[Effects of bundled straw mulching on water consumption characteristics and grain yield of winter wheat in rain-fed semiarid region]. / ç§¸ç§†å¸¦çŠ¶è¦†ç›–å¯¹åŠå¹²æ—±é›¨å »åŒºå†¬å°éº¦è€—æ°´ç‰¹å¾å’Œäº§é‡çš„å½±å“.

To explore a new technique of planting wheat with high yield and efficiency by mulching technology in rain-fed semiarid regions in Northwest China, a two-year fixed-site trail was conducted during 2013-2015. There were five mulching modes: (1) three sowing rows by bundled straw mul-ching with alternating 30-cm-wide mulching belt and planting belt (SM1), (2) four sowing rows by bundled straw mulching with alternating 40-cm-wide mulching belt and planting belt with (SM2), (3) five sowing rows by bundled straw mulching with alternating 50-cm-wide mulching belt and planting belt (SM3), (4) whole plastic film mulching with dibbling (PMF), (5) bare field planting without any mulching (CK). We examined the effects of different mulching modes on water consumption, water use efficiency (WUE), and yield of winter wheat in rain-fed region in Northwest China. The results showed that bundled straw mulching significantly increased soil water storage. Soil water storage with bundled straw mulching was remarkably higher than that with the whole plastic mul-ching with SM1＞SM2＞SM3. Soil water storage at 0-200 cm soil layer in flowering period was increased by 15.4%-20.8%,11.2%-14.7%and 10.1%-14.5% respectively over that in the bare field. Bundled straw mulching significantly increased water consumption during the whole growing period while reduced water consumption from sowing and flowering periods. Further, it increased water consumption from flowering to maturity periods and the ratio of water consumption during this period to the total water consumption during the whole growing periods. The results showed that mulching could increase the consumption ratio of deep water storage from the soil layer below 120 cm. Compared with CK, PMF and SM significantly increased grain yield and water use efficiency by 11.9%-19.5%, 26.9%-27.1%, respectively, and increased water use efficiency by 9.8%-13.9%, 18.4%-22.0% respectively. In all, bundled straw mulching could reduce water consumption ratio in the early growing periods, improve moisture condition, increase grain yield and water use efficiency of winter wheat. Therefore, we concluded that bundled straw mulching is an environment-friendly cultivation technology suitable for the winter wheat in semi-arid region of the Loess Plateau in Northwest China.

Regulatory effects of bundled straw covering on winter wheat yield and soil thermal-moisture utilization in dryland.

Bundled straw covering (BSC), using corn whole straw for partial coverage planting, is a novel dryland cultivation technique. To examine the effects of BSC on the thermal-moisture status and winter wheat yield under typical arid and semiarid conditions in the Loess Plateau of Northwest China, soil temperature, soil water content and consumption, grain yield and water-use efficiency were compared for four treatments, including no-tillage with straw mulch (NTS), whole field plastic mulching with soil covering on the top of the plastic mulch and bunch-seeding (PFM), open field cultivation (CK) and BSC during three growing seasons from 2013 to 2016. The results showed that PFM significantly increased soil temperature of 5-20 cm depth before jointing stage, while the warming effect of BSC and NTS was mainly in the wintering period. The three kinds of coverage methods after jointing stage had significant cooling effects. Both BSC and PFM significantly improved soil water storage effect during the fallow period. BSC significantly elevated soil moisture in the depth of 0 to 200 cm in the whole growing season. The improvement of soil moisture by PFM and NTS mainly occurred before the heading stage, and soil moisture in PFM treatment gradually decreased after heading stage. BSC and PFM significantly increased water consumption in the whole growth period and increased that during the jointing stage to the flowering stage, and promoted the utilization of soil moisture below 120 cm. Compared with CK, BSC, NTS and PFM significantly increased the number of panicles per unit area and biomass at maturity. In those three treatments, grain yield was increased by 19%-52%, 14%-30% and 15%-60%, respectively, and the annual water use efficiency was increased by 19%-61%, 14%-31% and 15%-58%, respectively. BSC had the same potential for increasing yield and water use efficiency as PFM. Based on factors such as winter wheat yield, soil thermal-moisture utilization and annual water consumption, BSC is a high-yield and efficient cultivation method that is conducive to the sustainable development of dryland agriculture in Northwest China.

[Effect of straw belt-mulching on soil temperature and yield of winter wheat in rain-fed semiarid region.] / ç§¸ç§†å¸¦çŠ¶è¦†ç›–å¯¹åŠå¹²æ—±é›¨å »åŒºå†¬å°éº¦ç”°åœ°æ¸©å’Œäº§é‡çš„å½±å“.

To evaluate the effects of straw belt-covering on soil temperature and yield of winter wheat in rain-fed semiarid region in Northwest China, five mulching modes, including flat field planting without any mulching (CK), whole plastic film mulching (PM), straw mulching by 30 cm covering belt with an interval of 30 cm planting belt with three-row sowing (SM1), straw mulching by 40 cm covering belt with an interval of 40 cm planting belt with four-row sowing (SM2), and straw mulching by 50 cm covering belt with an interval of 50 cm planting belt with five-row sowing (SM3), were set by two-year fixed-site trails in 2013-2015. The results showed that soil temperature significantly varied among different growth stages and soil layers in all treatments. SM1, SM2 and SM3 significantly decreased soil temperature by 1.0-1.3 ℃, 0.7-0.9 ℃ and 0.7-1.1 ℃ in the 0-25 cm soil layer, respectively. The mulching had double effects with increasing and decreasing soil temperatures. The straw mulching significantly increased soil temperature in the duration of seedling to overwintering stage, but greatly decreased soil temperature in the duration of reviving to mature stage. The temperature-increasing effect of film mulching was stronger than that of straw mulching, which was opposite to the temperature-decreasing effect. Straw mulching significantly reduced in the effective accumulated temperature and the daily temperature variations during the whole growth stages. The effective accumulated temperature under straw mulching decreased by 3.4-33.5 ℃·d, and the soil temperature difference decreased by 0.6-2.0 ℃. During over-wintering stage, the straw mulching showed a higher average soil temperature (0.2-0.3 ℃) and negative accumulated temperature (0.4-17.0 ℃·d) than those under the CK. The straw mulching significantly increased grain yield by 11.9%-19.5%. The variations of spikes per unit area were the main factor responsible for yield difference. The findings indicated that that straw mulching method is suitable for winter wheat production in rain-fed region of Northwest China.

[Genetic analysis of accumulation and remobilization of water soluble carbohydrates regulated by drought in wheat RIL stem at grain-filling stage].

Recombinant inbred lines (RIL, Longjian 19 x Q9086, F8) and their parents were undertaken to study characteristics of quantitative genetics of water soluble carbohydrates (WSC) accumulation, remobilization and its contribution to grain mass in different main stem internodes at the grain-filling stage as well as the correlations among the target traits under the rainfed (DS) or well-watered (WW) condition. All of the target traits of RIL had wide variations under both water conditions. The variation coefficient ranged from 2.7% to 62.1% under the DS, and from 1.9% to 52.1% under the WW. The diversity index varied from 0.61 to 0.90 under the DS, and from 0.64 to 0.89 under the WW. All tested traits were significantly affected by the genotype, water condition, internode and growth stage. The growth stage exerted strong impacts on the WSC content. The water condition and internode greatly influenced the WSC remobilization rate. But, the WSC contribution rate to grain was jointly controlled by the genotype, water condition and internode. There were significantly positive correlations between the WSC contents at the early flowering and grain-filling stages, the WSC remobilization rate and its contribution rate to grain at pre-anthesis stage, with the higher correlation coefficients under the DS than under the WW. All traits showed low heri- tability under both water conditions (hB2 = 0.31-0.56 under the DS, 0.44-0.67 under the WW). The numbers of gene pairs controlling all traits ranged from 6 to 29 under the DS, and from 3 to 19 under the WW. It indicated that alleles responsible for all the target traits of RIL showed substantially transgressive segregation and greatlysignificant sensitivity to the water condition, confirming the characteristics of quantitative traits.

[Effects of source-sink regulation on water soluble carbohydrates of vegetative organs and thousand-grain mass of wheat under different water conditions].

Two winter wheat cultivars with different drought tolerance were selected to investigate the effects of source-sink regulation on the vegetative organs water soluble carbohydrates (WSC) content and 1000-grain mass (TGM) of wheat under drought stress (DS) and well watered (WW) conditions. Sink-cutting increased the WSC content of different vegetative organs significantly, and promoted the relative transportation of the WSC positively; while source-cutting caused opposite responses. The effects of source-sink regulation on the WSC content and its relative transportation amount (TA) and transportation rate (TR) were significantly higher under DS and sink-cutting than under WW and source-cutting, for drought-resistant cultivar (Longjian 19) than for drought-sensitive Q9086, and for peduncle internode and PedI than for penultimate internode and PenI. Under source-cutting, the superior organs of Longjian 19 in the TR of total WSC were sheath, PedI, and PenI, which also contributed to the fructan TR of the two cultivars, while those of Q9086 were the PenI and the third internode from top (ThiI). Source-cutting decreased the TGM of Longjian 19 and Q9086 significantly, with the decrement being 27.3% and 31.7% under DS and 25.3% and 12.1% under WW, respectively. The correlation coefficients of the WSC content and its TA and TR and the TGM were significantly higher under sink-cutting than under source-cutting, and also, under DS than under WW. There existed a higher correlation coefficient (r2 > 0.900) of the TGM and the total WSC and fructan contents in different vegetative organs. The vegetative organs with closer correlation between their WSC content and its TA and TR and the TGM were mainly sheath and PedI. Under DS, the traits associated with the total WSC content had a higher correlation with TGM; under WW, the traits associated with sucrose and glucan contents generally showed a higher correlation with TGM. It was suggested that the effects of source-sink regulation on the WSC content of vegetative organs and the TGM were significantly affected by soil water environment, wheat genotype, and vegetative organs location.

[Effects of mulching on soil moisture in a dryland winter wheat field, Northwest China].

This paper studied the effects of different mulching modes on the soil moisture in a semi-arid rainfed area of Loess Plateau, Northwest China. Seven treatments were installed, i. e., mulching plastic film in summer (T1), mulching plastic film in autumn (T2), mulching 5 cm long wheat straw in summer (T3), mulching whole wheat straw in summer (T4), mulching plastic film in summer plus wheat straw (T5), mulching used plastic film after harvest (T6), and un-mulching (CK). In T6, the soil moisture in different layers at different crop growth stages was all higher than that in CK. In the other five mulching treatments, the soil moisture in 0-90 cm layer before flowering stage was obviously higher, but that in 0-90 cm layer after flowering stage and in 90-200 cm layer during the whole growth season was lower than that of CK. The soil moisture in 0-200 cm layer in T6 during the whole growth period was significantly higher than that in CK, with a difference of 0.9%, but the soil moisture in 0-200 cm layer in other mulching treatments was lower. As compared with plastic film mulching, straw mulching increased the soil moisture in 0-200 cm layer. The soil moisture under mulching with used plastic film after harvest was higher than that under mulching with new plastic film. As compared to CK, the grain yield of winter wheat with plastic film mulching was increased by 20.3%-29.0%, and that With straw mulching was increased by 5.0%-16.7%. There was a significant positive correlation between the crop productivity and the soil water consumption during the growth period (r = 0.77*).

[Experiment precision and comprehensive environmental evaluation of regional wheat trials in rainfed regions of China].

Based on the grain yield data of regional trials with 233 winter- and spring wheat cultivars (lines) in rainfed farmlands at 82 locations in four subregions of China in 2003-2009, this paper studied the experiment precision (EP), variety comparison precision (VCP), and testing-site discrimination ability and representativeness of national regional trials, and comprehensively evaluated the trial environment. The results showed that in one-location-one-year experiments, the average coefficient of variation (CV) and the relative least significant difference (RLSD) were 6.1% and 10.5%, respectively, and in multi-location-one-year experiments, the CV was all within 8.2%, and the CV and RLSD were mostly well controlled, indicating that the trials had a high precision. The testing-site discrimination ability was the highest in the northwest spring wheat subregion, but showed less difference in the other subregions. The testing-site representativeness was the best in the northeast spring wheat subregion, and the worst in the northwest spring wheat subregion. On the basis of the comprehensive consideration of the testing-site discrimination ability and representativeness, and by using the parameters of the environmental comprehensive assessment (r(g)h) of GGE model, it was shown that the proportion of the ideal trial locations for wheat in our rainfed farmlands was only 32.4%. Among the wheat production regions, the proportions of the ideal trial locations were in the order of northwest spring wheat subregion (40.9%) > northeast spring wheat subregion (33.3%) > Huang-Huai winter wheat subregion (30.4%) > north winter wheat subregion

[Stomatal response of spring wheat and related affecting factors under different irrigation treatment].

Taking three spring wheat cultivars as test materials, a field experiment was conducted to study the effects of different irrigation treatments on the stomatal conductance of the cultivars during their growth period, with the relationships between the stomatal conductance and the environmental factors analyzed. On the basis of winter irrigation with 1800 m3 x hm(-2) of water, three irrigation treatments, i. e., irrigating three times (T1), two times (T2), and once (T3) during spring wheat growth period, were installed, with 1050 m3 x hm(-2) of irrigation water each time. All irrigation treatments had greater effects on the stomatal conductance, which was decreased with the decreasing times of irrigation, and varied with the cultivars. From jointing stage to florescence, the stomatal conductance in all treatments had the same variation trend, i. e., decreased after an initial increase, and reached the peak at heading stage. After florescence, difference occurred among the treatments. In treatment T1, the stomatal conductance of all test cultivars increased after an initial decrease; in treatment T2, the variation patterns of stomatal conductance differed with cultivars; while in treatment T3, the conductance of all cultivars decreased all along. Among the environmental factors, relative atmospheric humidity had the greatest effects on the stomatal conductance, and their correlation coefficient in treatments T2 and T3 reached significant (0.82) and very significant (0.92* *), respectively. The stomatal regulation mechanism of spring wheat adapting to water deficit in Hexi corridor was of feedback manner.

[Variation analysis on the grain yield and main agronomic traits of spring wheat in rainfed regions of China].

Based on the grain yield data of spring wheat from the 2002-2005 regional trials with 13 cultivars (lines) on the rainfed farmlands at 18 locations of China, and by using variance analysis and GGE (genotype main effect plus genotype-by-environment interaction) biplot, this paper studied the effects of genotype, environment, and genotype x environment interaction (GEI) on the yield variation of spring wheat and the yield stability of different cultivars (lines). Comparing with genotype and GEI, the environment had much more contribution on the yield variation, accounting for 87.5%-92.0% of the total. In the GEI items, genotype x location had the greatest effect, whereas genotype x year had the smallest one. The average yield of modern spring wheat genotypes across years and locations in China was 2550 kg x hm(-2). Among the three yield components, thousand kernel weight (TKW) had the least variation under environmental change. The main environment factors affecting the yield variation were annual accumulated temperature ( > or =10 degrees C), precipitation in growth season, mean air temperature, altitude, annual precipitation, and frost-free period. The grain yield had significant positive correlations with spike number per unit area (SPU) (r = 0.675**), TKW (r = 0.456**), and kernels per spike (KPS) (r = 0.581**), and the SPU, KPS and TKW also had positive correlations (r = 0.244-0.480**) with each other, implying that these three yield components might be increased or improved synchronously.