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.     

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.     

Growth and Yields of Cowpea (Vigna unguiculata (L.) Walp) as Influenced by Seed Characters, Soil Moisture and Season of Planting

Cowpea ( Vigna unguiculata L. Walp) is an important food legume grown under rainfed conditions in the tropics. However, the yield of this crop varies widely in most tropical ecosystems due to crop and environmental factors. Experiments were carried out to evaluate the effects of seed characteristics, soil moisture at planting and the season of crop establishment on growth and yield parameters of cowpea as these influence the productivity of the crop. Growth and yield of cowpea plants grown from small seeds with a high conductivity of their lea-chates were significantly lower than those grown from large seeds. Root growth of seedlings was most prominent under moderate soil moisture levels. Low soil moisture retarded root growth by reducing dry weights and suppressing the development of laterals. Shoot growth was more sensitive to increasing soil moisture stress than root growth. Planting cowpea in the wet season produced the highest yields. Within a season, growth and yield were higher when the crop was planted early. Establishment of the crop later in the season produced better quality seeds measured in terms of germination after controlled deterioration.     

Effect of Water Stress on Yield Components in Guar

This study was undertaken to measure the effect of water stress on yield and yield components in guar (Cyamopsis tetragonoloba [L.] Taub.) grown under water-stressed and water-optimal field conditions. Fifteen guar germplasms were grown in irrigated and dryland tests at Lubbock, TX on an Amarillo loam (fine-loamy, mixed thermic Aridic Paleustoll). Plants in each germplasm were hand harvested at maturity and data recorded for number of racemes/plant, pods/plant, seeds/pod, weight/100 seeds and g/seed/plant. We found differences among germplasms for yield components under both dryland and irrigated conditions. Germ-plasms responded statistically the same in both moisture levels. Among three pre-selected cultivars, water use efficiency did not differ statistically. Our analyses indicated that the component of yield most affected by water stress was number of pods/plant. Seed weight, seeds/pod, and racemes/plant each had progressively smaller effects on seed yield.     

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。     

Growth, Yield and Nodule Activity of Phaseolus vulgaris L. as Affected by Soil Moisture

A study evaluated the response of two varieties of beans ( Phaseolus vulgaris L.) to different soil moisture levels during a dry season. The soil moisture regimes maintained throughout the growth period were field capacity, 70–75 %, 50–55 % or 20–25 % available soil moisture.
Plant growth, yield and nodulation were optimal when plants grew at high soil moisture levels. With increasing stress, all measured parameters of both varieties were reduced. However, polebeans, with its vine type of growth was affected to a greater degree than bushbeans. In contrast, nodulation and nodule activity of both variables was affected by moisture stress.
A second experiment evaluated the effects of different soil moisture levels over the growth cycle of bushbeans, which produce greater yields under drier conditions. The highest yields were obtained at higher moisture levels throughout the growth cycle. Moisture stress up to flowering reduced yields to a greater extent than when the plants were subjected to reduced soil moisture after flowering appearance. Some casual mechanisms of the results of the experiments and possible implications for incorporating this popular vegetable legume in rainfed agricultural systems are presented.     

Influence of Soil Moisture and Fertilizer Potassium on the Vegetative Growth of Mungbean (Vigna radiata L. Wilczek) and Cowpea (Vigna unguiculata L. Walp)

Tropical food legumes are grown in a wide range of environments, and water stress is considered the principal environmental factor limiting growth and yield. Potassium fertilizer mitigates the impact of water stress in plants. However, the benefits of potassium in overcoming stress in tropical food legumes have not been investigated in comparative studies. The purpose of this study was to determine the benefits of potassium in overcoming water stress in mungbean and cowpea, two important tropical food legumes with different adaptabilities to soil moisture regimes. The experiment carried out under controlled conditions placed emphasis on vegetative growth and selected physiological parameters. The impact of potassium was different in the two legumes grown at optimal and suboptimal soil moisture. Potassium increased shoot growth of mungbean to a greater extent than in cowpea under suboptimal moisture conditions. The roots of cowpea showed a greater response to potassium fertilizer than in mungbean under suboptimal soil moisture. The plant water relations and photosynthetic rates of mungbean were improved to a greater extent by potassium under suboptimal soil moisture than those of cowpea. Although differences were observed in the responses of the vegetative growth of these species to moisture and potassium, in overall terms potassium promoted growth of both species when subject to suboptimal soil moisture. While field studies are required to validate the results, the application of potassium fertilizer can be considered a significant factor in overcoming soil moisture stress in these legumes commonly grown in tropical cropping systems.     

底墒差异对夏玉米生理特性及产量的影响

研究了底墒差异对夏玉米生理特性及产量的影响。试验结果表明,在夏玉米生育期间极度干旱的条件下,以冬小麦生育期间灌拔节水和抽穗水(各40mm),夏玉米生育期间灌两水(共计100mm)的处理夏玉米产量最高,达7466.58 kg/hm2。而且该处理的叶面积、光合速率、蒸腾速率等生理指标高于其余各处理,气孔阻力和叶温等生理指标则低于其余各处理,以上各生理指标的变化是由于前茬冬小麦不同生育期灌溉而造成的。本试验同时表明,研究作物的水分问题应与特定的种植制度相结合。     

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.     

Determination of Moisture Deficit and Heat Stress Tolerance in Corn Using Physiological Measurements and a Low‐Cost Microcontroller‐Based Monitoring System

In the southern United States, corn production encounters moisture deficit coupled with high‐temperature stress, particularly during the reproductive stage of the plant. In evaluating plants for environmental stress tolerance, it is important to monitor changes in their physical environment under natural conditions, especially when there are multiple stress factors, and integrate this information with their physiological responses. A low‐cost microcontroller‐based monitoring system was developed to automate measurement of canopy, soil and air temperatures, and soil moisture status in field plots. The purpose of this study was to examine how this system, in combination with physiological measurements, could assist in detecting differences among corn genotypes in response to moisture deficit and heat stress. Three commercial hybrids and two inbred germplasm lines were grown in the field under irrigated and non‐irrigated conditions. Leaf water potential, photosynthetic pigments, cell membrane thermostability (CMT) and maximum quantum efficiency of photosystem II (Fv/Fm) were determined on these genotypes under field and greenhouse conditions. Variations observed in air and soil temperatures, and soil moisture in plots of the individual corn genotypes helped explain their differences in canopy temperature (CT), and these variations were reflected in the physiological responses. One of the commercial hybrids, having the lowest CT and the highest CMT, was the most tolerant among the genotypes under moisture deficit and heat stress conditions. These results demonstrated that the low‐cost microcontroller‐based monitoring system, in combination with physiological measurements, was effective in evaluating corn genotypes for drought and heat stress tolerance.     

Moisture Stress Effects on the Yield and Water Use of Sorghum Hybrids and their Parents*

Little is known of the relationship between hybrids and parental material with respect to water use and drought resistance. Responses of sorghum (Sorghum bicolor [L.] Moench) F₁ hybrids to moisture deficits are partially determined by parental material. The yield and water use of six sorghum hybrids and their respective male and female parents were evaluated under stressed and well irrigated conditions during 1980 and 1981 at Tucson, Arizona. The soil was Comoro loamy sand (coarse-loamy, mixed, calcareous, thermic typic Torrifluvent) with an average available soil moisture of 16 % at field capacity. Changes in soil moisture were monitored semi-weekly by neutron modulation. Meteorological data were collected daily. The 1980 season had higher maximum temperatures and pan evaporation than the 1981 season. Differences in cumulative water use among entries were apparent within the same water treatments during 1981. Mean cumulative evapotranspiration (ET) for the stressed treatment was 248 and 281 mm for 1980 and 1981, respectively, and ET under well irrigated conditions was 419 and 528 mm for 1980 and 1981, respectively. Hybrids produced greater grain yield than their parents under both water treatments. This was due to greater seed number for hybrids. Seed numbers were more stable for hybrids over both treatments than for parents. Hybrids four and seven had the greatest grain yield in 1980 and 1981, respectively, under stressed conditions. Water use efficiency (WUE) was significantly different within water treatments but was not so between the irrigated and stressed treatments. Hybrids WUE was generally greater than that of parents except for hybrid five under irrigated conditions in 1981. Hybrids with WUE and stable yields were not necessarily reflective of parental material under stressed and non-stressed environments.     

Factors Associated with Reduced Yields of Delayed Plantings of Soybean1

Field experiments were conducted for four years (1981 to 1984) at Lexington, KY, USA (38° N latitude) to determine the causes of reduced yields associated with delayed plantings of soybean (Glycine max [L.] Merrill). Five cultivars were planted in mid-May and early July in row spacings ranging from 18 to 89 cm and the plots were irrigated to minimize moisture stress. Yields were significantly reduced by delayed planting because of reductions in the number of seed m^?2 and mass seed^?1. The yield reduction under irrigation indicates that moisture stress is not a major cause of reduced yields from delayed plantings. The reductions in seed number were associated with lower insolation interception during flowering and pod set and with smaller vegetative mass (g m^?2) at growth stage R5 (beginning seed fill). The data suggest that a vegetative mass at R5 greater than that required to intercept 90 % or more of incident insolation is required to maximize seed number. The length of the seed filling period was not affected by planting date. Mass seed^?1 was positively related to mean air temperature during seed filling, which suggests that the smaller seed from delayed plantings are a result of the lower temperatures associated with the later maturity.     

Growth Analysis Using Classical and Functional Techniques in Relation to Soil Moisture in Mustard

A Reid experiment was conducted to study the effect of soil moisture on growth of two mustard cultivars using classical and functional techniques of growth analysis. Two soil moisture levels were irrigated at 10-day intervals and a rainfed control was included. Total dry matter (TDM), leaf area index (LAI) and leaf area duration (LAD) were significantly increased by irrigation at most of stages of growth. Starting from a lower value, LAI and LAD reached a peak and then gradually declined. Among the growth attributes, crop growth rate (CGR), leaf area ratio (LAR) and leaf weight ratio (LWR) increased significantly under irrigation. Net assimilation rate (NAR) decreased more in the irrigated plants than the rainfed plants at the later stages of growth. LAR and LWR declined throughout with increasing time and plant weight. Seed yield of the irrigated plants was positively correlated with the pre-flowering LAI and the post-flowering CGR and NAR. In the rainfed plants, seed yield was positively correlated with LAI and CGR at the post-flowering stage and negatively with the post-flowering NAR and pre-flowering LAR.     

水分胁迫效应对冬小麦生长发育的影响研究

利用温室管栽试验，研究水分胁迫效应对冬小麦生长发育的影响。结果表明：苗期水分胁迫，拔节期与开花期复水能激发冬小麦根、茎、叶、冠生物量显著增长，三叶至分蘖期控水的处理绿叶面积日增量最大；前期一直干旱灌浆期复水能明显减缓植株的衰老速率。冬小麦前期经受中度或重度水分胁迫，拔节期复水后增产效果最大，前期经受中度水分胁迫，开花期复水后水分利用效率最高。确定土壤含水量占田间持水量55％为冬小麦分蘖期水分胁迫效应增产节水的水分临界指标。     

Effect of Spatial Soil Moisture Stress on Cotton Root Architecture

[Objective] This study aimed to explore the effects of spatial soil moisture stress on cotton root growth, and to analyze the corresponding changes in cotton root architecture. [Method] To produce soil moisture spatial stress, cotton spacing was set at 30 cm. The cotton was all irrigated on one side of the pole (the side sampling point). By excavating the cotton root, analysis of the main root bifurcation, which was cultivated away from the irrigation point, could be undertaken. [Result] The analyses of the cotton A (the nearest plant to the irrigation location) root system showed that soil moisture near the irrigation point was distributed uniformly. The root system architecture of the cotton cultivated near the irrigation point mostly presented a symmetrical "umbrella" pattern; the difference in root diameter between the main and lateral roots was 5–6 mm, and the average angle between them was 70°–80°, which decreased with the increase in cotton growth stage. Soil moisture spatial stress influenced the cotton plant C, which was cultivated away from the irrigation point, such that the root system architecture was asymmetrical. The roots of cotton plant C grew towards the high soil moisture zone; 48.15% of the lateral roots became thicker, which acted as a bifurcated main root. The difference in diameter between the bifurcated roots was 1–4 mm, and the average angle of the bifurcated roots along the vertical direction was between 20°–37°, which increased with the increase in cotton growth stage. [Conclusion] The results provide important information on the physiological responses of the cotton root system to the soil moisture environment.     

不同生育时期水分胁迫对花生生长发育和产量的影响

旨在明确花生水分敏感时期,为花生进行科学合理灌溉、提高产量提供理论依据和技术指导。以中早熟大果型‘豫花9326’和早熟小果型‘豫花9936’为材料,在全自动防雨干旱棚条件下,通过人工控水的方法研究了苗期、花针期、结荚期和成熟期干旱胁迫对花生营养生长、生殖生长、产量、水分利用效率等的影响。结果表明：不同生长发育时期干旱胁迫均导致花生生长发育受抑制、产量降低。其中花针期干旱,影响最大,花针期干旱主茎高、侧枝长分别降低了42.1%、37.5%,产量降低了22.2%。其次是结荚期干旱和苗期干旱,成熟期干旱影响最小。通过对各指标的分析,苗期干旱、花针期干旱主要是影响了单株结果数,从而降低了产量;结荚期干旱、成熟期干旱则是降低了饱果率、百仁重、出仁率,进而影响了产量。本研究明确了花针期是花生对水分胁迫最为敏感的时期,对提高花生水分利用效率和我国干旱半干旱地区花生单产具有重要意义。     

山西中北部春玉米生长季土壤水分动态及对产量的影响

为了掌握土壤水分与玉米生长发育内在关系,提高土壤水分利用率,统筹调配水资源和防灾减灾提供理论依据,利用1994—2010年山西省忻州市忻府区农业气象观测站春玉米生长季0~50 cm土壤水分和玉米产量观测资料,分析了玉米生长季土壤水分变化规律及对玉米产量的影响。结果表明：春玉米生长季土壤水分年际变化振荡明显,呈多波动变化,与年降水量相关显著;一年中土壤水分变化分为水分消耗期、水分补给期和水分平稳期3个阶段;土壤水分的垂直变化明显,在20~30 cm层含水量最大,0~20 cm为多变层,20~50 cm为缓变层,雨季土壤水分变化较干季复杂;玉米拔节—乳熟期土壤贮水量与气候产量呈正相关,抽雄期是需水临界期,此时0~50 cm土壤贮水量每增加10 mm,产量增加200~250 kg/hm²。     

关键生育期持续水分胁迫对春玉米土壤水分动态变化和产量的影响

为探讨关键生育期水分胁迫对春玉米土壤水分动态变化和产量的影响,在典型干旱区武威开展了关键生育期水分胁迫模拟试验,试验设置了CK(整个生育期供水充足的对照处理)、T1(拔节期持续干旱直至生育期结束)、T2(抽雄期持续干旱直至生育期结束)3种处理。结果表明,受水分胁迫影响,T1和T2干旱处理0—20cm和0—40cm土壤温度均高于CK处理,并且T2处理土壤温度高于T1处理；七叶期后,干旱处理剖面土壤含水量各层变化较大,至乳熟期,T1和T2处理土壤贮水量较CK分别减少了72%和57%；关键生育期的水分胁迫主要通过影响春玉米营养生长和生殖生长来影响最终的产量,T1和T2干旱处理产量分别减少了66.4%和54.2%,产量水平WUE分别减少了23.4%和13.1%。研究结果可为春玉米关键生育期干旱发生进行定量评估提供依据,为生态系统响应阈值的确定提供了思路。     

High-temperature Effects on Germination and Viability of Weed Seeds in Soil

The control of weeds by solar heating of the soil using transparent polyethylene (PE) sheets was studied in the field during the summers of 1994 and 1995. The maximum soil temperature under plastic cover at 5 cm depth averaged 53°C. At 5 cm soil depth, solarization increased temperature by about 9°C. In the non-solarized soils, such high-temperature days were fewer. A temperature of 55°C at 5 cm soil depths was recorded both in irrigated and non-irrigated mulched soils. However, mulched soil recorded 70% of the treatment period compared with 43% in unirrigated and mulched soils. Lower depths of 10 and 15 cm did not attain a temperature 55°C or 60°C on any day during the experimental period.
Solarization treatment with PE sheets significantly increased NO⁻₃—N and NH⁺₄—N in comparison with non-solarized plots. While uncovered plots showed significant increase in available phosphorus and marginally increased in potassium and electrical conductivity. Organic carbon content and pH did not vary under different treatments.
PE mulching for 30 days significantly reduced the number of weed seeds, specifically Avena fatua L. and Phalaris minor Retz., while Trianthema monogyna Linn, and Asphodelus tenuifolius Cav. were not affected much in comparison with the former. Melilotus indica (L.) All, was not at all affected by the solarization treatment studied. The solarization reduction index (SRI) was calculated for each weed species studied and it was concluded that weeds having a low SRI can be controlled more effectively than weeds with high SRI values. The heating effect from solarization decreased significantly with soil depth. The 30 days' soil solarization treatment in moist soil was more effective than the 10 and 20 days' heating treatment in moist and dry soils for weed control.     

土壤水分对冬小麦生长后期光能利用及水分利用效率的影响

通过控制不同土壤水分条件形成不同的小麦（Triticum aestivum L.）群体结构,测定了抽穗到成熟期间小麦冠层光合有效辐射（PAR）截获及垂直分布、干物质积累和产量。研究表明,不同处理小麦冠层对PAR的截获量差异较小（小于15.7%）,但冠层上部（60~80 cm）的PAR截获量和生长后期PAR转化效率差异明显（100.7%和63.7%）,与产量和光能利用效率变化一致,可见土壤水分是通过改变小麦群体内PAR垂直分布及PAR转化效率对作物产量和光能利用效率产生影响。抽穗到成熟期间维持小麦冠层上部PAR截获率在50%左右是实现高产的重要保证。随着土壤水分改善,冬小麦光能利用率和产量持续增加,但水分利用效率却先于二者提前降低,说明改善水分利用效率是提高华北地区农业气候资源利用效率的关键。在底墒充足的条件下,分别在拔节和挑旗期灌水60 mm可获得较高的光能和水分利用效率及经济产量