Deficit irrigation in maize for reducing agricultural water use in a Mediterranean environment

Research on crop response to deficit irrigation is important to reduce agricultural water use in areas where water is a limited resource. Two field experiments were conducted on a loam soil in northeast Spain to characterize the response of maize (Zea mays L.) to deficit irrigation under surface irrigation. The growing season was divided into three phases: vegetative, flowering and grain filling. The irrigation treatments consisted of all possible combinations of full irrigation or limited irrigation in the three phases. Limited irrigation was applied by increasing the interval between irrigations. Soil water status, crop growth, above-ground biomass, yield and its components were measured. Results showed that flowering was the most sensitive stage to water deficit, with reductions in biomass, yield and harvest index. Average grain yield of treatments with deficit irrigation around flowering (691 g m⁻²) was significantly lower than that of the well-irrigated treatments (1069 g m⁽²). Yield reduction was mainly due to a lower number of grains per square metre. Deficit irrigation or higher interval between irrigations during the grain filling phase did not significantly affect crop growth and yield. It was possible to maintain relatively high yields in maize if small water deficits caused by increasing the interval between irrigations were limited to periods other than the flowering stage. Irrigation water use efficiency (IWUE) was higher in treatments fully irrigated around flowering.     

灌水与覆膜对春玉米生长及水分利用效率的影响

在移动式遮雨棚内采用子母桶栽土培法,研究了充分灌水和调亏灌水2种灌水模式以及拔节期揭膜、抽雄期揭膜和全生育期覆膜3种覆膜时长对春玉米生长、产量和水分利用效率的影响。结果表明,覆膜可促进春玉米早期生长,而对后期生长不利。抽雄期是春玉米需水关键期,阶段蒸散模数达41.4%~47.2%。受前期亏水锻炼,调亏灌水复水后产生补偿效应,可有效协调植株根冠比并延缓衰老。与充分灌水相比,调亏灌水处理的总蒸散量减少4.3%~7.1%,水分利用效率提高1.9%~6.7%。抽雄期揭膜处理前期(覆膜时)增温保墒,后期(揭膜后)降温透气,与拔节期揭膜处理和全生育期覆膜处理相比,其相对产量和水分利用效率分别提高19.0%~23.3%和23.2%~26.0%。综合考虑产量、水分利用和环境因素,调亏灌水+抽雄期揭膜具有较好的节水、增产和环保效应,是适宜的春玉米灌水覆膜模式。     

Yield and water relations of wheat as influenced by irrigation and depth of tillage

Summary Development of a ploughpan has been reported in Bangladesh for almost all ploughed soils which are puddled for transplanted rice cultivation. Field information on the water requirement of dryland crops such as wheat and the effects of loosening the dense layer on crop yield and water use efficiency are very limited. Field experiments were, therefore, conducted in the grey floodplain soil of Sonatala series (Aeric Haplaquept) to study the irrigation and tillage effects on the yield and water relations of wheat (Triticum aestivum L. cv. Sonalika). The split plot design experiment comprised four irrigation treatments in the mainplots viz. W₀ = no irrigation, W₁ = irrigation of 5 cm at 4 weeks after planting, W₂-W₁ + irrigation(s) of 5 cm each at irrigation water to cummulative pan evaporation (IW/CPE) ratio of 0.75 and W₃- W₁ + irrigation(s) of 5 cm eacht at IW/CPE ratio of 0.50. The sub-plot tillage depth treatments were: A-7.5 cm (traditional), B-15 cm, C-22.5 cm, D-22.5 cm practised in alternate wheat seasons. Measurements were made of grain and straw yield, soil water depletion and water expense efficiency.Irrigation had no effect on grain or straw yield. Tillage to 15 cm increased wheat yield by about 15% over traditional depth to ploughing. In general, deep tillage coupled with one irrigation at four weeks after planting produced the largest wheat yield.Soil water depletion (SWD) in the 0–90 cm profile was greatest in the treatment receiving two irrigations, one at 4 weeks and again at IW/CPE ratio of 0.50. The average SWD in this treatment was 113 in 1982–83 and 82 mm in 1983–84. Plots receiving traditional tillage (7.5 cm) had the greatest SWD. Total water expense were the greatest in treatments receiving three irrigations. The maximum water expense efficiency (WEE) of wheat was observed in the non-irrigated plots in 1982–83 and 1983–84, respectively. Deep tillage treatments, in general, had significantly greater WEE than those under traditional ploughing. Intensive irrigation and efficient soil and water management are important factors in enhancing crop productivity. The former not only permits judicious water use but also better utilization of other production factors thereby leading to increased crop yield which, in turn, helps stabilize the farming economy. The best way to meet increasing demand for water is to adopt efficient water management practices to increase water use efficiency.Irrigation should aim at restoring the soil water in the root zone to a level at which the crop can fully meet its evapo-transpiration (ET) requirement. The amount of water to be applied at each irrigation and how often a soil should be irrigated depend, however, on several factors such as the degree of soil water deficit before irrigation, soil types, crops, and climatic conditions (Chaudhury and Gupta 1980).Knowledge of movement of water through the soil is imperative to efficient water management and utilization. The presence of a dense pan impedes water movement into the sub-soil. As a result, the top soil becomes saturated by irrigation and sensitive dryland crops can fail as this plough layer impedes the penetration of roots into deeper soil layers and decreases water extraction. Crops growing in these soils often undergo severe water stress within 5–8 days after rainfall or irrigation (Lowry et al. 1970). Due to decrease rates of water flow, the lower soil layer may remain unsaturated and as a result, the recharge and soil water storage in the profile are considerably decreased (Sur et al. 1981).In Bangladesh, ploughpans develop to varying degree in almost all ploughed soils (Brammer 1980). They are particularly marked in soils which are puddled for transplanted rice cultivation where the pan is usually only 8–10 cm below the soil surface and 3–5 cm thick. Its presence is generally regarded as advantageous for cultivation of transplanted rice in that it prevents excessive deep percolation losses of water. But in the same soil this cultivation for a subsequent dryland crop would adversely affect yield. A slight modification of the plough layer could enable good yields of both rice and a dryland crop to be obtained in the same soil in different seasons (Brammer 1980). The sub soils have a good bearing capacity, both when wet and dry and the pan can easily be reformed, if desired, for cultivating transplanted rice after a dryland crop like wheat.Professor of Soil Science, Dhaka University, Dhaka, Bangladesh     

Effect of different drip irrigation regimes on sugar beet (Beta vulgaris L.) yield, quality and water use efficiency in Middle Anatolian, Turkey

Agricultural production has forced researchers to focus on increasing water use efficiency by improving either new drought-tolerant plant varieties or water management for arid and semi-arid areas under water shortage conditions. A field study was conducted to determine effects of seasonal deficit irrigation on plant root yield, quality and water use efficiency (WUE) of sugar beet for a 2-year period in the semi-arid region. Irrigations were applied when approximately 50–55% of the usable soil moisture was consumed in the effective rooting depth at the full irrigation (FI) treatment. In deficit irrigation treatments, irrigations were applied at the rates of 75, 50 and 25% of full irrigation treatment on the same day. Irrigation water was applied by a drip irrigation system. Increasing water deficits resulted in a relatively lower root and white sugar yields. The linear relationship between evapotranspiration and root yield was obtained. Similarly, WUE was the highest in DI25 irrigation conditions and the lowest in full irrigation conditions. According to the averaged values of 2 years, yield response factor (k _y ) was 0.93 for sugar beet. Sugar beet root quality parameters were influenced by drip irrigation levels in both years. The results revealed that irrigation of sugar beet with drip irrigation method at 75% level (DI25) had significant benefits in terms of saved irrigation water and large WUE, indicating a definitive advantage of deficit irrigation under limited water supply conditions. In an economic viewpoint, 25% saving of irrigation water (DI25) caused 6.1% reduction in the net income.     

夏玉米不同生育期亏缺-复水对蒸发蒸腾和产量的影响

[目的]探究不同时间尺度下夏玉米蒸发蒸腾量的变化规律.[方法]试验在夏玉米3个生育阶段(出苗—拔节期、拔节—抽雄期、抽雄—灌浆期)分别设置3个灌水水平(充分灌溉:100％ETa;中度水分亏缺:80％ETa;重度水分亏缺:60％ETa),其中ETa为蒸渗仪实测的充分灌溉条件下的蒸发蒸腾量,采用正交试验设计,共9个处理(C...     

Response of wheat to saline irrigation and drainage

The response of wheat (Triticum aestiuum L.) to varying depths of irrigation, quantity of water applied and to the drainage conditions was studied in 2 m × 2 m × 2 m size lysimeters filled in with a sandy loam soil. Saline water with an electrical conductivity of 8.6 dS m⁻¹ was used for irrigation. The treatments included four irrigations of 5 cm depth, four irrigations of 7 cm, and three irrigations of 9 cm, scheduled on the basis of cumulative pan evaporation, while the drainage conditions were represented by the drained and undrained lysimeters. Another treatment, using good quality water for irrigation, represented the potential yield of the crop. The growth parameters, as well as the yield, showed an improvement with larger irrigation depth increments in the drained lysimeters. But, in contrast, in the undrained lysimeters, the yield was reduced with larger irrigation depth increments, mainly due to a sharp rise in water table depth during the irrigation cycles. The rise and fall in water table showed a high sensitivity and were also highly disproportionate to the irrigation and evapotranspiration events. The yield tended to be higher with a smaller depth of water applied more frequently in the undrained lysimeters. But, in view of the limitations of conventional surface irrigation to apply water in smaller depth increments, an improved drainage is imperative for cropping in shallow saline water table conditions.     

水分调亏对地下滴灌夏玉米田水热动态的影响

通过北京地区地下滴灌夏玉米田间试验,研究了前期不同程度水分亏缺对土壤水热和夏玉米冠层温度、株高、叶面积指数及产量的影响。结果表明:在20～60 cm土层,除重度亏水处理外,其他处理的土壤含水率均在高位平稳变化;在60～100 cm土层,丰水处理的土壤含水率最大;对不同深度的土层,轻度与中度亏水处理两者间的土壤含水率差异较小。受作物覆盖度和亏水程度的影响,拔节期各处理间土壤温度和冠层温度有明显差异;在较浅土层(距地表30 cm和50 cm处)中,拔节期之前丰水处理的土壤温度较低,拔节期之后各处理间差异逐渐减小;在较深土层(距地表80 cm处)中,水分亏缺程度越大,土壤温度越高。轻度亏水处理能获得较高的产量,中度亏水处理能提高水分利用效率。     

Cotton response to high frequency surface irrigation

High frequency irrigation with surface irrigation methods has been proposed as a means to increase cotton productivity in cases where drip irrigation or other pressurized systems are not economically justifiable. Field studies were conducted in 1993 and 1994 to evaluate the effects of surface irrigation frequency on the growth, lint yield and water use for a semi-determinate cotton cultivar in central Arizona. Cotton was grown in level basins on a sandy loam under three irrigation treatments defined as low frequency irrigation for the whole season (L), high frequency irrigation for the whole season (H), and low frequency irrigation until the initiation of rapid fruiting, high frequency during rapid fruiting, and low frequency after rapid fruiting (LHL). The treatments were governed by the percentage of allowable soil water depletion within the effective root zone, and the allowable depletion targets for low and high frequency irrigation were 55 and 30%, respectively. An irrigation scheduling program calculated the soil water depletion within the estimated cotton root depth on a daily basis for each treatment and was used to project the dates and amounts for treatment irrigations. In 1993, seven, 14, and 11 irrigations and in 1994 eight, 13 and 10 irrigations were given to the L, H, and LHL treatments, respectively. The total amount of water applied including rainfall differed among the treatments by 4% in 1993 and by 1% in 1994. Soil water measurements indicated that actual soil water depletion within the estimated cotton root depth immediately before treatment irrigations was close to the intended treatment allowable depletion targets for the majority of the growing season. Cotton growth and lint yields were maximized under the H treatment, and yields in this treatment averaged 15 and 21% more lint than the L treatment for the first and second seasons, respectively. The LHL treatment, although not as effective in increasing crop productivity as the H treatment, out yielded the low frequency treatment by an average of 10% in the two seasons. Crop evapotranspiration determined from the soil water balance was 8 and 9% higher for the H than the L treatment and 3 and 5% higher for the LHL than the L treatment in 1993 and 1994, respectively.     

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

Irrigation water is a limited resource, and therefore irrigation practices must be rationalized for high water-use efficiency. Little is known about the influence of stored water in deep soils on the water needs and the post-sowing irrigation requirements of crops. A 3-year field experiment was conducted to determine the effects of combinations of light and heavy pre-sowing irrigations with two post-sowing irrigation regimes on yield, root growth, water use and water-use efficiency of wheat on a deep alluvial sandy loam soil. Post-sowing treatments consisted of (i) five 75-mm irrigations at five growth stages, and (ii) irrigations based on pan evaporation, i.e. at IW/PAN-E ratio of 0.75 (75 mm of irrigation water were provided as soon as the open-pan evaporation minus rainfall since previous irrigation was 100 mm).The latter regime required 175 mm less water than that with irrigation at growth stages. Profile water utilization was inversely related to post-sowing irrigation water. Where pre-sowing irrigation was light, post-sowing irrigations based on pan evaporation yielded significantly less than those based on growth stages. With heavy pre-sowing irrigation, irrigation based on the pan evaporation yielded as much as five irrigations at growth stages. The former decreased the mean water application by 153 mm and increased the water-use efficiency by 26%. Irrigation based on pan evaporation stimulated greater utilization of stored water by increasing the rooting density in deeper layers.It is indicated that for higher water-use efficiency and yield, wheat should be sown after a heavy pre-sowing irrigation, and post-sowing irrigation should be based on 0.75 pan evaporation.     

Yield response of greenhouse grown tomato to partial root drying and conventional deficit irrigation

Greenhouse grown tomato was used to test partial root drying (PRD), a newly developing irrigation technique to save irrigation water, in Spring- and Fall-planted fresh-market tomato (Lycopersicon esculentum L., cv. Fantastic) cultivar. The PRD practice simply requires wetting of one half of the rooting zone and leaving the other half dry, thereby utilizing reduced amount of irrigation water applied. The wetted and dry sides are interchanged in the subsequent irrigations. Six irrigation treatments were tested during the two-year work in 2000 and 2001: (1) FULL, control treatment where the full amount of irrigation water, which was measured using Class-A pan evaporation data, was applied to the roots on all sides of the plant; (2) 1PRD30, 30% deficit irrigation with PRD in which wetted and dry sides of the root zone were interchanged with every irrigation; (3) 1PRD50; (4) 2PRD50, 50% deficit irrigation with PRD in which wetted and dry sides of the root zone were interchanged every and every other irrigation, respectively; (5) DI30 and (6) DI50, 30 and 50% deficit irrigations, respectively. The defined deficit levels were all in comparison to FULL irrigation. During the first year study in 2000, only three treatments (FULL, 1PRD30 and 2PRD50) were tested. Five treatments with exception of 2PRD50 were included in 2001. The FULL irrigation treatment, in Spring-planted tomato having a 153 day growth period, yielded 110.9 t ha⁻¹. The resulting irrigation-water-use efficiency (IWUE) was 321.8 kg (ha mm)⁻¹. The 1PRD50 treatment gave 86.6 t ha⁻¹, which was not statistically different (P ≤ 0.05) from the FULL irrigation (the control) and had 56% higher IWUE. Although yield differences were not statistically significant in Fall-planted tomato, the highest fruit yield was again obtained under FULL irrigation treatment (205.2 t ha⁻¹) over a growth period of 259 days after transplanting. The PRD treatments had 7–10% additional yield over the deficit irrigation receiving the same amount of water. The PRD treatments gave 10–27% higher marketable tomato yield (>60 g per fruit), compared with the DI treatments. Abscisic acid (ABA) concentrations measured in fresh leaf tissue was the highest under PRD practice relative to FULL and DI treatments. The high ABA content of fresh-leaf tissue observed in the work supports the root signalling mechanism reported earlier in plants having undergone partial root drying cycles.     

The influence of soil water potential on the flowering pattern,pod set and yield of snap beans (Phaseolus vulgaris L.)

Summary The effect of the soil water potential on pod yield of snap beans grown with a series of irrigation frequencies was studied over two seasons. The treatments were to furrow-irrigate either weekly or fortnightly during the preflowering period, and each treatment then received weekly or fortnightly irrigations to harvest. These treatments were compared with trickle irrigation applied daily in the first season and every second day in the second season. The irrigation frequencies during the pre-flowering period did not influence the pod yield. However, in the second season plants given the trickle irrigation treatment produced more early flowers and set pods earlier than those in the other treatments. Consequently the pods were harvested three days earlier from plants on this treatment.Pod yield was determined by the irrigation treatments applied after flowering. The highest yield was similar in each season (16.7 t ha^–1) and was produced under trickle irrigation. Fortnightly irrigations during the pod-fill phase reduced yield by 56% in the first season and 41% in the second season when compared with trickle irrigation. The pod yield was reduced by 0.5 t ha^–1 each day the soil water potential at 30 cm depth was less than –50 kPa. This relationship accounted for about 77% of the variation in pod yield.     

Yield response of a semi-dwarf wheat variety to irrigation on a calcareous brown flood plain soil of Bangladesh

Field studies were conducted to determine the yield performance of a semi-dwarf high yielding variety of wheat (Triticum aestivum L., cv. ‘Sonalika’) in response to irrigation provided at various critical stages of growth. Determination of an irrigation schedule for most efficient water management was attempted. The study, conducted on a calcareous brown flood plain soil, comprised a randomized block design experiment with eight irrigation treatments applied at critical growth stages.The yield of wheat was the highest and the irrigation efficiency maximum, when two irrigations, totalling 9.5 cm, were given at tillering and booting stages. The quantity of irrigation water applied was calculated on the basis of deficit from field capacity level of soil water content. The lowest grain yields were obtained in treatments receiving either no irrigation or only one irrigation at the grain-filling stage. The percent increase over control (no irrigation) in grain yield, due to various irrigation treatments, ranged from 21 to 92%. The data revealed that the depletion of soil water increased as the amount of irrigation water increased.The results indicate that the present yield levels of wheat in Bangladesh can easily be increased by 50–100% by irrigating with only one-third to one-half of the water currently being used, provided it is scheduled and managed efficiently, keeping in view the need of the crops as well as the soils.     

不同生育期灌水和施氮对春玉米农田硝态氮迁移及产量的影响

通过对大田春玉米进行不同生育期灌水和施氮处理,研究了不同灌水和施氮对玉米农田硝态氮运移和产量的影响。结果表明:生物产量和籽粒产量及其灌溉水利用效率有随施氮量增加而增大的趋势。与全生育期灌水比较,任何生育期不灌水处理都造成生物产量和籽粒产量降低,而生育期不灌水处理增加了灌溉水利用效率,两个生育期不灌水处理的生物产量和籽粒产量的灌溉水利用效率最高。在春玉米生长阶段,拔节期,抽穗期和成熟期不灌水对生物产量影响显著,抽穗期不灌水、苗期与灌浆期不灌水、拔节期期和灌浆期不灌水处理显著影响籽粒产量。     

Potato water use and yield under furrow irrigation

Field experiments were conducted to study the effects of plant-furrow treatments and levels of irrigation on potato (Solanum tuberosum L.) water use, yield, and water-use efficiency. The experiments were carried out under deficit irrigation conditions in a sandy loam soil of eastern India in the winter seasons of 1991/92, 1992/93, and 1993/94. Two plant-furrow treatments and two levels of irrigation were considered. The two plant-furrow treatments were F₁ - furrows with single row of planting in each ridge with 45 cm distance between adjacent ridges, and F₂ - furrows with double rows of planting spaced 30 cm apart in each ridge with 60 cm distance between adjacent ridges. The two levels of irrigation (LOI) were I₁ - 0.9 IW/CPE and I₂ - 1.2 IW/CPE, where IW is irrigation water of 5 cm and CPE is cumulative pan evaporation. Treatment F₂ produced highest tuber yield in all years with average value of 10,610 kg ha ^-1 and 12,780 kg ha ^-1 at LOI of I₁ and I₂, respectively. On average, six irrigations with a total of 25 cm, and seven irrigations with a total of 30 cm were required for both treatments F₁ and F₂ at LOI of I₁ and I₂, respectively. Treatment F₂ resulted in a significantly higher number of branches and tubers per plant, foliage coverage and water-use efficiency for both irrigation levels than treatment F₁. Average daily crop evapotranspiration was found to range from 1.1 to 3.4 mm and from 1.2 to 3.9 mm for treatment F₁ and from 1.1 to 3.6 mm and from 1.2 to 4.0 mm for treatment F₂ at LOI of I₁ and I₂, respectively.     

Yield and water use of eggplants (Solanum melongena L.) under full and deficit irrigation regimes

Field experiments were conducted in 2008 and 2009 to determine the effects of deficit irrigation on yield and water use of field grown eggplants. A total of 8 irrigation treatments (four each year), which received different amounts of irrigation water, were evaluated. In 2008, deficit irrigation was applied at full vegetative growth (WS-V), pre-flowering (WS-F) and fruit ripening (WS-R), while in 2009 deficit irrigation was applied during the whole growing season at 80 (WS-80), 60 (WS-60) and 40% (WS-40) of field capacity. Deficit-irrigated treatments were in both years compared to a well irrigated control. Regular readings of soil water content (SWC) in 2008 and 2009 showed that average soil water deficit (SWD) in the control was around 30% of total available water (TAW) while in deficit-irrigated treatments it varied between 50 and 75% of TAW. In 2008, deficit irrigation reduced fruit fresh yield by 35, 25 and 33% in WS-V, WS-F and WS-R treatments, respectively, when compared to the control (33.0 t ha⁻¹). However, the reduction in fresh yield in response to deficit irrigation was compensated by an increase in fruit mean weight. Results obtained in 2009 showed that fruit fresh yield in the control was 33.7 t ha⁻¹, while it was 12, 39 and 60% less in WS-80, WS-60 and WS-40 treatments, respectively. On the other hand, fruit dry matter content and water productivity were found to increase significantly in both years in deficit-irrigated treatments. Applying deficit irrigation for 2 weeks prior to flowering (WS-F) resulted in water saving of the same magnitude of the WS-80 treatment, with the least yield reduction, making more water available to irrigate other crops, and thereby considered optimal strategies for drip-irrigated eggplants in the semi-arid climate of the central Bekaa Valley of Lebanon.     

Water pillow irrigation compared to furrow irrigation for soybean production in a semi-arid area

Field studies were done in 2003 and 2006 to evaluate the performance of water pillow (WP) irrigation as an alternative to furrow irrigation (FI) for soybean growth in semi-arid climatic conditions. There were four irrigation treatments: two of which (FI and WP_1.0) were full irrigation, in that the water deficit in the soil profile (0.9 m) was brought to field capacity in 10-day intervals. The other two treatments (WP_0.75 and WP_0.50) were deficit irrigation treatments, and received 75% and 50% of WP_1.0 irrigation amount. The highest seed yield was achieved with the WP_1.0 treatment. Irrigation water use efficiency (IWUE) and water use efficiency (WUE) were influenced significantly by the irrigation methods and levels (P ≤ 0.05). The highest values of WUE and IWUE were obtained by the WP_0.75 and WP_0.50 treatment, respectively, in both study years. However, the smallest irrigation amount resulted in lower total yield for the WP_0.50 treatment, and is not recommended. In conclusion, the WP_0.75 treatment is recommended for soybean production in order to attain higher values of IWUE and WUE, and to conserve water and maximize yield with the same volume of water.     

Response of cotton to different soil water deficits on clay soils

Summary Cotton was grown under sprinkler irrigation on a silty clay soil at Keiser, Arkansas, for the 1987, 1988 and 1989 growing seasons. Irrigation treatments consisted of maximum soil water deficits (SWD) of 25, 50 and 75 mm and a nonirrigated control. While the irrigated treatments were significantly different from the control for plant height and total seedcotton yield, significant differences among the three irrigated treatments were only observed for plant height. Yields were significantly lower in 1989 than in the other two years of the study, due in part to later planting. The 3-year averages for total seedcotton yield were 3280 and 2870 kg ha^–1 for irrigated and nonirrigated, respectively, for an average increase corresponding to irrigation of 416 kg ha^–1 or 14.5% of the nonirrigated yield. The maximum increase was observed in 1988 as 602 kg ha^–1 or 20.6% of the nonirrigated yield for that year. The 75 mm allowable SWD was the most efficient treatment and resulted in a 3-year average of 3.85 kg ha^–1 additional seedcotton (above the nonirrigated) harvested for each 1 mm of irrigation applied. Maintaining the SWD below a 75 mm maximum required an average of four irrigations and 110 mm of irrigation water per year.     

不同灌溉制度对冬小麦产量与水分利用效率的影响

以河北黑龙港地区常用冬小麦品种石麦15和济麦22为试验材料,研究了不同灌溉制度对冬小麦产量与水分利用效率的影响。结果表明,3种灌水处理下,石麦15的产量均高于济麦22。其中石麦15灌1水处理与济麦22灌2水处理产量相当,石麦15灌1水处理与济麦22灌3水处理产量相当,石麦15表现出节水高产的优势。石麦15灌2水处理的水分利用效率最高,达20.22 kg/(mm.hm2),比灌2水的济麦22高21.9%,比灌3水的济麦22高7.4%,说明石麦15灌2水处理在所有6个处理中表现最优。     

Growth,yield and soil water extraction of irrigated and dryland peanuts in South Sulawesi,Indonesia

Summary Irrigation at 35 and 70 mm of pan evaporation applied during the pre and/or post early podfilling stages increased pod yield of Spanish peanuts (100 day maturity) three fold compared to a dryland crop. There was no difference in pod yield in crops receiving 12 compared to 6 irrigations. Soil water sampling immediately after irrigations on selected treatments revealed that infiltration of irrigation water was probably restricted to less than ca. 20 cm, a response which resulted in poor soil water replenishment and low irrigation efficiency (Fig. 3). Even though roots extracted soil water below the compaction layer which was at 20 cm severe crop water deficits had developed by the end of irrigation cycles during later but not early stages of growth. The dryland crop, which received no rainfall during the season, presumably extracted significant amounts of soil water at depths to and below 1.2 m (Fig. 3). Despite producing ca. 2.9 t ha^-1 of total dry matter yield, pod yield was extremely low (0.5 t ha^-1) arising from low pod numbers and high percentage of empty pods.This research was funded by the Australian Centre for International Agricultural Research (ACIAR-Project 8419) in collaboration with the Agency for Agricultural Research and Development (AARD).     

水肥耦合对苹果幼树产量、品质和水肥利用的效应

为探明半干旱地区苹果幼树水肥精准管理模式,研究了水肥耦合对3 a生苹果幼树生长、产量、品质及水肥利用的效应,试验设置4个灌水水平,其灌水上下限分别为田间持水率的75%~85%(W1)、65%~75%(W2)、55%~65%(W3)、45%~55%(W4);3个施肥水平(N-P2O5-K2O),即高肥:30-30-10 g/株(F1)、中肥:20-20-10 g/株(F2)、低肥:10-10-10 g/株(F3)。结果表明:苹果幼树萌芽开花期至新梢生长期控水控肥可有效调控苹果幼树植株和叶面积的增长;苹果产量最高和最低的处理分别为F1W1和F3W4(F1W1比F3W4增加139.1%),产量与干物质质量间相关关系的决定系数R2为0.908 5,达到了极显著水平;增加灌水量提高了苹果着色指数却降低其果形指数,亏水处理和增加施肥量有利于提高苹果硬度;轻度亏缺(F2)灌溉处理下,增加施肥量有利于提高苹果维生素C含量;灌水量对苹果可溶性固形物和可溶性糖影响不显著,但增加施肥量有利于提高苹果可溶性固形物和可溶性糖的含量;施肥量对苹果可滴定酸和糖酸比影响不显著,但增加灌水量可降低苹果可滴定酸含量,提高苹果糖酸比;高水低肥处理能够产生较高的肥料偏生产力(PFP);水分利用效率(WUE)最大值基本上出现在F2W2处理,与F1W1相比,虽然产量减小7.5%,但耗水量却减小16.7%,WUE增加11.2%,高水高肥的F1W1处理并不能得到最大的WUE,最大的WUE出现在F2W2处理。由此可见,F2W2处理是苹果幼树生长、产量、品质以及水肥利用效率方面的最佳水肥组合,达到了节水、节肥的最佳水肥耦合模式。