis and the contribution of DM accumulation post-anthesis to grain from D2 were significantly higher than D1 and D7, had no differ with the other treatments.These results indicated that supplemental irrigation based on the soil moisture in the 0~40 cm soil layers had higher DM in grain than in irrigation with 60 mm treatment, promoted the dry matter accumulation post-anthesis and mobilized to grain, which was benefit for improving grain weight. 1.3 Effect of different treatments on nitrogen metabolism of winter wheatIn the two wheat growing seasons, the nitrogen accumulation in grain at maturity in D2 was the highest, followed by Wck and D3, the lowest in D1, D4, D5, D6 and D7 treatment. In 2012~2013 wheat growing seasons, Under the condition of W1 and W2, the nitrogen accumulation in stems plus sheath in D2 was significantly higher than those in W0, lower than D1, had no differ with Wck, D3, D4, D5, D6 and D7 treatments. The values in spikes axis plus glumes and leaves in D2 were higher than the other treatments. In 2013~2014 wheat growing seasons, Under the condition of W1, the nitrogen accumulation in stems plus sheath in D2 was lower than D1, had no differ with Wck, D3, D4, D5, D6 and D7 treatments. The values in spikes axis plus glumes and leaves in D2 had no differ with the other treatments. Under the condition of W2, the nitrogen accumulation in stems plus sheath in Wck and D2 was higher than those in D5, D6 and D7, had no differ with D3 and D4. There had no differentce of nitrogen accumulation in spikes axis plus glumes and leaves between treatments. These results indicated that supplemental irrigation based on the soil moisture in the 0~40 cm soil layers promoted the nitrogen accumulated into grain.In 2012~2013 wheat growing seasons, the nitrate content(NO3--N) in 60~180 cm soil layers in D2 was significantly lower than those in Wck, D3, D4, D5 and D6, which had no difference with D1. The total nitrogen content in 40~60 cm and 80~160 cm soil layers in D2 was the lowest. In 2013~2014 wheat growing seasons, the c NO3--N ontent in 60~180 cm soil layers in D2 was significantly lower than those in Wck, D3, D4, D5 and D6, and the total nitrogen content in 40~100 cm and 120~200 cm soil layers in D2 was the lowest. These results indicated that supplemental irrigation based on the soil moisture in the 0~40 cm soil layers promoted the use of nitrogen in 60~160 cm soil layers. 1.4 Effect of different treatments on senescence of flag leafIn 2012~2013 wheat growing seasons, the malondialdehyde(MDA) concentrations in flag leaves from D2 were lowest, but the superoxide dismutase(SOD) activities, catalase(CAT) activities and soluble protein concentrations in flag leaves from D2 were higher than those from Wck and D3 until 21 DAA, W0 had the lowest values. In 2013~2014 wheat growing seasons,, the MDA concentrations in flag leaves from D2 were lowest from 14 DAA to 28 DAA, the SOD activities, CAT activities and soluble protein concentrations in flag leaves were ranked as D2>Wck, D3>D1>W0. These results indicated that supplemental irrigation based on the soil moisture in the 0~40 cm soil layers could protect cells from oxidative damage during the mid or later stages of grain filling. 1.5 Effect of different treatments on root distribution and senescenceIn 2012~2013 wheat growing seasons, root length density and weight density in 40~60 cm soil layers from D2 were significantly higer than those in W0 and D1, and had no differ with Wck and D3 treatments. The root length density and weight density in 60~100 cm soil layers from D2 were the highest, followed by Wck and D3, lowest in D1 and W0 treatments. In 2013~2014 wheat growing seasons, root length density and weight density in 60~100 cm soil layers from D2 were significantly higer than those in the other treatments. These results indicated that supplemental irrigation based on the soil moisture in the 0~40 cm soil layers increased the root density in 60~100 cm soil layers, which was benefit for the use of water and nutrition of root in soil.The SOD activities and CAT activities in 20~60 cm soil layers from D2 were significantly higher than those from W0, had no differ with those in D1 and D3 at 10 DAA. From 20 to 30 DAA, the SOD, CAT activities and soluble protein concentrations in 40~60 cm soil layers from D2 were the highest, followed by D3, the lowest were from D1 treatment. The MDA concentrations from D2 were the lowest at the 20 and 30 DAA. These results indicated that supplemental irrigation based on the soil moisture in the 0~40 cm soil layers promoted the capacity of antioxidant of root in 40~60 cm soil layers at mid or later stages of grain filling.In thw two wheat growing seasons, the root activities in 0~60 cm soil layers from D2 were significantly higher than those from D1, had no differ with D3 treatment at 10 DAA. From 20 to 30 DAA, the root activities in 20~60 cm soil layers from D2 were the highest, followed by D3, the lowest were from D1 treatment. These results indicated that supplemental irrigation based on the soil moisture in the 0~40 cm soil layers promoted the root cactivities at mid or later stages of grain filling, which was benefit for the use of water and nutrition. 1.6 Effects of different treatments on grain yield and water use efficiency of winter wheatIn 2012~2013 wheat growing seasons, under the condition of W1, the grain yield in D2 was the highest, followed by Wck, D3, D4, D5, D6 and D7, the lowest in D1 tratment. The water use efficiency and irrigation water use efficiency in Wck and D2 were significantly higher than those in the other treatments. The irrigation water productivity in D2 was significantly higher than Wck, D3, D4, D5, D6 and D7, lower than that in D1 treatment. Under the condition of W2, the grain yield and water use efficiency in D2 were the highest, which had no differ with Wck, higher than those in D1, D3, D4, D5, D6 and D7, and the lowest in D1 tratment. The irrigation water use efficiency in D2 was significantly higher than those in the other treatments. The irrigation water productivity in D2 was the highest.In 2013~2014 wheat growing seasons, under the condition of W1, the grain yield, water use efficiency and irrigation water productivity in D2 was the highest, followed by Wck, D3, D4, D5, D6 and D7, the lowest in D1 tratment. The irrigation water use efficiency in D2 was significantly lower than that in D1, higher than that in the other treatments. Under the condition of W2, the grain yield and water use efficiency in D2 had no differ with Wck and D3, higher than those in D4, D5, D6 and D7, and the lowest in D1 tratment. The irrigation water use efficiency in D2 lower than that in D1, higher than that in the other treatments. These results indicated that supplemental irrigation based on the soil moisture in the 0~40 cm soil layers obtained a higher grain yield, water use efficiency and irrigation water use efficiency, which could be considered as the optimum treatment under this experiment conditions. 2 Effects of irrigation with micro-sprinkling hoses on water consumption characteristics and grain yield of wheat 2.1 Effects of irrigation with micro-sprinkling hoses on water consumption characteristics of wheatUnder the condition of micro-sprinkling irrigation applied at jointing and anthesis stages, the distribution uniformity of irrigation water in soil after irrigation at jointing and anthesis was increased by increasing sprinkling angle from 35°(T1) to 80°(T4), the differences in relative soil water content among the four inter-rows in T4 are not significant, and the CV is only 1.5% to 2.7% and 0.5% to 1.3% in the 0~20 cm and 0~140 cm soil horizons, respectively. Compared with T1 treatment, the irrigation amount decreased by 14.95 mm and 21.29 mm, and the total water consumption amount decreased by 34.41 mm and 37.92 mm, in 2010~2011 and 2011~2012 wheat growing season, respectively. Compared to T1, T2 and T3 treatments, the soil water consumption in 40~80 cm soil layer from jointing to anthesis and in 20~80 cm soil layer from anthesis to maturity in T4 treatment were highest, while the water consumption from jointing to anthesis. These results indicated that irrigation with a sprinkling angle of 80° could increase the water consumption in 40~80 cm soil layer from jointing to anthesis and in 20~80 cm soil layer from anthesis to maturity, decreased the soil water lose in the up layers and water absorb from the deep layers.The irrigation water distribution uniformity increased with the hose lengths decreasing from 80 m(W80) to 40 m(W40), The differences in relative soil water content among the four inter-rows in W80 are not significant, and the CV is only 1.5% to 2.7% and 0.5% to 1.3% in the 0 cm to 20 cm and 0 cm to 140 cm soil horizons, respectively. The soil water consumption amount, irrigation amount in anthesis and total irrigation amount, total water consumption amount of W40 treatment were significantly lower than those in W60 and W80 treatments. The soil water consumption amount in 40~60cm soil layer at jointing to anthesis and in 20~80cm soil layer at anthesis to maturity of W40 treatment were higher than those in W60 and W80 treatments. These results indicated that irrigation with sprinkling hose length of 40~60m could increase the water consumption in 40~60 cm soil layers from jointing to anthesis and in 20~80 cm soil layers from anthesis to maturity, decreased the soil water lose in the up layers and water absorb from the deep layers.2.2 Effects of irrigation with micro-sprinkling hoses on carbon metabolism of wheatThe Fv/Fm, ΦPSII, Pn and canopy apparent photosynthetic rate(CAP) in T3 and T4 are significantly higher than those in T1 and T2 at 10 DAA, from 20~30 DAA, the Fv/Fm, ΦPSII, Pn and CAP in T4 are significantly the highest, followed by that in T3, T2 and T1. Compared with T1, the Pn and CAP in T4 are higher by 52.4% and 36.5% at 20 DAA and 87.4% and 108.0% at 30 DAA, respectively. The total dry matter increased as the sprinkling angle increased from 35° to 80°. The total dry matter in T4 is higher by 9.0% than that in T1. Increasing the sprinkling angle from 35° to 80° increased the DM in stem + sheaths and grain. Moreover, the increase in grain count is significant, and thereby increased the ratio of the DM in grain to the TDM. The 1000-grain weight at maturity, duration of grain filling, and the mean value of grain filling rate increased as the sprinkling angle increases from 35° to 80°. These results indicated that irrigation with a sprinkling angle of 80°expended the duration of grain filling and increased the mean grain filling rate, thereby improved the dry matter accumulation in grain.The mean a ΦPSII of plants from the W40 and W60 treatments were significantly greater than that from the W80 treatment, but the Fv/Fm of plants from the W40, W60 and W80 treatments did not differ at 10 DAA. From 20~30 DAA, the mean ΦPSII and Fv/Fm of plants from the W40 and W60 treatments were significantly greater than those of plants from the W80 treatment. From 10 to 30 DAA, the mean Pn and CAP of plants from the W40 treatment did not differ from those of plants from the W60 treatment, but both Pn and CAP of plants from the W40 and W60 treatments were significantly greater than those of plants from the W80 treatment. The total dry matter accumulation above-ground decreased as the length of the micro-sprinkling hose delivering SI increased from 40 m to 80 m. The dry matter in grain, the dry matter in stem plus sheath, the dry matter in spike axis plus glume and the DM in leaves of plants from the W40 treatment were greater than those of plants from either the W60 or the W80 treatment. The duration of grain filling was significantly reduced as the length of the micro-sprinkling hose delivering SI was increased from 40 m to 80 m. These results indicated that irrigation with sprinkling hose length of 40~60m expended the duration of grain filling and increased the mean grain filling rate, thereby improved the dry matter accumulation in grain. 2.3 Effects of irrigation with micro-sprinkling hoses on grain yield and water use efficiency of wheatIn both 2010~2011 and 2011~2012 wheat growing seasons, the grain yield, water use efficiency, harvest index and soil water use efficiency in T4 treatment were the highest, with the mean values of 9178.7 kg hm-2, 22.7 kg hm-2 mm-1, 43.9% and 58.1 kg hm-2 mm-1, respectively. Compared with T1, the grain yield, water use efficiency, and harvest index in T4 are improved by 830 kg·hm-1, 4.0 kg·hm-2·mm-1, 1.0% in the 2010~2011 and 825 kg·hm-1, 3.6 kg·hm-2·mm-1, 2.4% in the 2011~2012 growing season, respectively. These results indicated that the most appropriate treatment for recommendation was the one which irrigated with sprinkling angle of 80° micro-sprinkling hose at jointing and anthesis stages.There were no significant differences in grain numbers per spike between treatments in either 2010~2011 or 2011~2012 wheat growing seasons, but the 1000-grain weight, grain yield and water use efficiency decreased significantly as the length of the micro-sprinkling hose delivering SI was increased from 40 m to 80 m. Number of spikes and harvest index did not differ between plants from the W40 and W60 treatments, but these were significantly greater in plants from the W40 and W60 treatments than in plants from the W80 treatment. However, the flow rate of SI in the W40 treatment(6.4 m3 h-1 in 2010~2011 and 6.0 m3 h-1 in 2011~2012, respectively) was less than that of the W80 treatment(6.8 m3 h-1 in 2010~2011 and 6.6 m3 h-1 in 2011~2012), which would decreased the irrigation efficiency(the effective irrigation area per unit time). The results indicated the optimum length of micro-sprinkling hoses for irrigating wheat after jointing was 40~60 m, which had higher uniformity of soil water distribution to improve photosynthetic capacity and promote wheat productivity. |
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