CO2浓度升高对小麦水分利用效率的影响研究综述

A held experiment was conducted during three winter seasons on West Bengal laterite soil to study the effect of irrigation and paddy straw mulch on water consumption. Water use efficiency and yield of wheat are reported. Both irrigation and mulch increased wheat yield significantly; there was also significant interaction between irrigation and straw mulch application: three irrigations combined with mulch resulted in 21.6 q ha‐1 wheat grain yield compared with 17.5 q ha‐1 for three irrigations without mulch. Mulch consistently increased irrigation response. Both irrigation and mulch increased water consumption and water use efficiency of the wheat crop. To compare the two irrigation treatments, irrigation at crown root initiation followed up by at flowering stage gave higher values of water use efficiency as well as higher grain yield than that of irrigation applied at panicle stage followed by at crown root initiation.

That there existed time and spatial variation for winter wheat water use efficiency (WUE) in different scales in irrigation area could be concluded by studying winter wheat WUE in small scale, middle scale and large scale in irrigation area in 2004~2006 in this paper. It indicated that winter wheat WUE were much more different in the small, the middle and the large scales in different years, which were 1.61kg/m3, 1.30kg/m3 and 0.88kg/m3, respectively. With up scaling, winter wheat WUE was declining in 2004, while increased firstly and then declined in 2005 ~2006.

Yield, water use and root distribution of wheat as affected by pre-sowing and post-sowing irrigation

Carbon isotope discrimination (-) has been shown to be negatively correlated with water use efficiency for wheat cultivars grown in the glasshouse. In the field this negative correlation has been confirmed for peanut but it has yet to be confirmed for wheat. Indeed, several field studies on wheat have shown positive (rather than negative) relationships between dry matter production and -. The aim of this study was to determine the relationship between - and water use efficiency for wheat grown in a dryland environment characterized by winterlspring-dominant rainfall and terminal drought. Eight genotypes chosen to give a range in - of c. 2.0x10-3 were grown on a red earth at Moombooldool in the Riverina region of New South Wales. Water use and above-ground dry matter (DM) were measured over the course of the season. Water use was partitioned into transpiration and soil evaporation and values of crop water use efficiency (WET) and transpiration efficiency ( WT) calculated. To account for the effect on WT of seasonal changes in the vapour pressure deficit of the air (D), crop coefficients (k) were derived by multiplying WT by the transpiration-weighted average daytime value of D for each genotype. During the preanthesis period, when there was little limitation of soil water supply on growth, there was a positive relationship between DM and -, as observed previously. The relationship between WET and - also had a positive (though non-significant) trend, but the relationship between k and - was negative, i.e. once the effects of variation in the ratio T/ET and seasonal changes in D were accounted for, the negative correlation between water use efficiency and - re-emerged. This apparent conflict between WET and k arose because genotypes with high - values developed their leaf area faster, with two important consequences. First, high - genotypes transpired more of their water supply during the winter when D was low and the exchange of water for CO2 more efficient. Second, transpiration made up a greater proportion of total water use by high - genotypes. The relationship between water use efficiency and - was further complicated as the crops depleted the soil water store after anthesis. During this period DM production tended to be greater in low - genotypes that had conserved soil water in the preanthesis period. However, DM production also remained high for two high - genotypes. The cause of this variation in post-anthesis growth among high - genotypes was not established.

Trade-offs between water-use related traits, yield components and mineral nutrition of wheat under Free-Air CO2 Enrichment (FACE)

Pot experiment laid out to study the effects of watering, nitrogen fertilization, and their interactions on the growth, dry matter production and water use efficiency of two cultivars(Egyptian Sakha94 cultivated in 2009/2010 season and Turkish Adana99 cultivated in 2010/2011 season) of wheat. The experiment laid out in randomized complete design. Cultivars were grown in pots at the greenhouse of the Faculty of Life and Environmental Science, Shimane University during 2009/2010 and 2010/2011 growing seasons. Two watering levels started after booting stage (well-watered and desiccated) and five nitrogen fertilization levels0.0, 0.24, 0.48, 0.72 and 0.96g pot (0.0, 75, 150, 225, 300kg N h) respectively, were designed. Our objective was to determine the effect of nitrogen (N) from ammonium sulfate split-applied at different rates before anthesis on water use efficiency under well-watered and desiccated conditions in the recent Egyptian cultivarSakha94 and Turkish Adana99 used in pots. The results showed that the leaf area, shoot dry matter production at anthesis, total dry matter production, number of spikelet’s spike, number of spikelet’s pot, number of spikes pot, spad value after sowing to anthesis time, consumptive use and water use efficiency of wheat increased with increasing level of nitrogen under well-watered conditions for both Conference Proceeding Full Paper Hafez et al.; IJPSS, Article no. IJPSS.2014.10.009 1303 cultivars, but the stomatal conductance and transpiration rate decreased under desiccated conditions. No significantly difference among N levels under desiccated conditions. It was considered that under our experimental condition applied 0.96 g N pot (300 kg N ha) led to significantly increase in WUE in both cultivars under irrigated and desiccated conditions. However, WUE was significantly higher in desiccated conditions than irrigated conditions in in Sakha94 than Adana99. May the primary cause of increased WUE, decreasing leaf chlorophyll concentration, photosynthesis rate and stomatal conductance (gs).

Field experiment was undertaken during the rabi seasons of 2015–16 and 2016–17 to study the effect of tillage and irrigation interaction on soil water dynamics, root growth, yield and water use efficiency (WUE) of wheat in a maize-wheat rotation in a sandy loam soil. The treatments comprised of three levels of tillage as main plot [Conventional tillage (CT), Deep tillage at the interval of two years (DT) and No tillage with maize residue @ 5 t ha−1 (NT)] and three levels of irrigation as sub-plot [I1: 1 irrigation (CRI), I2: 3 Irrigations (CRI, Tillering, Flowering) and I3: 5 Irrigations (CRI, Tillering, Jointing, Flowering, Milk)] were evaluated in a split plot design. Results showed that no tillage with residue (NT) treatment maintained higher soil moisture content in the surface layer (0–15 cm) than that of conventional tillage (CT) and deep tillage (DT) but in lower layers (45–120 cm), soil moisture content under DT was higher than that of NT and CT. Profile moisture storage at 0–120 cm soil depth was the highest under DT followed by NT and CT, respectively. In both the years, seasonal evapo-transpiration under DT was higher than that of CT, followed by NT. The root length density (RLD) under DT was significantly higher than that of NT and CT by 12.5 and 40.7 per cent, respectively at 0–15 cm soil depth. The RLD increased significantly with increasing irrigation level at 0–15 cm soil depth. Grain yield of wheat during high rainfall year (2016–17) was higher than that of low rainfall year (2015–16) by 39.2 per cent due to higher water availability, lower maximum air temperature and more bright sunshine hours received during that period. In both the years, there was no significant difference among tillage treatments with respect to grain yield of wheat but it increased significantly with irrigation. However, during the year 2015–16, there was no significant difference in the grain yield due to I2 and I3 whereas during the year 2016–17, there was no significant difference in the grain yield between I1 and I2 irrigation levels. There was no significant difference among tillage treatments with respect to WUE of wheat in year 2015–16 but during 2016–17, WUE of wheat under DT was significantly higher than NT. During the year 2015–16, WUE of wheat decreased with the increase in irrigation levels but during the year 2016–17, there was no significant difference among the irrigation treatments with respect to WUE of wheat.

Meta-analysis of no-tillage effect on wheat and maize water use efficiency in China

Determining water use efficiency of wheat and cotton: A meta-regression analysis

Water resource scarcity has been increasingly becoming a threat to wheat (Triticum aestivum L.) production in North China Plain. Thus, a water-saving irrigation strategy should be urgently developed. We conducted a 2-yr field experiment to examine the effects of supplemental irrigation (SI) on the photosynthetic characteristics and water use efficiency (WUE) of wheat. This study employed two SI strategies: A quota SI using 60 mm water at jointing and anthesis stages (W1) and soil moisture testing SI (W2), which brings the target relative soil water content of 0-40 cm soil layer to 70% field capacity at jointing and anthesis stages. A non-irrigated treatment (W0) was used as control. Results showed that W2 significantly improved the water uptake in 80-160 cm soil layer compared with W1. Moreover, flag leaf photosynthetic rate, stomatal conductance, and transpiration 14-28 d after anthesis were highest in W2 successively followed by W1 and W0, and the difference was significant. Dry matter (DM) at maturity, DM accumulation post-anthesis and its contribution ratio to grain were significantly higher in W2 than in the other treatments. 13CO2 labeling results indicated that W2 promoted δ13C-photosynthate accumulation in grain. In 2012-2013 growing season, the grain yield increased by 56.05% and 5.74% and WUE increased by 26.17% and 6.34% in W2 compared with those in W0 and W1, respectively. In 2013-2014 growing season, the grain yield increased by 41.82% and 5.90% and WUE increased by 28.24% and 13.03% in W2 compared with those in W0 and W1, respectively. Therefore, W2 is a high-yield and water-saving treatment.

Winter wheat monoculture is a predominant cropping system for agricultural production in dry areas. However, fallow management effects on soil water conservation and crop yield and water use have been inconsistent among studies. We selected 137 studies and performed a meta-analysis to test the effects of tillage and mulching during the fallow period on precipitation storage efficiency (PSE), soil water storage at wheat planting (SWSp), crop yield, evapotranspiration (ET), and water use efficiency (WUE). Compared to conventional tillage (CT), conservation tillage during fallow period overall increased PSE, SWSp and wheat yield by 31.0, 6.4, and 7.9%, respectively, but did not affect ET and WUE. No tillage (NT) had a better performance on soil water conservation during fallow period but a similar effect on wheat yield and WUE compared to reduced tillage (RT) and subsoil tillage (ST). Compared to no mulching, fallow mulching practices overall increased PSE by 19.4%, but had a non-significant impact on SWSp, wheat yield, and ET. Compared to straw mulching, film mulching, and stubble mulching during fallow period, cover cropping as a biological mulching decreased SWSp, wheat yield, and WUE significantly. Wheat WUE was improved by straw mulching but not affected by film mulching and stubble mulching. Strong interactions between tillage method and mulching practices were found for most variables. NT with fallow mulching or with no mulching exhibited a greater impact on soil water conservation during fallow period compared to other combinations. The effects of tillage and mulching during fallow period on soil water conservation and wheat yield and water use also varied with soil and climatic conditions. Overall, NT in combination with straw mulching significantly increased SWSp, PSE, wheat yield, and WUE and can be the best fallow management practice for winter wheat production in varying edaphic and climatic conditions.

Context: To revive the practice of planting legume green manure (GM) in the fallow period in rainfed agricultural areas, it is essential to demonstrate the benefits of this practice on the yields and water use efficiency (WUE) of subsequent crops, especially when integrating with optimized water and fertilizer management. Objectives: We conducted a field experiment to determine the positive effects of planting legume GM in the summer fallow on the yield, WUE, and nitrogen uptake efficiency (NupE) of subsequent winter wheat, which was grown with plastic film mulching and integrated fertilization in the Loess Plateau of China. Methods: A split-plot-designed experiment was arranged with two main treatments, namely (1) wheat planting followed by GM planting in the summer fallow (GM) and (2) conventional wheat monoculture followed by bare land summer fallow (BL), and three sub-treatments: (1) control treatment without any chemical fertilizer (Ct), (2) application of chemical N, P, and K as basal fertilizer (B), and (3) application of basal fertilizer plus wheat straw return (BS). Results: In the initial two years, even in a dry year, GM did not decrease the soil water content and storage (0–200 cm layer) during the subsequent winter wheat season, relative to BL. But in the third and fourth years, GM increased the grain yield of winter wheat by 3.2% and 3.8%, respectively. B and BS increased the grain yield of winter wheat by 14.4% and 22.2%, respectively, during the third experimental year, and by 12.7% and 19.4% during the fourth experimental year, primarily through increasing the population density of winter wheat. The increase in the grain yield contributed to a higher WUE of winter wheat. In the third year, GM increased the water consumption (WC) and WUE of wheat by 2.4% and 1.7%, respectively, though they were far lower than B (8.3% and 5.6%) and BS (10.4% and 10.7%). B and BS resulted in a higher yield and N nutrition than GM alone, but GM combined with B and BS resulted in the highest yield and N nutrition, thus greatly decreasing the NupE and increasing N productivity. Conclusions: Planting legume GM in the fallow can further increase the long-term yield, WUE, and N utilization of winter wheat when integrated with chemical fertilization and wheat straw return in rainfed agriculture. Implications: Our study yields new insights into the agronomic benefits of legume GM application in semi-arid or analogous rainfed agroecosystems and underscores the critical role of water conservation in ensuring dryland agricultural production, particularly in regions undergoing optimization of fertilization.

Water use and water-use efficiency of wheat and barley in relation to seeding dates, levels of irrigation and nitrogen fertilization

Global rising atmospheric CO2 concentration ([CO2]) and drought stress exert profound influences on crop growth and yield. The objective of the present study was to investigate the responses of leaf gas exchange and plant water use efficiency (WUE) of wheat (C3) and maize (C4) plants to progressive drought stress under ambient (a[CO2], 400 ppm) and elevated (e[CO2], 800 ppm) atmospheric CO2 concentrations. The fraction of transpirable soil water (FTSW) was used to evaluate soil water status in the pots. Under non-drought stress, e[CO2] increased the net photosynthetic rate (An) solely in wheat, and dry matter accumulation (DMA), whereas it decreased stomatal conductance (gs) and water consumption (WC), resulting in enhanced WUE by 27.82% for maize and 49.86% for wheat. After onset of progressive soil drying, maize plants in e[CO2] showed lower FTSW thresholds than wheat, at which e.g. gs (0.31 vs 0.40) and leaf relative water content (0.21 vs 0.43) starts to decrease, indicating e[CO2] conferred a greater drought resistance in maize. Under the combination of e[CO2] and drought stress, enhanced WUE was solely found in wheat, which is mainly associated with increased DMA and unaffected WC. These varied responses of leaf gas exchange and WUE between the two species to combined drought and e[CO2] suggest that specific water management strategies should be developed to optimize crop WUE for different species in a future drier and CO2-enriched environment.

Influence of boundary plantation of poplar ( Populusdeltoides M.) on soil–water use and water use efficiency of wheat