Effect of Scheduling Irrigation at Different Phenophases of Sweet Corn (Zea mays saccharata) and Delineation of Critical Stages Based on Stress Day Index

A field experiment was conducted during the summer of 1996 at the Main Research Station, University of Agricultural Sciences, Hebbal, Bangalore to study the effect of phenophased irrigation schedules on green cob and fodder yield and to delineate critical stages based on Stress Day Index. There were seven irrigation schedules consisting of a combination of two IW/CPE ratios (irrigation water/cumulative pan evaporation), viz. 0.6 and 0.8 shuffled at three growth stages: 10–35 DAS (days after sowing), 36–65 DAS and 66 days to harvest in RCBD (randomized complete block design) with four replications. The investigations revealed that all yield attributing characters such as cobs per plant, cob weight, green cob and fodder yields were significantly higher under the irrigation schedule of 0.8 IW/CPE ratio throughout the crop growth. The reduction in green cob and fodder yields were 39 and 25 % respectively, when irrigations were scheduled at 0.6 IW/CPE ratio throughout as compared to 0.8 IW/CPE. Also, frequent irrigation at 0.8 IW/CPE ratio throughout maintained higher plant relative water content (86.90 %) and higher available soil moisture (59.95–81.51 %) before irrigation as compared to delayed irrigations at 0.6 IW/CPE ratio. The quality parameter viz. sucrose content (2900 μg g−1) in developed seeds was also higher under frequently irrigated treatment. The stress day index indicated that vegetative followed by silking and tasseling were the critical stages for moisture stress.     

Performance of Sugarcane (Saccharum officinarum L.) Under Surface Drip, Sub Surface Drip (Biwall) and Furrow Methods of Irrigation

Field experiments were conducted at the Sugarcane Breeding Institute, Coimbatore, India during 1989–93 to study the productivity and water use efficiency of sugarcane under different methods of irrigation. The results showed that there could be a 44 % saving in water with higher water use efficiency in drip irrigation compared to conventional furrow irrigation. Among drip irrigation systems in the plant crop, sub surface drip (Biwall) at 40/140 cm spacing recorded a significantly higher number of millable canes, cane length and single cane weight compared to either conventional furrow irrigation or furrow irrigation based on IW/CPE (Irrigation Water Cumulative Pan Evaporation) ratio. In ratoon crop, Biwall irrigation at 60/120 cm gave significantly higher cane length and single cane weight compared to any other methods of irrigation. However, cane and sugar yields in Biwall irrigations were on par with conventional furrow irrigation but superior to either surface drip or furrow irrigation based in IW/CPE ratio.     

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。     

Influence of Soil Moisture on Growth, Water Use and Yield of Mustard

A field experiment was conducted to study the influence of soil moisture on growth, water use and yield of mustard ( Brassica juncea L. cv. Rai 5 ). Two soil moisture regimes were rainfed and irrigated at 10 days interval throughout the growing season. The total amount of water received as irrigation was 110 mm and as rainfall was 15 mm. Total dry matter per unit ground area, leaf area index (LAI), crop growth rate (CGR) and net assimilation rate (NAR) were increased and leaf area ratio (LAR) and specific leaf area (SLA) were decreased by irrigation. Chlorophyll content and relative leaf water content (RLWC) were increased by irrigation, but proline content was greater in the rainfed crop at both the flowering and pod-filling stages. Time taken to first flowering, duration of flowering, number of seeds/pod and harvest index were unaffected by irrigation. Plant height at harvest, number of pods/plant, seed yield and oil content of seeds were increased and 1000-seed weight was decreased by irrigation. The consumptive use of water increased with an increase in water supply, but the water use efficiency (WUE) was decreased.     

Photosynthetic Response of Wheat to Soil Water Deficits in the Tropics

The changes in photosynthetic rate and translocation of photosynthates in winter wheat (Triticum Aestivum L.) grown in lysimeters were studied, in response to periodic soil water deficit during late tillering and flowering stages. Soil water deficits were imposed to previously nonstressed plants during late tillering and flowering states. Timing of irrigation was scheduled according to the ratio between irrigation water applied and cumulative pan evaporation (IW/CPE) of 0.75 (low deficit), and 0.5 (moderate deficit), as well as by suspending irrigations after crown root initiation stage (severe deficit). To determine the rate of photosynthesis, a short radioactive pulse of ¹⁴CO₂ with 300 ppm concentration was given to second leaf from the top at tillering, and to the flag leaf at flowering stages for 20 second exposure time. The translocation of photosynthates was estimated by scanning ¹⁴C activity in different plant parts. In late tillering the midday Photosynthetic rate (PR) was significantly 3 mg CO₂ dm^?2 h^?1 lower under low water deficit (WD₁) than under zero water deficit (WD₀). Under higher stress conditions, soil water acted as a limiting factor to keep the rate from rising above 13.2 during stress at late tillering (WD₂), 14.5 flowering (WD₄), and 10.0 mg CO₂ dm^?2 h^?1 for stress at both the growth stages (WD₅), respectively. The difference in daily accumulated photosynthesis (8 h), between stressed and nonstressed were 15, 40, 42, and 77 mg CO₂ dm^?2 h^?1 respectively at WD₁ WD₂, WD₄, and WD₅. The retention of ¹⁴C in flag leaf decreased considerably after 24 hours of exposure time when the labelled assimilates were translocated in bulk to the ear head. Under stressed condition a general trend was observed for upward translocation of assimilates towards the ear, even from the stem and root. The percent ¹⁴C activity observed in ear after 24 hours was greatest in severely stressed plants. The photosynthetic rate is reasonable predicted by midday LDR and surface moisture.     

灌溉和施氮方式对甘肃陇中黄土高原春小麦产量和土壤含水量与有效氮含量的影响

旨在研究影响小麦产量的最佳灌溉与施氮方式组合。以‘定西42号’春小麦为材料,采用水氮互作的方法,设4种灌溉量（单位面积水深50 mm、100 mm、150 mm、200 mm）和3种施肥方式（拔节期施纯氮肥40 kg/hm ²、开花期施纯氮肥40 kg/hm ²、拔节期和开花期施纯氮肥40 kg/hm ²和50 kg/hm ²）。（1）灌溉量150 mm与开花期施氮肥40 kg/hm ²处理时,小麦产量都最高。（2）灌溉量150 mm时各个土层含水量最高,不同施氮处理,各个土层含水量高低顺序为分蘖期<开花期<拔节期。（3）小麦植株耗水量随灌溉量增加而增加、水分利用效率随灌溉量增加而减少。（4）分蘖期灌溉量150 mm时各个土层硝态氮含量最高;拔节期,0~10 cm土层铵态氮和硝态氮含量最高;开花期,灌溉量150 mm和追施纯氮肥40 kg/hm ²时各个土层硝态氮和铵态氮含量最高。灌溉量150 mm和开花期施纯氮肥40 kg/hm ²方式搭配,对甘肃陇中黄土高原春小麦产量、土壤有效氮含量和水分节约最有益。     

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。     

不同生育期干旱对南方春玉米生长发育及水分利用效率的影响

为了研究不同生育期干旱对南方春玉米的生长发育、土壤水分、产量及水分利用效率的影响,在防雨棚下的测坑中进行试验,设计了6个处理,春玉米需水关键期设计了3个水平,分析南方春玉米的生长发育、土壤水分、产量及水分利用效率规律。结果表明：拔节期轻旱对春玉米的株高和叶面积影响最大;灌浆期轻旱对春玉米的产量及产量性状影响最大;高水分处理的耗水总量最大,低水分处理的耗水总量最小;耗水量为464.6 mm时,最高产量为6795 kg/hm2;拔节期轻旱的水分利用效率最高。建议在南方春玉米不同生育期应采用适宜的灌水方式,可达到节水和高产的双重效果。     

基于无人机RGB遥感的甘蔗株高估测

为快速准确地估测甘蔗不同生育期株高，探讨了无人机RGB系统遥感估算株高的可行性及效果。利用无人机RGB遥感平台，获取苗期、分蘖期、伸长中、后期和工艺成熟期的影像，通过Pix4D mapper生成数字表面模型（digital surface model,DSM），采用Eris Arcmap提取株高，基于DSM提取的株高与实测株高建立各生育期的估测模型，采用决定系数（R2）、均方根误差（RMSE）和平均相对误差（MRE）对模型进行评价。结果表明，基于DSM提取甘蔗各生育期的株高高于实测株高；全生育期模型拟合性最好，预测精度较高（验证集R2、RMSE和MRE分别为0.9611、0.1623和0.1102），苗期株高模型预测精度最高。其他各生育期模型的拟合性不及全生育期和苗期，精度较低，工艺成熟期模型的预测精度最低，拟合性最差。因此，基于无人机RGB遥感平台获取甘蔗不同生育期影像后通过DSM提取株高并运用于甘蔗重要生育期株高的估测时，注意不同生育期模型的适用性。     

Effects of Irrigation at Different Growth Stages and Source-Sink Manipulations on Yield and Yield Components of Mung Bean, Vigna radiata (L.) Wilczek, in Dry and Intermediate Zones of Sri Lanka

Irrigation is a management option available to farmers in the subhumid zones of Sri Lanka to increase mung bean yields during the dry Yala season. The objective of this study was to quantify the yield gain in response to irrigation at different stages of the crop and thereby determine the most suitable stage/s of irrigation. Four field experiments were conducted during Yala in 1995 and 1996 at two sites, Maha-Illuppallama (MI) and Kundasale (KS). Eight irrigation regimes consisting of all possible combinations of irrigation at three growth stages of the crop were defined. The respective growth stages were vegetative (from germination to appearance of first flower), flowering (from appearance of first flower to 75 % pod initiation) and pod-filling (from 75 % pod initiation to maturity). The treatments which received irrigation during two or more stages had significantly higher yields (793–1396 kg ha⁻¹) than those which received irrigation during only one stage (401–756 kg ha⁻¹) with the lowest yield being shown by the rain-fed treatment (227–396 kg ha⁻¹). When at least two stages can be irrigated, irrigation during the flowering and pod-filling stages was most effective. Irrigation during flowering produced the highest yield gain when only one stage could be irrigated. Seed yield showed a strong positive correlation with number of pods m^−2. Fifity per cent de-podding caused yield reductions at both sites, indicating sink limitation. In contrast, 50 % defoliation reduced the yields only at MI where the number of pods m⁻² was greater than at KS. Hence, source limitation was present only when the number of pods was higher.     

膜下滴灌棉花关键生育期不同灌水量、灌水次数对其生长、产量及水分利用效率的影响

通过2004年棉花生长季田间试验,我们研究了膜下滴灌棉花关键生育期不同灌水量和灌水次数对其生长、产量及水分利用效率（WUE）的影响,旨在建立河北南部棉区滴灌条件下的优化灌溉模式,提高作物水分利用效率,达到节水增产目的。试验结果表明：不同灌水方式对棉花产量和水分利用效率的影响具有显著差异,棉花需水关键期花铃期分2次少量灌水处理,每次灌水量10．42mm,明显优于两次多量灌水和集中一次灌溉等其他处理,产量和WUE最高,分别高达4929．0kg／hm^2和0．98kg／m^3,具有明显的节水增产效益。     

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。     

Effects of water limitation on yield advantage and water use in wheat (Triticum aestivum L.)/maize (Zea mays L.) strip intercropping

Wheat (Triticum aestivum L.)/maize (Zea mays L.) strip intercropping is widely practiced in arid regions of northwestern China because of its high land use efficiency. However, its sustainability has been questioned because it consumes much more water than sole cropped wheat or maize. The present study was conducted to investigate the effects of water limitation on the yield advantage and water use of this system. Three field experiments were conducted in the Hetao Irrigation District in Inner Mongolia during the growing seasons of 2012–2014. Each experiment comprised two water applications, in which one was full irrigation and the other was a period of water limitation during the co-growth period of intercropping.The interspecific competition in wheat/maize intercropping was intensified by water stress. For water limitation applied during the wheat booting/maize V5 stage (Exp. I, second irrigation was not applied), the yield advantage of intercropped wheat (IW) over sole wheat was enhanced, whereas that of intercropped maize (IM) over sole maize was reduced compared with full irrigated treatments; for water limitation applied during the wheat jointing/maize V2 stage (Exp. II, first irrigation was not applied), the yield advantages of both IW and IM were greatly reduced; for water limitation applied during the wheat grain filling/maize V9 stage (Exp. III, third irrigation was not applied), the yield advantage of IW was slightly improved, whereas that of IM was reduced. The yield advantage of intercropping under limited irrigation was 25%, 3%, and 18% in Exps. I–III, respectively, whereas that under full irrigation ranged between 22 and 24%.Under well-watered conditions, wheat/maize intercropping used 24–29% more water than the weighted means of sole crops with the water use efficiency equivalent to sole crops. After the application of water limitation, 60 mm irrigation water was saved by intercropping every year, whereas the reduction of water use ranged from 25.1 to 70.8 mm; the changes in water use of intercropping relative to sole crops was reduced to 18–24%; the changes in water use efficiency stayed at nearly zero in Exps. I and III but decreased to a value of −13% in Exp. II. These results indicated that water limitation could be applied during wheat booting or filling stage in wheat/maize intercropping to save irrigation water in our study area.     

干湿交替灌溉耦合施氮对水稻根系性状及籽粒库活性的影响

以新稻20为材料进行土培试验,设置浅水层灌溉(0 kPa)、轻度水分胁迫(–20 kPa)和重度水分胁迫(–40 kPa) 3种灌溉方式及0氮(0N, 0 kg hm-2)、中氮(MN, 240 kg hm-2)和高氮(HN, 360 kg hm-2) 3种氮水平,研究不同水氮耦合处理对水稻根长、根冠比、根系伤流、根系有机酸含量、根系玉米素及玉米素核苷与籽粒酶活性的影响。结果表明,灌溉方式与施氮量存在显著的互作效应,轻度水分胁迫增加了主要生育期根长、根系伤流量、根系分泌物中有机酸总量、根系玉米素及玉米素核苷含量,提高籽粒ATP酶、蔗糖合酶及腺苷二磷酸葡萄糖焦磷酸化酶活性,降低穗分化后水稻根冠比,且与MN耦合后产量最高,为本试验最佳的水氮耦合运筹模式;重度水分胁迫则显著降低主要生育期根长、根系伤流量、根系分泌物中有机酸总量、根系玉米素及玉米素核苷含量,降低籽粒ATP酶、蔗糖合酶及腺苷二磷酸葡萄糖焦磷酸化酶活性,增加主要生育期根冠比。水稻籽粒产量与主要生育期水稻根长、根系伤流量、根系分泌物中有机酸总量、根系玉米素及玉米素核苷含量均呈显著或极显著的正相关,而穗分化至成熟期根冠比与水稻产量呈负相关;同时水稻根长、根系伤流量、根系分泌物中有机酸总量、根系玉米素及玉米素核苷含量与籽粒ATP酶、蔗糖合酶及腺苷二磷酸葡萄糖焦磷酸化酶活性呈显著或极显著的正相关。表明通过适宜的肥水调控发挥水氮耦合效应,可以创造良好的根系形态、提高水稻根系代谢能力和籽粒库的生理活性,促进水稻高产。     

Effect of Moderate Drought in the Early Stage on Cotton Yield,Fiber Quality and Water Use Efficiency

[Objective] A 2-year field experiment was conducted to determine the effect of a moderate drought regime in the early-stage on cotton yield, fiber quality and water use efficiency. [Method] An experiment was set up in 2015 and 2016 on the Qingyuan Experimental Plot of Hebei Agricultural University based on a split plot design with two main plots: (1) conventional irrigation (W1) and (2) drought (limited irrigation before sowing with no irrigation during the growing period, W2). Three sub-plots with different cotton cultivars were established: CCRI 50 (early maturity), Nongdamian 601 (ND 601, moderate earliness), and Jimian 958 (JM 958, intermediate maturity). [Result] (1) Drought stress affected the ratio of seasonal bolls. Under drought stress, the ratio of summer bolls decreased and that of autumn bolls increased. Because the precipitation peak in 2016 was higher than normal and mainly concentrated in July, which was later than in 2015, the ratio of autumn bolls increased in 2016. (2) Drought stress affected cotton yield but had no significant effect on fiber quality. Under moderate drought, the boll number per plant and boll weight of ND 601 and JM 958 decreased, the ratio of boll setting increased (P < 0.05), the boll weight of CCRI 50 increased, and the yields of all three cultivars decreased. Because CCRI 50 is an early-maturing cultivar and sensitive to water, its yield decreased significantly (41.0%). (3) Reducing irrigation by an appropriate amount was able to improve water use efficiency. The water use efficiencies of ND 601 and JM 958 averagely increased significantly, by 15.75% and 10.05%, respectively, between 2015 and 2016 under drought stress. The water use efficiency of CCRI 50 decreased significantly, by 15.9%, because of its early maturity and sensitivity to water stress. [Conclusion] Moderate irrigation has a significant effect on yield, fiber quality, and water use efficiency. Cotton yield losses caused by water stress can be ameliorated by making the best use of natural precipitation and by increasing planting density.     

不同冬小麦品种的离体叶片失水速率差异及对供水的反应

较低的离体叶片失水速率(RWL)与抗旱性有关已经得到很多研究者的认同.选取8个冬小麦品种为试材,设置干旱(0水)、节水(2水)和足水(4水)的水分条件,研究不同冬小麦品种对供水条件的反应和生育时期的RWL变化特征.结果表明:不同品种间的RWL差异不显著.RWL随着灌水次数的增加而增高.0水处理的衡7228 RWL最低,冀5579和石麦16也较低.2水处理的石麦16最低,石麦14和冀5579也较低.4水处理下,石新618 的RWL最低,石麦14和衡7228较低,综合3种灌水结果,石麦16、冀5579和石麦14抗旱节水性较好.RWL随着生育进程而变化,拔节期较低,逐渐增加,至抽穗期达到峰值,此后明显下降,直至成熟.前期控水对降低小麦离体叶片失水速率,提高抗旱节水性有利.     

灌水时期和灌水量对小麦耗水特性和旗叶光合作用及产量的影响

在2004—2005和2005—2006小麦生长季,以济麦20、泰山23和泰山22为试验材料,研究了不灌水(W0)、拔节水60 mm (W1)、拔节水60 mm+开花水60 mm (W2)和拔节水60 mm+开花水60 mm+灌浆水60 mm (W3) 4个灌水处理条件下小麦耗水特性、旗叶光合作用和产量变化。结果表明,2004—2005生长季,济麦20和泰山23均以W2处理籽粒产量最高,耗水量和灌水效率分别高于和低于W1处理;两品种的水分利用效率均以W1和W2处理高于其他处理,其中济麦20的W1和W2处理无显著差异,而泰山23的W1处理高于W2处理。2005—2006生长季,济麦20和泰山22分别以W1和W2处理获得最高籽粒产量,两处理的耗水量(451.3 mm和459.2 mm)无显著差异;两品种的水分利用效率均以W0处理最高,W3处理最低,其中济麦20的W1处理高于W2处理,而泰山22在两处理间无显著差异。随灌水量的增加,土壤供水量和降水量占总耗水量的百分率降低,灌水量占总耗水量的百分率增大。济麦20的W0处理的旗叶光合速率和磷酸蔗糖合成酶活性在灌浆初期与W1和W2和W3处理无显著差异,灌浆中后期显著降低,但W0处理有利于蔗糖向籽粒转移,灌浆后期旗叶中蔗糖滞留较少,这是W0处理的粒重显著高于其他处理的生理原因之一。综合考虑籽粒产量、水分利用效率和灌水效率,在未灌底墒水条件下,济麦20和泰山23以拔节水灌60 mm或拔节水和开花水各灌60 mm为节水高产的模式;在灌底墒水60 mm条件下,济麦20以拔节水灌60 mm、泰山22以拔节水灌60 mm或拔节水和开花水各灌60 mm为节水高产的模式。     

分蘖和乳熟期控制灌溉对水稻生长和产量的影响

为了合理的制定水稻控灌灌溉制度,开展了单生育期内水分控制灌溉对水稻生长影响的试验研究。在水稻分蘖(FN)和乳熟期(RS)分别以土壤饱和含水量的80%(FN1,RS1)和90%(FN2,RS2)作为灌溉下限进行控制灌溉。结果表明：与常规浅湿灌溉相比,生育期水分控制灌溉可以减少该生育期内灌水次数和灌水量,控制灌溉停止后,分蘖期处理水稻需水出现补偿效应,乳熟期则不明显;控制灌溉不利于水稻株高生长,有利于增加每穗粒数和每穗实粒数,对千粒重影响不明显;控制灌溉节水效应显著,但同时减产作用也十分明显,FN1、FN2、RS1和RS2处理分别节水21.1%,16.2%,29.4%和18.1%,减产27.8%,26.8%,29.5%和19.2%;分蘖期控制灌溉减产作用大于节水作用,灌溉水利用效率(IWUE)显著下降,较对照处理降低8.5%~12.7%,乳熟期控制灌溉IWUE和对照差异不显著。因此,从生产角度来讲,当灌溉水水资源匮乏需要控制灌溉时,为了提高IWUE,宜在乳熟期适当控灌,而分蘖期不宜控制灌溉。     

成熟期控水对烤烟生长及产量的影响

成熟期是烤烟需水次临界期。为明确烤烟成熟期土壤水分对烟株生长及烟叶产量的影响,试验在烤烟成熟期进行土壤控水,研究烟株物质积累及烟叶产量的变化。结果表明：成熟期土壤长期干旱不利于烟叶生长,干旱后复水对烟叶生长无明显影响,且土壤水分对烤烟茎围和根系体积的影响均不显著;长期干旱不利于烤烟根、茎和叶等器官生物量提高,旱后增加复水量有利于根系生长;长期干旱显著降低烟株干物质积累,复水提高干物质积累量,但仍低于充分灌溉处理;长期干旱烟叶产量降低9.70%,旱后复水2次烟叶产量仅降低1.80%,且上中等烟叶比例比对照处理（相对土壤含水率70%~75%）提高2.88%,而单位面积产值仅减少1.09%。烤烟成熟期干旱胁迫后复水一定程度限制了烟株生长,但烟叶产量下降较少,上中等烟叶比重提高,单位面积产值略微降低。     

Development of an irrigation regime for winter wheat to save water resources by avoiding irrigation at anthesis stage

Latest published information is limited on agronomic responses of winter wheat to irrigation quantity and the necessity of irrigation at the anthesis stage. This study was conducted to (1) evaluate winter wheat yield, water use, assimilate redistribution and economic benefit with respect to water input and (2) quantify relationship between water input and yield to develop a standard for withholding irrigation at anthesis. A 4-year long field experiment was conducted to evaluate winter wheat water use, yield formation pathway and farmers' income under three irrigation regimes: rainfed, irrigation at sowing and jointing (SJ-W) and irrigation at sowing, jointing and anthesis (SJA-W). The yield formation pathway was correlated with the water-induced variation in assimilate redistribution and accumulation. Throughout the experimental period, wheat yield was 19–38% lower in rainfed than that under other irrigation treatments. Moreover, SJ-W treatment substantially increased biomass accumulation at anthesis, accelerated assimilate redistribution in vegetative organs and eventually resulted in a similar wheat yield to that of SJA-W. Simultaneously, the SJ-W treatment had lower irrigation water, reduced additional irrigation cost, suppressed yield loss and obtained a similar farmer's net income to the SJA-W treatment. Water-induced variations in yield were determined by irrigation, rainfall and soil water storage. SJ-W plots receiving 204–331 mm water input (rainfall + irrigation) before anthesis and holding 549–587 mm soil water during anthesis stage achieved higher irrigation water use efficiency and yield relative to the rainfed and SJA-W plots. In contrast, water input under rainfed plots exceeded 200 mm before anthesis, limiting yield substantially even when seasonal soil water consumption exceeded 160 mm. Developing a standard for withholding irrigation at the anthesis stage should incorporate 204–331 mm of water input (rainfall + irrigation) before anthesis and 549–587 mm soil water storage at anthesis, which could achieve a high wheat yield and save water resources.