微喷灌模式下冬小麦产量和水分利用特性

为探讨华北地区微喷灌模式下冬小麦节水高产栽培适宜的灌溉制度,于2012-2013年(平水年)和2013-2014年度(枯水年),在同一块地观测了微喷灌和畦灌模式不同灌水处理对冬小麦群体变化、叶面积指数和籽粒产量,以及水分利用效率和耗水特性的影响。两种灌溉模式按不同灌水量和灌水次数设置6种组合处理,微喷灌的灌水量为60~180 mm,畦灌的灌水量为74~229 mm。2012-2013年度,微喷灌各处理小麦平均产量较畦灌增加5.6%,灌水量低于或等于90 mm时,微喷灌的产量显著高于畦灌;微喷灌模式下,灌水量120 mm时获得最高产量,但灌水量超过150 mm时,微喷灌模式产量显著低于畦灌模式。2013-2014年度,微喷灌模式平均产量较畦灌模式增加0.8%,灌水量150 mm时微喷灌模式的产量最高。千粒重和水分利用效率也表现为微喷灌模式高于畦灌模式,2012–2013年度分别增加5.1%和8.7%,2013–2014年度分别增加7.9%和10.7%。在本试验条件下,为获得冬小麦高产、高水分利用效率,建议微喷灌模式在平水年灌水量90~120 mm、耗水量325~355 mm,在枯水年灌水量105~150 mm、耗水量335~380 mm,每次灌水定额30~45 mm。微喷灌与畦灌相比,在同等产量水平下,平水年节水潜力为20~50 mm,枯水年为70~110 mm。     

Inter‐row Mulch Increase the Water Use Efficiency of Furrow‐Irrigated Maize in an Arid Environment

The effect inter‐row polyethylene mulch on the water use efficiency and crop productivity of furrow‐ and drip‐irrigated maize (Zea mays L.) was evaluated in a field study. In contrast to the traditional ‘on ridge’ mulching, the inter‐row polyethylene mulch was placed in such a way that it could be easily removed for reuse since the row of plants itself was not covered but the furrows were completely covered. Irrigation needs were computed by multiplying the cumulative Class A Pan evaporation between irrigations by a crop coefficient that changed through the growing season. Our results indicate that inter‐row mulching induced earliness under both irrigation treatments. Seventy five percent of canopy density was attained in the mulched treatments contrasting with 45–61 % in the non‐mulched treatments at 34 days after sowing. Throughout the growing period, shoot biomass was significantly higher for the mulched treatments that had as well higher root biomasses. The overall estimated evaporative losses from the non‐mulched treatments were between 37 % and 39 % of the total water applied. The whole gross canopy water use efficiency in the furrow and drip mulched treatments was 64 % and 45 % higher than in the respective non‐mulched treatments. These results indicate that inter‐row polyethylene mulch is an efficient technique by which soil evaporation is reduced and plant productivity increased.     

灌溉和种植模式对冬小麦播前土壤含水量的消耗及水分利用效率的影响

为探讨华北平原地区冬小麦节水栽培的生产措施,2004-2006年,以冬小麦品种8049为试验材料,在大田4种灌溉条件下,研究了等行距平作、宽窄行平作、沟播和垄作4种种植模式对播前土壤含水量消耗及冬小麦耗水量、产量和水分利用效率的影响。结果表明,与等行距平作相比,另3种模式增加了播前土壤含水量的消耗,其耗水量显著提高,尤以沟播模式30 cm以下播前土壤含水量的消耗最为明显。和等行距平作相比,在灌拔节水+抽穗水和灌拔节水+抽穗水+灌浆水条件下,沟播模式显著提高冬小麦产量;而垄作模式的产量没有显著提高。在灌拔节水或灌拔节水+抽穗水条件下,沟播种植模式的水分利用效率显著高于其他3种种植模式。在本试验条件下,沟播种植结合灌拔节水或灌拔节水+抽穗水是一种值得推广的节水种植模式。     

Management alternatives for improved durum wheat production under supplemental irrigation in Syria

In the Mediterranean zone, efforts to optimize combinations of supplemental irrigation (SI), improved varieties, nitrogen (N) and sowing dates aim to improve and stabilize cereal yields and maintain quality, especially for durum wheat. Thus, a 4 year field study (1992/1993 to 1995/1996) on a deep clay soil in northern Syria assessed the impact of SI (rain-fed, 1/3, 2/3 and full SI) combined with variable N application rates (0, 50, 100, 150 kg ha⁻¹) and sowing date (early, normal, late) for four improved durum wheat varieties adapted to rain-fed and irrigated conditions. As rainfall and evapotranspiration varied over the 4 years, the amount of SI water required also varied. Yields varied with the season, and the main factors, except variety, were significant. Delaying sowing from November to January reduced yields and response to both SI and N. With irrigation, crop responses were generally significant up to 100 N ha⁻¹, whereas the optimum response for rain-fed conditions occurred with 50 kg N ha⁻¹. Limited SI (1/3) significantly increased yields, but almost maximum yields were obtained by 2/3 of full SI. Water- and N-use efficiencies were greatly increased by SI, with little variation among varieties. However, irrigation and delayed sowing decreased grain protein levels, which were partially compensated for by added N. A similar effect was observed for kernel vitreousness. Models developed from the response data can facilitate the potential transfer of these findings. Thus, in most growing seasons, minimum irrigation during the winter growing season, combined with appropriate fertilization, can enhance wheat output and yet maintain grain quality.     

高产小麦耗水特性及干物质的积累与分配

在2005—2006年和2006—2007年小麦生长季降水量分别为128.0 mm和246.4 mm条件下, 采用不同灌水量处理, 研究了高产条件下冬小麦的耗水特性和小麦干物质的积累与分配。结果表明, 底水和拔节水分别灌溉60 mm处理(W2)在两个生长季获得了最高的籽粒产量, 2005—2006年生长季其水分利用效率和灌溉水的利用效率均显著高于其他灌水处理; 2006—2007年生长季, 其水分利用效率较高, 降水量、灌水量和土壤供水量分别占农田耗水量的47.32%、23.04%和29.64%; 与不灌水处理(W0)相比, 灌水处理显著提高开花后干物质的积累量和开花后干物质积累量对籽粒的贡献率, 以W2处理最高, 分别达8 241.59 kg hm-2和84.18%。灌水量过多显著减少光合产物向籽粒的分配, 使产量降低。随灌水量增加, 小麦全生育期耗水量显著增大, 灌水量占农田耗水量的比例增加, 降水量和土壤供水量占农田耗水量的比例均降低, 以土壤供水量所占比例降低最大。综合考虑小麦的籽粒产量和水分利用效率, 在本试验条件下, 以底水和拔节水各60 mm的灌溉量为最优。在小麦生长季降雨量为246.4 mm条件下, 仅灌60 mm底水亦可获得较高的籽粒产量, 其土壤供水量占农田耗水量的比例和灌溉水的利用效率高于底水和拔节水处理。     

耕作方式对小麦开花后旗叶水势与叶绿素荧光参数日变化和水分利用效率的影响

2007-2009年小麦生长季, 以高产小麦品种济麦22为试验材料, 利用测墒补灌技术确定灌水量, 研究高肥力条件下条旋耕、深松+条旋耕、旋耕、深松+旋耕和翻耕5种耕作方式对土壤含水量、小麦开花至成熟阶段耗水量及其水分来源、旗叶水势和叶绿素荧光参数日变化、籽粒产量和水分利用效率的影响。结果表明, 深松+条旋耕和深松+旋耕处理成熟期60~200 cm各土层的土壤含水量均低于其他处理, 表明深松促进了小麦对深层土壤贮水的吸收。深松+条旋耕处理开花至成熟阶段的土壤贮水消耗量及其占阶段耗水量的比例最高, 其降水量和灌水量占阶段耗水量的比例最低。深松+条旋耕处理在6:00~18:00的旗叶水势、8:00~14:00的旗叶最大光化学效率(F_v/F_m)和实际光化学效率(Φ_PSII)均高于条旋耕处理, 表明深松有利于小麦旗叶在灌浆中后期保持较高的生理活性, 深松+旋耕和旋耕处理间的规律与其一致。深松+条旋耕处理在2个生长季的籽粒产量分别为9 516.48和8 957.92 kg hm⁻², 与深松+旋耕处理无显著差异, 翻耕处理次之, 条旋耕和旋耕处理低于上述处理。深松+条旋耕处理的水分利用效率最高, 深松+旋耕处理次之, 条旋耕和旋耕处理低于翻耕处理。本试验条件下, 深松+条旋耕是兼顾高产节水高效的耕作方式。     

灌水量对小麦籽粒粉含量和相关酶活性及水分利用效率的影响

在2004-2005年和2005-2006年小麦生长季,设置不同的灌水时期和灌水量处理,研究了小麦籽粒产量、籽粒淀粉含量、淀粉合成相关酶活性和水分利用效率。结果表明,全生育期不灌水条件下,籽粒中的可溶性淀粉合酶(SSS)和淀粉粒结合态淀粉合酶(GBSS)活性在灌浆初期显著升高,在灌浆中后期显著降低,同时灌浆后期支链淀粉、直链淀粉和总淀粉含量亦显著降低。拔节期和开花期每次灌水60 mm有利于小麦在灌浆中后期保持较高的SSS和GBSS活性,提高灌浆后期籽粒中的支链淀粉、直链淀粉和总淀粉含量;灌水量进一步增加时,灌浆中后期的SSS活性显著降低,GBSS活性升高,灌浆后期的支链淀粉含量降低,直链淀粉含量升高。在两个生长季中拔节期和开花期每次灌水60 mm处理的土壤贮水消耗量较高,水分利用效率最高和籽粒产量较高。在此基础上增加灌水量时,开花至成熟阶段0~60 cm土层的土壤含水量显著升高,土壤贮水消耗量降低,籽粒产量无显著变化,水分利用效率和灌溉水利用效率降低。     

隔沟交替灌溉对棉花生长、产量和水分利用效率的调控效应

为了探讨旱区农业高效节水新途径,于2004—2006年在甘肃石羊河流域干旱荒漠绿洲区田间,研究了常规沟灌、固定隔沟灌溉、隔沟交替灌溉对棉花生长、产量和水分利用效率的调控效应,结果表明,隔沟交替灌溉对棉花株高抑制作用较明显,而对蕾铃等生殖生长的影响较小,该技术能够调整棉花营养生长与生殖生长的关系,有效控制作物生长冗余,调节光合产物在根冠间的比例和分配,优化根冠比;可以在保持相同光合速率水平下大大降低叶片蒸腾损失,提高叶片水分利用效率,使霜前花比例提高,产量水平的水分利用效率分别较常规沟灌和固定隔沟灌提高17.22%和18.59%。在西北旱区棉花上应用隔沟交替灌溉技术具有较大的节水增产潜力。     

Effect of rice straw biochar and irrigation on growth,dry matter yield and radiation-use efficiency of maize grown on an Acrisol in Ghana

In order to determine whether the current low productivity associated with rainfed cultivation on degraded soils in Ghana can be improved by biochar amendment and irrigation, field experiments with maize were conducted over two seasons in 2017 and 2018. Rice straw biochar at rates of 0 t/ha (B₀), 15 t/ha (B₁₅) and 30 t/ha (B₃₀) was combined with irrigation regimes of full irrigation (I₁₀₀), deficit irrigation (I₆₀) and no irrigation (I₀). The I₁₀₀ treatment was irrigated to field capacity every 3–4 days according to time domain reflectometry measurements while the I₆₀ treatment received 60% of the irrigation amount given to I₁₀₀ but with the same irrigation frequency. The I₀ treatment was not irrigated. In both seasons, the B₃₀ treatment recorded the highest total dry matter yield (TDMY), intercepted photosynthetically active radiation (IPAR) and radiation-use efficiency (RUE) and these were significantly (p ≤ .05) higher than B₀ except for RUE in 2017. Irrigation regimes did not significantly affect TDMY, IPAR and RUE in 2017 but compared to I₁₀₀, I₀ significantly reduced TDMY, IPAR and RUE in the relatively dryer 2018 season. Measured ratio vegetation indices differentiated biochar treatments earlier in the 2018 season than during 2017 and increase of leaf chlorophyll content indices with biochar rate in both seasons indicated that biochar amendment improved nitrogen uptake. Our study demonstrated that rice straw biochar is capable of increasing TDMY, IPAR and RUE of maize grown on degraded soils in Ghana. The study further showed that TDMY, IPAR and RUE of deficit irrigated maize for two seasons were similar to the counterpart fully irrigated maize and may be a viable water management option for farmers in Ghana to save irrigation water resources.     

Impact of Water Stress on Maize Grown Off-Season in a Subtropical Environment

During the last decade, the production of off‐season maize has increased in several regions of Brazil. Growing maize during this season, with sowing from January through April, imposes several climatic risks that can impact crop yield. This is mainly caused by the high variability of precipitation and the probability of frost during the reproduction phases. High production risks are also partially due to the use of cultivars that are not adapted to the local environmental conditions. The goal of this study was to evaluate crop growth and development and associated yield, yield components and water use efficiency (WUE) for maize hybrids with different maturity ratings grown off‐season in a subtropical environment under both rainfed and irrigated conditions. Three experiments were conducted in 2001 and 2002 in Piracicaba, state of São Paulo, Brazil with four hybrids of different maturity duration, AG9010 (very short season), DAS CO32 and Exceler (short season) and DKB 333B (normal season). Leaf area index (LAI), plant height and dry matter were measured approximately every 18 days. Under rainfed conditions, the soil water content in the deeper layers was reduced, suggesting that the extension of the roots into these layers was a response to soil water limitations. On average, WUE varied from 1.45 kg m⁻³ under rainfed conditions to 1.69 kg m⁻³ under irrigated conditions during 2001. The average yield varied from 4209 kg ha⁻¹ for the hybrids grown under rainfed conditions to 5594 kg ha⁻¹ under irrigated conditions during 2001. Yield reductions under rainfed conditions were affected by the genotype. For the hybrid DKB 333B with a normal maturity, yield was reduced by 25.6 % while the short maturity hybrid Exceler was the least impacted by soil water limitations with a yield reduction of only 8.4 %. To decrease the risk of yield loss, the application of supplemental irrigation should be considered by local farmers, provided that this practice is not restricted by either economic considerations or the availability of sufficient water resources.     

灌水量对小麦氮素吸收、分配、利用及产量与品质的影响

以济麦20和泰山23为试验材料, 在大田条件下研究了灌水量对小麦氮素吸收、分配、利用和籽粒产量与品质及耗水量、水分利用率的影响。2004—2005年生长季, 小麦生育期间降水量为196.10 mm, 两品种的氮素吸收效率、籽粒的氮素积累量和氮肥生产效率均为不灌水处理低于灌水处理, 但籽粒氮素分配比例和氮素利用效率表现为不灌水处理高于灌水处理。拔节期前, 两品种的氮素吸收强度灌水180 mm处理高于灌水240 mm和300 mm两处理, 拔节期后反之; 成熟期, 植株氮素积累量和氮素吸收效率在各灌水处理间无显著差异。济麦20籽粒的氮素积累量和分配比例、氮素利用效率和氮肥生产效率, 均以灌水240 mm处理高于灌水180 mm和300 mm处理; 灌水180 mm和240 mm处理的籽粒产量分别达8 701.23 kg hm^-2和9 159.30 kg hm^-2, 耗水量为469.29 mm和534.48 mm, 两处理间籽粒品质无显著差异, 且均优于灌水300 mm处理。泰山23籽粒中氮素积累量及分配比例、氮素利用效率、氮肥生产效率和籽粒品质, 在各灌水处理间无显著差异; 灌水180 mm和240 mm处理籽粒产量显著高于其他处理, 分别达9 682.65 kg hm^-2和9 698.55 kg hm^-2, 其耗水量分别为468.54 mm和532.35 mm。两品种的水分利用率均随灌水量增加而降低。在2006—2007年生长季, 小麦生育期间降水量为171.30 mm, 济麦20和泰山23均以灌水240 mm处理的籽粒产量和水分利用率最高, 其耗水量分别为490.88 mm和474.88 mm。综合考虑产量、品质、氮素利用效率、氮肥生产效率和水分利用率, 生产中济麦20生育期灌水量以180~240 mm为宜; 泰山23在降水量达196 mm条件下, 灌水量以180 mm为宜, 在降水量为170 mm条件下, 灌水量以240 mm为宜。     

推迟拔节水及其灌水量对小麦耗水量和耗水来源及农田蒸散量的影响

于2007-2008和2008-2009小麦生长季, 以高产中筋冬小麦品种济麦22为材料, 采用测墒补灌的方法, 研究推迟拔节水及不同灌水水平对冬小麦耗水量、耗水来源、单位土地面积上旗叶叶面积和蒸腾速率、株间蒸发量、籽粒产量及水分利用效率的影响。结果表明, 测墒补灌后0~140 cm土层能够达到目标含水量。相同补灌时期, 随补灌水平的提高, 拔节至开花阶段日耗水量增大, 0~120 cm土层贮水消耗量减小, 生育期总灌水量和田间耗水量增加, 土壤贮水消耗量先增加后减小, 土壤贮水消耗量和降水量占田间耗水量的比例降低。相同补灌水平, 由拔节期推迟至拔节后10 d补灌则麦田日耗水量减小, 挑旗期日耗水量增大, 拔节至开花阶段80~120 cm土层土壤贮水消耗量增加, 生育期总灌水量和田间耗水量亦增加, 降水量、灌水量和土壤贮水消耗量占田间耗水量的比例不变; 灌浆初期单位土地面积上旗叶叶面积和蒸腾速率降低, 株间蒸发量增加; 公顷穗数降低, 穗粒数、千粒重、籽粒产量、水分利用效率和灌水生产效率增加。本试验条件下, 在拔节后10 d补灌至0~140 cm土层平均土壤相对含水量为75%, 开花期补灌至70% (2007-2008年度)是兼顾节水、高产的最优处理。     

Yield and Seed Quality of Mungbean as Affected by Irrigation in a Dry Season

A field study was conducted with the objective of determining the effects of soil moisture on seed yield and quality of mungbean ( Vigna radiata L. Wilczek) when grown under rainfed and irrigated conditions in a dry season. Seed quality was determined in terms of germination and production of normal seedlings after controlled deterioration. The presence of adequate soil moisture increased growth and yields of mungbean significantly. The seeds from irrigated plots had a greater weight, owing to heavier cotyledons. Although germination of seeds from the irrigated plots was higher before and after controlled deterioration for 72 h, the number of abnormal seedlings was also greater. Controlled deterioration reduced germination of both categories of seed in the same manner. These factors indicate the low potential of using seeds produced under irrigation in dry seasons as planting material, especially after storage.     

不同灌溉方式对两个马铃薯品种生理特性和水分利用效率的影响

研究了两个抗旱性不同的马铃薯品种(荷兰15号和克新1号）在不同灌溉方式下的生长、生理特性和水分利用效率。结果表明, 不同灌溉方式对马铃薯生理指标有显著影响。隔沟交替灌溉区的植株株高和叶面积高于常规灌溉区和固定隔沟灌溉区。隔沟交替灌溉提高了干旱胁迫应答抗氧化酶过氧化物酶（POD）、超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的活性,而反映胁迫受害程度的丙二醛（MDA）浓度均低于常规灌溉和固定隔沟灌溉处理。在隔沟交替灌溉条件下,克新1号的产量比常规灌溉提高了3.84％,水分利用效率比对照提高了35%。荷兰15号的产量与常规灌溉没有显著差异,水分利用效率比对照提高了28%。由此得出,在马铃薯生产中应用隔沟交替灌溉技术具有较大的节水增产潜力,其中克新1号是水分利用效率高、抗旱性强的品种。     

不同底墒条件下补灌对冬小麦耗水特性、产量和水分利用效率的影响

我国黄淮平原水资源紧缺,而且年际间降水量及其时间分布存在较大差异,探明不同底墒条件下补充灌溉对冬小麦产量和水分利用效率的调节效应及其生理基础,可为该地区冬小麦节水高产栽培提供理论和技术支持。2013—2014和2014—2015年冬小麦生长季,在播种期0~100 cm土层土壤贮水量分别为201.5(A)、266.3(B)和317.0mm(C)3种底墒条件下,各设置4个补灌水处理,包括不灌水、拔节期+开花期补灌、越冬期+拔节期+开花期补灌、播种期+拔节期+开花期补灌,研究不同处理冬小麦耗水特性、旗叶光合、干物质积累与分配、产量及水分利用效率的差异。结果表明,冬小麦生育期总耗水量和土壤水消耗量均随播种期底墒的提高而增加。在底墒A和B条件下,冬小麦主要消耗降水和灌溉水。提高播种期补灌水平或于越冬期补灌,冬小麦在底墒A条件下对土壤水的消耗量显著增加,在底墒B条件下对土壤水的消耗量显著减少。在底墒C条件下,冬小麦耗水以土壤水为主,其次为降水,再次为灌溉水;播种期或越冬期补灌显著增加生育期总耗水量,对土壤水消耗量则无显著影响。于播种期、拔节期和开花期补灌,冬小麦在底墒A条件下可获得较高的籽粒产量,但水分利用效率较低;在底墒B条件下籽粒产量和水分利用效率均较高;在底墒C条件下,仅于拔节期和开花期补灌即可获得高产和高水分利用效率,播种期和越冬期无需补灌。综上所述,播前底墒是实施冬小麦合理补灌的重要依据。     

局部灌水条件下不同根区在作物吸水中的作用

采用分根装置,在均匀灌水、固定部分根区灌水和根系分区交替灌水3种方式下,分期测定玉米的耗水量、两个1/2根区及整个根区的土—根系统水分传导与土壤含水量,研究各个根区在作物水分吸收中的作用。结果表明,3种灌水方式下,玉米耗水量与全部根区和灌水区土-根系统水分传导间均存在密切的正相关关系。均匀灌水条件下,1/2根区水分传导约占全部根区水分传导的一半;固定灌水条件下,灌水区占全部根区水分传导的比例远大于非灌水区,与全部根区接近。交替灌水条件下,两个根区对全部根区水分传导的贡献呈交替变化,其非灌水区占全部根区水分传导的比例较之固定灌水明显增大。全部根区土-根系统水分传导与灌水区土壤含水量明显相关,灌水区土壤含水量决定了整株作物的水分吸收情况。交替灌水的非灌水区从土壤到根系仍有一定的水分传输作用,而固定灌水的非灌水区使全部根区的土—根系统水分传导降低。     

Reduction in soil loss from erosion-susceptible soils amended with humic substances from oxidized coal

Soils that pose high risk of erosion require amendment with either natural or synthetic soil conditioners to reduce soil loss hazards. The objective of this study was to evaluate the potential of using coal-derived humic substances (as soil conditioners) to reduce runoff erosion on erosion-susceptible soils. Surface (0–20 cm) samples of severely degraded soils from Principina in Tuscany (Orthic Xerofluvent) and Bovolone in Venice (Udic Ustochrept) in Italy were used to assess the effects of five rates (0, 0.05, 0.10, 0.50 and 1.00 g/kg) of humic acids (HA) on soil loss and other hydrological parameters. A rainfall simulator was used to apply approximately 40 mm/h intensity rain for 1 h on soil beds of dimensions 2 m × 0.5 m × 0.01 m, packed at a bulk density of 1.20 Mg/m³ and inclined at a slope of 15%. The amount of soil eroded (E) and the time to initiate runoff (Rt) and drainage (Dt) were related to changes in the water-holding capacity and aggregate stability of the soils following the HA treatments. In the control treatments, the values of E, Rt and Dt were higher in the Principina than Bovolone soil. Increasing HA rates generally delayed Rt, accelerated Dt and reduced E substantially on both soils. On the Principina soil a reduction of about 36% in soil loss was obtained by adding only 0.05 g/kg of HA (equivalent to 100 kg/ha). On the sandier Bovolone soil, the same magnitude of reduction was achieved with 0.10 g/kg (200 kg/ha) of HA. Improvements in Rt and Dt from the HA amendments explained between 58 and 81% of the variation in E from both soils. Furthermore, improvements in the water retention capacity more than in the aggregate stability of these soils accounted for the reduced runoff erosion. These results show that amending erosion-susceptible soils with low rates of coal-derived humic substances is a potentially effective soil management practice for reducing erosion rates.     

Cone index and root growth in surface and subsurface microirrigated hardpan soil

Restricted root growth caused by subsurface hardpans and low water holding capacity reduces crop yields in many United States southeastern Coastal Plain soils. With intensive irrigation it is possible to obtain suitable yields without deep tillage. The objective of this study was to find differences of root growth and cone indices between surface and subsurface applied sources of irrigation water. We measured root growth and cone index in intensively managed irrigation plots of green beans (Phaseolus vulgaris L.) in 1988 and 1989. Microirrigation tubes were placed on the surface or in the subsurface — buried at a depth of approximately 0.25 m — and irrigated either continuously or with intermittent pulses of water. Mean profile cone indices for the surface tube placement were significantly lower than for the subsurface tube placement. Mean profile cone indices for the continuous irrigation treatment were significant lower than for the intermittent irrigation treatment. However, no one treatment significantly reduced the cone indices within the hardpan. Total root count was significantly greater for the subsurface tube placement with increased root growth below the 0.1-m depth. There was a high density of roots next to the subsurface tube that would have been effective in uptake of water from the microirrigation tube. However, yield was significantly greater for the surface tube placement. For all treatments, the largest concentration of root growth occurred in the top 0.2 m of the soil within the row. We expected this for the surface irrigation treatment. However, we also measured this for the subsurface treatment, probably because of high rainfall and upwelling of water from the subsurface micro-irrigation tube.     

灌水对强筋小麦籽粒产量和蛋白质含量及其稳定性的影响

2005—2006年小麦生长季, 利用7个强筋品种, 按统一设计方案分别在7个省进行田间试验, 研究灌水在不同生态环境下对籽粒产量和蛋白质含量及其稳定性的调控效应。结果表明, 在小麦生育期平均降水量低于常年的情况下, 各试验点的平均产量以灌3次水(灌水时期分别为春2叶露尖、春5叶露尖和开花期,每次灌水量均为600 m³ hm^-2)的处理最高, 显著高于灌2次水(灌水时期为春5叶露尖和开花期, 每次灌水量均为600 m³ hm^-2)和灌1次水(灌水时期为春5叶露尖期, 灌水量为600 m³ hm^-2)的处理, 但与灌4次水(灌水时期分别为春2叶露尖、春5叶露尖、开花期和灌浆期,每次灌水量均为600 m³ hm^-2)的处理差异不显著。随着灌水次数和灌水量的增加, 各试验点总体呈现产量提高和试验点间差异缩小的趋势, 产量环境指数越低的试验点, 灌水处理的增产效果越好。说明灌水可使不同生态环境下强筋小麦产量的稳定性增强。平均产量越高的品种, 在各试验点间的产量变异越小, 即稳定性越好; 产量的环境指数越高, 品种间产量变异系数越小。不同灌水处理的籽粒蛋白质含量差异显著, 随灌水次数增加, 平均蛋白质含量有逐渐降低的趋势, 但在降水过少的河北任丘试验点, 增加灌水使蛋白质含量有所提高。同一品种在不同试验点的蛋白质含量有较大变化。在各试验点间变异系数小的品种, 其蛋白质含量静态稳定性较好; 而变异系数大的品种则对生态环境变化有较大反应, 说明其品质的栽培可塑性较强。     

Environmental impact of soil erosion under different cover and management systems

Runoff, soil loss and physical chemical composition of surface soil, runoff water and eroded sediment were measured for three erosive rainstorms of the 1988 Autumn-Winter season, on clay soil slopes (Typic Chromoxeret) under different cover and management systems in a locality of Sicily.Four years reconsolidated natural grass-sod (Avena fatua and Lolium tumulentum), natural grass-sod with implanted forage shrubs (Atriplex halimus) and natural grass-rod afforested with Pine trees (Pinus halepensis), reduced significantly runoff and soil loss in comparison with tilled fallow following four years durum wheat cultivation.While differences in runoff and soil loss between reconsolidated systems were not significant, the higher biomass yield (Stringi et al. 1991) and the better soil cover (Chisci et al. 1991) of the Atriplex system, increased O.M. content of the soil and prevented soil erosion under very intense rainstroms of the semiarid Mediterranean area.The comparison of textural and aggregate grain-size composition of surface soil and sediment confirmed that physico-mechanical composition of sediment detached and transported by over-land flow on clayey soils is better estimated by pseudo-textural grain-size composition of surface soil (Chisci et al. 1989) than from textural composition.Soil loss amounts, and O.M., N and P enrichment ratios, combined in a specifically devised Environmental Impact Index (EI), demonstrated the excellent environmental protection value of reconsolidation of arable soils. However, Pinus system was somewhat less efficient than Atriplex and good natural grass-sod systems.