生物可降解地膜对马铃薯生长及水分利用效率的影响

为研究旱作条件下生物降解地膜对马铃薯生长及水分利用效率的影响,以‘紫花白’作为试验材料,设置裸地(CK)、聚乙烯塑料地膜、生物可降解A膜、玉米秸秆、生物可降解B膜5种覆盖材料来研究生物可降解地膜对马铃薯耕层土壤温度、土壤含水量以及产量的影响。结果表明,与传统裸地(CK)相比,聚乙烯塑料地膜、生物可降解A膜、玉米秸秆、生物可降解B膜4种覆盖材料处理下耕层土壤(0~ 25 cm)日平均温度提高2.02、1.67、1.40、1.47℃;各覆盖材料均可提高土壤含水量,聚乙烯塑料地膜、生物可降解A膜、玉米秸秆、生物可降解B膜覆盖耕层土壤(0~25 cm)平均含水量提高3.12%、2.00%、1.92%、2.48%;各覆盖材料较对照马铃薯块茎产量增加6.25%、21.18%、17.07%、31.71%。试验结果表明,生物可降解地膜覆盖可以提高土层的温度、土壤含水率以及马铃薯产量,在不同覆盖方式中,生物可降解B膜覆盖效果最好。     

滴灌带间距和灌水定额对春小麦产量和水分利用效率的影响

为了探究春小麦合适的滴灌灌水定额和滴灌带间距组合,2015年3—7月进行了春小麦大田试验,研究3种滴灌带间距(D1：60 cm、D2：90 cm、D3：120 cm)和3种灌水定额(I1：35 mm、I2：45 mm、 I3：55 mm)对西北旱区春小麦产量和水分利用效率的影响。试验结果表明：产量最高的处理为D1I2达到8964 kg/hm²。当滴灌带间距为60 cm和90 cm时,灌水定额从35 mm增加至45 mm时产量显著增加,灌水定额达到55 mm时产量分别下降9.5%和2.2%。灌水定额为35 mm和45 mm时,滴灌带间距60 cm的处理产量显著高于滴灌带间距120 cm的处理;灌水定额增加到55 mm时,3个滴灌带间距处理产量无显著差异。水分利用效率在1.57~2.11 kg/m³间变化,最高的为D2I2处理。综合考虑产量、灌水量、水分利用效率和滴灌带投入,D2I2处理是该地区最优的滴灌带间距和灌水定额组合。     

Mulching Improves Water Productivity,Yield and Quality of Fine Rice under Water‐saving Rice Production Systems

Water‐saving rice production systems are inevitable in the wake of severe water shortage in rice‐growing regions of the world. Mulches can improve water productivity, yield and quality of rice through increase in water retention. Studies were conducted for two consecutive years to assess the potential role of mulches (plastic and straw) in improving the performance of water‐saving rice production systems in comparison with no mulch used and conventionally irrigated transplanted rice. Water‐saving rice production systems in this study comprise aerobic rice and transplanted rice with intermittent irrigation. These systems saved water (18–27 %) with improved water productivity more than the conventional system. However, these systems caused a yield penalty of 22–37 %; nevertheless, these yield losses were compensated with the application of mulches under water‐saving rice production systems. Both plastic and straw mulches were helpful in improving moisture retention and water productivity (0.18–0.25 kg grain m^?3 water) relative to non‐mulch treatments (0.19–0.29 kg grain m^?3 water). Mulch application was also helpful in reducing the number of non‐productive tillers and sterile spikelets, and improving the productive tillers, kernel number and size, and kernel quality. Plastic mulch was more effective than straw mulch in improving water retention, water productivity and reducing spikelet sterility. In conclusion, the mulching improved the soil moisture retention, and thus enhanced the rice water productivity, spikelet fertility, paddy yield and quality of rice. This signifies the importance of mulching in water‐saving rice production systems.     

Leaf Carbon Isotope Discrimination as an Accurate Indicator of Water‐Use Efficiency in Sunflower Genotypes Subjected to Five Stable Soil Water Contents

Leaf carbon isotope discrimination (CID) has been suggested as an indirect tool for breeding for water‐use efficiency (WUE) in various crops. This work focused on assessing phenotypic correlations between WUE and leaf CID and analysing genotypic variability in four sunflower genotypes grown in a greenhouse in pots with five different stable levels of soil water content (SWC). We measured WUE at whole plant and leaf (intrinsic) level. At whole plant level, WUE was derived from the ratio of total dry aerial biomass (BM) to cumulative water transpired (CWT). At leaf level, intrinsic WUE was calculated as the ratio of light‐saturated CO₂ assimilation to stomatal conductance (A/g_s) in younger expanded leaves. Significant differences among the four genotypes and the five SWCs were observed for whole plant and leaf WUE and CID. Strong negative correlations were observed between whole plant WUE and CID as well as between intrinsic WUE and CID with decreasing water availability. No relationships appeared between BM production and WUE or CID. Our results can help agronomists and breeders to evaluate sunflower lines with high WUE for adaptation to drought conditions and for reducing water consumption and crop water needs. Leaf CID appears to be a pertinent and valuable trait to select sunflower genotypes with high WUE.     

温室增温和灌溉量变化对棉花产量、 生物量及水分利用效率的影响

为了解气候变化对棉花生长的影响,在2011—2012 年,通过2 个温室进行增温和灌溉量变化的试验（一个温室用红外灯管增温,另一个不增温）,每个温室设田间灌溉量的0.7 倍、0.85 倍、1 倍、1.15 倍、1.3 倍5 个灌溉水平,研究增温和灌溉量对产量、生物量及水分利用效率的影响。结果表明,棉花生长季平均温度增加1~3.5℃有利于产量的增加,生长季、花期和铃期温度升高1℃,产量分别增加200.694、225.732、109.838 kg/hm2,而蕾期温度升高1℃却会降低产量162.814 kg/hm2。生长季和蕾期增温1℃会分别降低生物量1079.2、1179.8 kg/hm2,降低产量和干物质的水分利用效率3.4215、2.8098 kg/(hm2·mm)。灌溉倍数每增加1 倍,产量和生物量分别增加734.51、2242.3 kg/hm2。但增温会增加水分的消耗量,这对于处于干旱区的新疆来说是不利的。随着气候变暖,棉花耗水增大,产量增加。     

控制交替沟灌中灌水控制下限对玉米叶片水分利用效率的影响

控制交替沟灌是通过调节作物生理过程实现节水的一项新技术。试验结果表明,在控制交替沟灌条件下,叶片蒸腾速率随着土壤含水量的降低而下降,而叶片光合速率则在土壤含水量降到某一数值以前没有显著的变化,从而造成叶片水分利用效率在较轻的水分胁迫下会有一定程度的提高。从叶片水分利用效率的角度分析,控制交替沟灌的灌     

灌水量和种植密度的配置对干热河谷紫甘蓝生物量分配、产量及水分利用效率的影响

为了揭示灌水量和种植密度配置下干热河谷紫甘蓝(Brassica oleracea var.capitata rubra)产量形成机理,研究了不同灌水量5800 m3/hm2(I1)、4900 m3/hm2(I2)、4600 m3/hm2(I3)和不同种植密度79200株/hm2(D1)、52800株/hm2(D2)、3...     

Radiation‐Use Efficiency,Biomass Production,and Grain Yield in Two Maize Hybrids Differing in Drought Tolerance

Drought‐tolerant (DT) maize (Zea mays L.) hybrids have potential to increase yield under drought conditions. However, little information is known about the physiological determinations of yield in DT hybrids. Our objective was to assess radiation‐use efficiency (RUE), biomass production, and yield in two hybrids differing in drought tolerance. Field experiments were conducted in 2013 and 2014 with two hybrids, P1151HR (DT hybrid) and 33D49 (conventional hybrid) under well‐watered (I₁₀₀) and drought (I₅₀) conditions. I₁₀₀ and I₅₀ refer to 100 % and 50 % evapotranspiration requirement, respectively. On average, P1151HR yielded 11–27 % greater than 33D49 at I₁₀₀ and about 40 % greater at I₅₀, At I₁₀₀, greater yield in P1151HR was due to greater biomass at physiological maturity (BM_pm) resulting from greater post‐silking biomass accumulation (BM_post). At I₅₀, both hybrids had similar BM_pm but P1151HR showed a higher harvest index and greater BM_post. RUE differed significantly (P < 0.05) between the hybrids at I₁₀₀, but not at I₅₀. At I₁₀₀, the RUE values for P1151HR and 33D49 were 4.87 and 4.28 g MJ^?1 in 2013, and 3.71 and 3.48 g MJ^?1 in 2014. At I₅₀, the mean RUE was 3.89 g MJ^?1 in 2013 and 3.16 g MJ^?1 in 2014. Results indicate that BM_post is important for maintaining high yield in DT maize.     

分根交替灌水对棉花生长、光合与水分利用效率的影响

应用部分根区干燥(PRD)技术,研究分根交替灌水(APRI)、分根固定灌水(FPRI)与全根系均匀灌水(BPRI)对盆栽棉花的生长、光合和水分利用效率的影响。结果表明:APRI黎明前与正午的叶水势均明显高于FPRI,而与BPRI无显著差异。APRI在叶片水分状况未变化时,显著降低了气孔导度,在维持光合作用不变的情况下,减少蒸腾量,瞬时水分利用效率与FPRI和BPRI相比分别提高了35.86%和63.51%。APRI处理的棉株在干旱复水后由于补偿效应,叶片生长速率和总叶面积较同等灌水量的FPRI分别提高了67.42%和27.16%。同时,干湿交替刺激APRI处理棉株的吸收根生长,其干重是FPRI的1.39倍。分根交替灌水在节水50%条件下,比同水量固定灌水处理的水分利用效率显著提高。     

灌溉春玉米大喇叭口期光合特性及水分利用效率研究

为了寻求在气候变化过程中保持作物产量不断增长,提高作物水分利用效率的地面灌溉节水与生物节水综合配套技术。通过分期播种和不同灌溉方式对大田春玉米进行试验,采用LI-6400便携式光合仪测定了石羊河流域灌溉区环境因子和春玉米大喇叭口期叶片光合生理指标和水分利用效率,分析了不同播期和不同灌溉方式对春玉米光合参数和水分利用效率的影响。结果表明：滴灌、喷灌和漫灌3种灌溉方式中滴灌最有利于提高春玉米叶片的净光合速率（提高10%~21%）、气孔导度（提高33%~43%）和作物水分利用效率（提高12%~20%）。方差分析表明,不同播期对春玉米叶片净光合速率、气孔导度和水分利用效率影响较小,但第二播期的净光合速率较第一、三播期提高10%~20%、蒸腾速率提高20%~28%、气孔导度提高20%~28%。通过显著性相关分析,空气温度、大气CO2浓度和光合有效辐射是影响滴灌叶片光合参数的主要环境因子,相关系数达0.810~0.986(P<0.05)。光合有效辐射和大气CO2浓度是影响喷灌叶片光合参数的主要环境因子,相关系数达0.850~0.980(P<0.05)。空气湿度、温度和大气CO2浓度是影响漫灌光合参数和水分利用效率的主要环境因子,相关系数达0.969~0.989(P<0.05)。滴灌也是最适宜于干旱区的抗旱、节水、节肥和增产的灌溉方式,3个播期中第二播期（4月20日“谷雨”前后）是当地最适宜于地膜春玉米播种的时期。     

不同种植模式对河北低平原区域地下水平衡和水分经济利用效率等的影响

河北低平原区是全世界地下水超采的主要地区,同时又是中国主要的粮食主产区。不同的种植模式对水资源利用和粮食安全生产起着非常重要的作用。为了探清河北低平原区不同种植模式对区域地下水平衡及水分经济利用效率等方面的影响,以河北低平原区沧州市为研究区域,通过利用实验结果及统计数据,对该区主要存在的一年两作、一年一作和两年三作的12种不同种植模式下的耗水、产量及对地下水的影响等进行了分析。结果表明：冬小麦—夏玉米一年两作的传统种植模式2年的产量最高(30000 kg/hm²),需水量也最大,达到1683 mm,但效益和水分利用经济效益最低[2.61元/(mm·hm²)],并且对地下水的影响最大;棉花—冬小麦—夏玉米的两年三作模式经济效益和水分利用经济效率最高,分别为15750元/hm²和12.2元/(mm·hm²);一年一作的种植模式对地下水的影响最小。因此,从该区域农业水资源可持续发展和粮食安全角度考虑,应该发展棉花—冬小麦—夏玉米的两年三作种植模式。     

Diversity in daytime and night‐time transpiration dynamics in barley indicates adaptation to drought regimes across the Middle‐East

A challenge to breeding drought‐tolerant barley in the Middle‐East is that precipitation and evaporative demand patterns dictate opposite water use strategies (conservative vs. risk‐taking). To characterize these strategies, we examined high‐resolution, whole‐plant transpiration rate (TR) responses to increasing vapour pressure deficit (VPD) and nocturnal TR (TR_N) dynamics among 25 local barley genotypes, using a novel phenotyping system. These traits were specifically selected because they exist under modalities enabling the expression of both strategies. The genotypes were selected from locations spread across a large aridity gradient represented by temperature and precipitation data spanning 30 years. Here, we uncovered a substantial diversity in TR responses to VPD where slopes of the linear responses correlated negatively with local maximal temperatures, pointing to opposite drought tolerance strategies. Low canopy conductance (low slopes) was associated with higher aridity, likely to enable water‐saving, while higher conductance was associated with wetter areas, likely to enable a more aggressive water use to maximize physiological activity. TR_N was highly diverse and represented up to 15% of maximal daytime TR, pointing to the possibility of increasing water‐saving by reducing TR_N. Furthermore, we detected pre‐dawn variation in TR_N that negatively correlated with local precipitation, indicating that a tighter circadian control is associated with adaptation to drought, consistently with a circadian resonance mechanism. These findings indicate that canopy conductance and TR_N are potentially beneficial to design drought‐tolerant barley germplasm adapted to different drought regimes taking place in the Middle‐East.     

Effect of Irrigation Patterns on Accumulation and Distribution of Dry Matter,Yield and Water Use Efficiency of Cotton in Southern Hebei

[Objective] This study examines how irrigation patterns affect soil moisture, growth and yield of cotton in southern Hebei, China. The results are used to inform irrigation patterns and improve the water use efficiency of cotton. [Method] Using the Nongda 601 cotton variety, a field split plot experiment was conducted in 2016 and 2017. The main treatments were no film (NF) and mulching film (MF), with side treatments of border irrigation (W1, 600 m³·hm^-2), limited amount every-other furrow irrigation I (W2, 450 m³·hm^-2) and limited amount every-other furrow irrigation II (W3, 300 m³·hm^-2). Six treatments NFW1, NFW2, NFW3, MFW1, MFW2, and MFW3 were applied. The film-covered border irrigation represents the conventional cultivation mode of local cotton. Impacts were measured as dry matter mass, yield and water use efficiency. [Result] (1) Dry matter mass of MF was significantly higher than that of NF in 2016 and 2017. However, there was no significant difference in different irrigation treatments under MF. When compared with the dry matter mass of NFW1 in 2016, that of NFW2 and NFW3 were significantly lower: by 14.28% and 13.44%, respectively. In 2017, the dry matter quality of NFW2 significantly increased by 11.29% compared with that of NFW1, but NFW3 showed no significant difference. (2) Cotton yield and water use efficiency showed similar trends in both years. There was no significant difference in yield and water use efficiency for the different irrigation treatments under MF. Compared with NFW1, NFW2 and NFW3 significantly decreased by 10.21%–16.00% and 13.63%–18.84% in yield, respectively, whereas water use efficiency significantly decreased by 8.33%–13.80% and 9.72%–14.61%, respectively. Compared with MFW1, yield and water use efficiency of NFW1 decreased slightly, but not significantly. Compared with MFW2, yield and water use efficiency of NFW2 significantly decreased 12.96%–16.62% and 13.73%–16.51%, respectively. Compared with MFW3, yield and water use efficiency of NFW3 significantly decreased 15.04%–16.29% and 15.03%–16.31%, respectively. [Conclusion] In wet and normal precipitation years, the NFW1 treatment resulted in high cotton yield while preventing residual film pollution; MFW2 and MFW3 treatments also achieved high yields and improved water use efficiency when irrigation quantity was reduced.     

DROUGHT STRESS: Soil Water Availability Alters the Inter‐ and Intra‐Cultivar Competition of Three Spring Wheat Cultivars Bred in Different Eras

Competition for water generates a classic aspect of the tragedy of the commons, the ‘race for fish’, where crops must allocate more resource to acquisition of the limiting resource than is optimal for crop yield allocation. A pot experiment using a simple additive (target–neighbour) design was conducted to examine the above‐ground and below‐ground growth of three spring wheat (Triticum aestivum L.) cultivars when grown alone and in mixtures at three levels of water availability. The effects of competition and water availability were compared by observing patterns of growth, biomass allocation and below‐ground outcomes. Competitive interactions were investigated among cultivars ‘HST’, ‘GY602’ and ‘LC8275’, target plant of each cultivar grown without neighbouring plants are referred to herein as control plant and one target plant of each cultivar sown surrounded either by same or another cultivar as intra‐ or inter‐cultivar competition. Competitive ability was assessed as the response ratio (lnRR) between the target plant surrounded by six other plants and the target plant in isolation. Our results showed that the cultivar ‘HST’, released over a century ago, produced a higher biomass and grain yield than the more recently released cultivars ‘LC8275’ and ‘GY602’ when grown as isolated plants with sufficient water supply. However, competition for resources from neighbours led to target plant biomass and grain yield being significantly reduced relative to controls in all three cultivars, particularly in ‘HST’. When subjected to intra‐cultivar competition, the two recently released cultivars ‘LC8275’ and ‘GY602’ had higher grain yields and water use efficiency for grain than ‘HST’ in all three water regimes. The landrace ‘HST’ had better and significantly linear relationships between biomass and biomass allocation, root length and specific root length, whereas the recent and modern cultivars had much more water‐related species‐specific changes in root morphology and allocation patterns. These results suggest that crop traits that influence competitive ability, such as biomass allocation to roots and root plasticity in response to drought have changed in modern wheat cultivars because of breeding and selection.     

耕作方式与秸秆还田对冬小麦–夏玉米轮作系统中干物质生产和水分利用效率的影响

为探讨黄淮海地区一年两熟制下土壤耕作方式与秸秆还田相结合的适宜模式,2010—2012年进行了两年度的田间试验,研究不同处理对冬小麦–夏玉米轮作系统干物质生产和水分利用效率的影响。通过比较常规耕作+秸秆还田、常规耕作+无秸秆还田、深耕+秸秆还田、深耕+无秸秆还田、深松+秸秆还田、深松+无秸秆还田6个处理,发现深松(耕)与秸秆还田可以增加冬小麦和夏玉米的农田耗水量,降低休闲期农田耗水量,提高作物叶片相对含水量、净光合速率、蒸腾速率和茎秆伤流量,促进植株干物质积累,进而提高作物籽粒产量和水分利用效率。耕作方式与秸秆还田对冬小麦和夏玉米的干物质生产和水分利用效率存在显著交互作用。与常规耕作+无秸秆还田相比,深耕+秸秆还田和深松+秸秆还田处理的作物干物质积累量分别提高19.3%和22.9%,周年作物产量分别提高18.0%和19.3%,水分利用效率分别提高15.9%和15.1%,且两处理无显著差异。因此认为,与本试验相似环境条件下,宜在秸秆还田的基础上配合深松或深耕。     

西北黄土高原旱作区不同地膜覆盖种植模式谷田水温效应及水分利用效率研究

针对西北黄土高原旱作区年降水量不足、水资源分布不均及春季大风干旱等造成的谷子产量不高、水分利用率低等生产问题,设置裸地平作种植（CK）、PE膜全覆膜起垄穴播（T1）、渗水地膜半覆膜起垄穴播（T2）和PE膜半覆膜起垄穴播（T3）4个处理,研究不同地膜覆盖种植模式对谷田播种前和收获后0~100cm土壤含水量、不同生育期0~40cm土壤含水量、0~30cm土壤温度、谷子农艺性状、产量和水分利用效率的影响。结果表明,3种地膜覆盖模式均不同程度地改善了谷子生育期内土壤的水温状况,提高了谷子的群体水分利用率、产量及相关农艺性状。4种处理播种前和收获后0~100cm土壤含水量、不同生育期0~40cm土壤含水量、0~30cm土壤温度均为T1>T2>T3>CK。3种覆膜处理的单穗重、单穗粒重、千粒重和产量均显著高于CK处理,T1和T2处理与T3处理差异显著。T1、T3和T2处理的群体水分利用率分别较CK处理提高了7.55、1.05和1.65kg/(mm·hm²)。PE膜全覆膜起垄穴播模式可作为西北黄土高原区谷子生产的高产高效栽培技术模式。     

The Physiology and Stability of Leaf Carbon Isotope Discrimination as a Measure of Water‐Use Efficiency in Barley on the Canadian Prairies

Temporal and seasonal water deficit is one of the major factors limiting crop yield on the Canadian prairie. Selection for low carbon isotope discrimination (Δ¹³C) or high water‐use efficiency (WUE) can lead to improved yield in some environments. To understand better the physiology and WUE of barley under drought conditions on the Canadian prairie, 12 barley (Hordeum vulgare L.) genotypes with contrasting levels of leaf Δ¹³C were investigated for performance stability across locations and years in Alberta, Canada. Four of those genotypes (‘CDC Cowboy’, ‘Niobe’, ‘170011’ and ‘Kasota’) were also grown in the greenhouse under well‐watered and water‐deficit conditions to examine genotypic variations in leaf Δ¹³C, WUE, gas exchange parameters and specific leaf area (SLA). The water‐deficit treatment was imposed at the jointing stage for 10 days followed by re‐watering to pre‐deficit level. Genotypic ranking in leaf Δ¹³C was highly consistent, with ‘170011’, ‘CDC Cowboy’ and ‘W89001002003’ being the lowest and ‘Kasota’‘160049’ and ‘H93174006’ being the highest leaf Δ¹³C. Under field and greenhouse (well‐watered) conditions, leaf Δ¹³C was significantly correlated with stomatal conductance (g_s). Water deficit significantly increased WUE, with ‘CDC Cowboy’– a low leaf Δ¹³C genotype with significantly higher WUE and lower percentage decline in assimilation rate (A) and g_s than the other three genotypes (‘Niobe’, ‘170011’ and ‘Kasota’). We conclude that leaf Δ¹³C is a stable trait in the genotypes evaluated. Low leaf Δ¹³C of ‘CDC Cowboy’ was achieved by maintaining a high A and a low g_s, with comparable biomass and grain yield to genotypes showing a high g_s under field conditions; hence, selection for a low leaf Δ¹³C genotype such as ‘CDC Cowboy’ maybe important for maintaining productivity and yield stability under water‐limited conditions on the Canadian prairie.     

Seed Number and 100‐Seed Weight of Pearl Millet (Pennisetum glaucum L.) Respond Differently to Low Soil Moisture in Genotypes Contrasting for Drought Tolerance

Water stress after flowering, one of the major factors limiting yields of pearl millet, affects both seed setting and grain filling and is a consequence of more/less water used prior to anthesis. However, whether genotypes have different sensitivities for seed setting and filling under drought, if exposed to similar stress intensity, is unclear. Experiments were conducted in two pairs of pearl millet genotypes, that is, PRLT2/89‐33 and H77/833‐2, 863B and 841B, contrasting for terminal drought tolerance, and two genotypes, ICMR 01046 and ICMR 01029 (IL‐QTLs), introgressed with a terminal drought tolerance QTL from PRLT2/89‐33 into H77/833‐2. Total seed weight, panicle number, 100‐seed weight, seed number and stover biomass were measured at different soil moistures and throughout grain filling. Sensitive H77/833‐2 had higher seed number and yield under well‐watered (WW) conditions than in PRLT2/89‐33 and IL‐QTLs. Upon increases in water stress intensity, H77/833‐2 suffered losses mostly in stover biomass (45 %) and seed number (60 %) at 0.3 FTSW whereas the biomass and seed number of PRLT2/89‐33 decreased little (20 % and 25 %). The 100‐seed weight of H77/833‐2 decreased only 20 % under stress. Tolerant 863B also maintained a higher seed number and biomass under water stress than 841B. Grain filling duration in PRLT2/89‐33 and IL‐QTLs was similar to that of H77/833‐2 under WW conditions but lasted longer than in H77833‐2 under water stress (WS). Similarly, seed growth of 863B was longer than 841B under WS. It is concluded that the higher seed yield of tolerant parents PRLT2/89‐33 and 863B, and of IL‐QTLs under WS was explained by the retention of a higher number of seeds than in sensitive lines, while the decrease in the 100‐seed weight was proportionally less than the decrease in seed number. Phenotype with lesser number and larger size of panicles and larger grain size, like genotypes PRLT2/89‐33 and 863B, withstood post‐anthesis water stress better. IL‐QTL inherited part of these characteristics, indicating a role for the terminal drought QTL in maintaining larger seed number and higher 100‐seed weight. The continuous stover biomass increase under WW in H77/833‐2, due to tillering, might indicate that tiller growth and grains are in competition for resources after anthesis, and this may relate to the relatively shorter grain‐filling period.     

覆膜种植方式对旱作大豆生长发育、产量及水分利用效率的影响

针对甘肃东部旱作区年降水量少、季节分布不均及大豆生产春季干旱严重等问题造成大豆产量不高、水分利用率低等生产实际,以露地平播为对照,研究全膜覆盖沟播、半膜覆盖沟播、半膜覆盖平播、膜侧播种等4种不同覆膜种植方式对旱作大豆生长发育、产量和水分利用效率的影响.结果表明,全膜覆盖沟播使大豆提前出苗5天,生育期缩短12天,促进了大...     

Contrasting Water‐Use Efficiency (WUE) Responses of a Potato Mapping Population and Capability of Modified Ball‐Berry Model to Predict Stomatal Conductance and WUE Measured at Different Environmental Conditions

Potatoes (Solanum tuberosum L.) are drought‐sensitive and more efficient water use, while maintaining high yields is required. Here, water‐use efficiency (WUE) of a mapping population comprising 144 clones from a cross between 90‐HAF‐01 (Solanum tuberosum₁) and 90‐HAG‐15 (S. tuberosum₂ × S. sparsipilum) was measured on well‐watered plants under controlled‐environment conditions combining three levels of each of the factors: [CO₂], temperature, light, and relative humidity in growth chambers. The clones were grouped according to their photosynthetic WUE (pWUE) and whole‐plant WUE (wpWUE) during experiments in 2010. Two offspring groups according to pWUE and wpWUE were identified on the basis of experiments conducted in 2010, which in experiments in 2011 again showed significant differences in pWUE (46 %, P < 0.001) and wpWUE (34 %, P < 0.001). The high‐WUE group had a higher net photosynthesis rate (34 %) and dry matter accumulation (55 %, P < 0.001) rather than leaf‐level transpiration rate (?4 %, no significant difference) or whole‐plant water use (16 %). The pWUE correlated negatively to the ratio between leaf‐internal and leaf‐external [CO₂] (R² = ?0.86 in 2010 and R² = ?0.83 in 2011, P < 0.001). The leaf chlorophyll content was lower in the high‐WUE group indicating that the higher net photosynthesis rate was not due to higher leaf‐N status. Less negative value of carbon isotope discrimination (δ¹³C) in the high‐WUE group was only found in 2011. A modified Ball‐Berry model was fitted to measured stomatal conductance (g_s) under the systematically varied environmental conditions to identify parameter differences between the two groups, which could explain their contrasting WUE. Compared to the low‐WUE group, the high‐WUE group showed consistently lower values of the parameter m, which is inversely related to WUE. Differences related specifically to the dependence of g_s on humidity and net photosynthesis rate were only found in 2010. The lower ratio between leaf‐internal and leaf‐external [CO₂] and higher WUE of the high‐WUE group was consistent over a wide range of air vapour pressure deficits from 0.5 to 3.5 kPa. The mapping population was normally distributed with respect to WUE suggesting a multigenic nature of this trait. The WUE groups identified can be further employed for quantitative trait loci (QTL) analysis by use of gene expression studies or genome resequencing. The differences in population WUE indicate a genetic potential for improvement of this trait.