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1.
Summary Cowpea and mung bean were subjected to three irrigation schedules during summer dry months (May–June). In general, cowpea had higher rates of net photosynthesis (P n ,Figs. 1, 2), dark respiration (R d ,Table 1), absorption of photosynthetically active radiation (PAR, Table 2), and growth (Fig. 7) than mung bean. Mung bean reflected more PAR and maintained a slightly cooler canopy than cowpea (Table 2). Moisture stress decreased P n , R d ,absorption coefficient of PAR, evaporative cooling and growth in both the species. However, the reductions in P n rates of stressed leaves were more than the decreases in R d .Restoration of water supply to stressed cowpea resulted in a more rapid recovery of growth as compared to mung bean.  相似文献   

2.
A 2-year study was carried out from 2006 to 2007 to determine the most suitable irrigation management for maximum dry bean (Phaseolus vulgaris L.) seed yield and water use efficiency (WUE) in southern Alberta, Canada. Six irrigation management treatments were evaluated in this study, including scheduling irrigation based on soil water depletion within a 0.30-m root zone, a 0.60-m root zone, and a split 0.30/0.60-m root zone (a 0.30-m root zone during vegetative growth stages and a 0.60-m root zone at flowering), and 12, 25, and 50-mm applications of irrigation water based on soil water depletion in a 0.60-m root zone. Plant available soil water was maintained above 60% in all irrigation management treatments. A significant increase in average seed yield (15% in 2006 and 46% in 2007) and in WUE (30% in 2006 and 50% in 2007) was found in more frequently irrigated treatments (0.30-m root zone, split 0.30/0.60-m root zone, and 12-mm application) compared to less frequently irrigated treatments (0.60-m root zone and 50-mm application). Dry bean seed yield and WUE may be maximized by keeping the majority of roots moist.  相似文献   

3.
Summary Field investigations carried out at the Indian Institute of Horticultural Research, Bangalore, during 1985–1986 and 1986–1987 with French bean crops indicated that irrigation when soil matric potential at 0.15 m depth reached — 45 kPa resulted in highest dry matter production, green pod yield, nutrient uptake and water use efficiency (WUE) as compared to irrigations scheduled at -65 or -85 kPa. The difference in pod yield between irrigations scheduled at -25 and -45 kPa was not significant. Increasing soil moisture stress increased the canopy temperature and adversely affected plant water relations. There was a quadratric relationship between green pod yield and evapotranspiration (ET) with the yield-maximising ET ranging between 268 and 299 mm. Nitrogen fertilization significantly increased green pod yield, nutrient uptake and WUE but had no marked effect on water relations and canopy temperature.Contribution No. 234/88 of Indian Institute of Horticultural Research, Bangalore, India  相似文献   

4.
The effects of high temperature stress and supplemental irrigation on seed yield and water use efficiency (WUE) of canola (Brassica napus L.) were studied in a field experiment conducted for 2 years. The experiment was a randomized complete block design arranged in split plot, conducted at Agricultural Research Station of Gonbad, Iran. It was arranged in two conditions, i.e. supplemental irrigation and rainfed. Two cultivars of canola (Hyola401 and RGS003) as subplots were grown at five sowing dates as main plots. The sowing dates were 9 November, 6 December, 5 January, 4 February and 6 March in 2005-2006 and 6 November, 6 December, 5 January, 4 February and 6 March in 2006-2007, to have a wide range of environmental conditions around flowering and seed filling periods, and to coincide reproductive stages of the crop with high temperature stress. Seed yield was improved due to field management practices, such as supplemental irrigation and optimum sowing date. Supplemental irrigation was an efficient practice to mitigate water stress, and to increase aboveground dry matter and seed yield. There was a strongly negative relationship between seed yield and air temperature during reproductive stages. Delay in sowing led to more rapid developmental of canola, decreased aboveground dry matter, leaf area index (LAI), harvest index (HI), WUE, and seed yield. Achieving a high aboveground dry matter was an essential prerequisite for high reproductive growth and a high seed yield. Greater seed yield and WUE at first sowing date were associated with greater LAI and aboveground dry matter, and lower temperatures during reproductive stages. The results support the view that WUE can be used as an indirect selection criterion for seed yield in genotypic selection.  相似文献   

5.
The effect of irrigation with water at salinity concentrations of 2.6 and 5.2 dS m–1 on the growth of pure swards of six cultivars of white clover (Trifolium repens L.) was examined over three irrigation seasons at Tatura, Victoria, Australia. After two irrigation seasons, soil EC e levels increased to 6 dS m–1 at 0–60 cm depth in the higher salinity treatment resulting in highly significant (p < 0.001) reductions in shoot dry matter production, flowering densities and petiole and stolon densities. These saline conditions also increased (p <0.001) concentrations of Cl and Na in the shoots and reduced (p < 0.001) leaf water potentials and canopy photosynthetic efficiency rates especially at high temperatures. In contrast, root growth increased at shallow depths (0–15 cm) under both saline irrigation treatments (p <0.001). Cultivars differed significantly in salt tolerance (p < 0.001), with cultivars Haifa and Irrigation exhibiting superior tolerance in terms of lower reductions in herbage yield (p <0.05) and petiole densities (p <0.001) during one irrigation season and lower concentrations of Na and Cl in the shoots (p <0.05) compared with the other four cultivars (Aran, Kopu, Pitau and Tamar). In addition, canopy photosynthetic efficiency rates (A *) in plots irrigated with water at 5.2 dS m–1 were higher in cultivar Haifa compared with cultivar Tamar (p <0.05). The salt tolerance ranking obtained for the six cultivars was in broad agreement with earlier greenhouse studies. Consequently, it appears that, while white clover is an extremely salt-sensitive species, it is possible to grow cultivars which display greater salt tolerance than other cultivars and which provide some scope to increase, or at least to maintain, pasture yields in areas where the soil salinity is low to moderate or where pumped saline groundwater is re-used for Irrigation.  相似文献   

6.
The North China Plain (NCP) is one of the main productive regions for winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) in China. However, water-saving irrigation technologies (WSITs), such as sprinkler irrigation technology and improved surface irrigation technology, and water management practices, such as irrigation scheduling have been adopted to improve field-level water use efficiency especially in winter wheat growing season, due to the water scarcity and continuous increase of water in industry and domestic life in the NCP. As one of the WSITs, sprinkler irrigation has been increasingly used in the NCP during the past 20 years. In this paper, a three-year field experiment was conducted to investigate the responses of volumetric soil water content (SWC), winter wheat yield, evapotranspiration (ET), water use efficiency (WUE) and irrigation water use efficiency (IWUE) to sprinkler irrigation regimes based on the evaporation from an uncovered, 20-cm diameter pan located 0-5 cm above the crop canopy in order to develop an appropriate sprinkler irrigation scheduling for winter wheat in the NCP. Results indicated that the temporal variations in SWC for irrigation treatments in the 0-60-cm soil layer were considerably larger than what occurred at deeper depths, whereas temporal variations in SWC for non-irrigation treatments were large throughout the 0-120-cm soil layer. Crop leaf area index, dry biomass, 1000-grains weight and yield were negatively affected by water stress for those treatments with irrigation depth less than 0.50E, where E is the net evaporation (which includes rainfall) from the 20-cm diameter pan. While irrigation with a depth over 1.0E also had negative effect on 1000-grains weight and yield. The seasonal ET of winter wheat was in a range of 206-499 mm during the three years experiments. Relatively high yield, WUE and IWUE were found for the irrigation depth of 0.63E. Therefore, for winter wheat in the NCP the recommended amount of irrigation to apply for each event is the total 0.63E that occurred after the previous irrigation provided total E is in a range of 30-40 mm.  相似文献   

7.
Three cowpea varieties and one maize variety were subjected to varying irrigation treatments, ranging from water deficits to over-irrigation, on a silty loam soil classified as an Alfisol at Ile-Ife, Nigeria. There was a strong curvilinear relation between cowpea yield and evapotranspiration (R2 = 0.86 for dry matter yield and R2 = 0.87 for dry seed yield). The values of the correlation coefficient dropped to 0.62 and 0.66 for dry matter and seed yields, respectively, when a linear relation was used. When data for over-irrigated fields were omitted from the calculation, a linear relationship yielded R2 values close to unity (R2 = 0.99). Similar results were obtained on maize dry matter and grain yields in relation to evaporation.  相似文献   

8.
Effects on water use, green bean yield, irrigation water-use efficiency (IWUE), water-use efficiency (WUE), plant dry weight and crop water relationship were investigated for two-drip irrigation techniques and four irrigation water levels in the Mediterranean region of Turkey. The treatments were conventional (SDI) and alternating subsurface drip irrigation (SPRD). At each irrigation event, half of the volume of water applied to the SDI was applied to one side of the crop, representing the partial rootzone-drying treatment. All treatments received 295 mm of irrigation during crop establishment, prior to beginning the different irrigation regimes. Differing irrigation amounts corresponded to four crop-pan coefficients (Kcp1 = 0.6, Kcp2 = 0.8, Kcp3 = 1.0 and Kcp4 = 1.2), appropriate to pan data. Total water applied to the SDI and SPRD treatments ranged from 366 to 437 mm and from 331 to 366 mm, respectively, depending on Kcp values, with water uptake varying from 396 to 470 mm and 364 to 409 mm, respectively. While differences of green bean yield and dry plant weights were not significantly affected by the SDI and SPRD irrigation techniques, the overall irrigation water saving was found to be 16% for the SPRD irrigation treatment compared with the SDI treatment. SPRD irrigation techniques increased IWUE, WUE, and slopes of yield water relationships. Increase in slopes of the yield–irrigation water and yield–water-use function of SPRD according to the equivalent slopes of the SDI were 215.8 and 151.4%, respectively. SPRD increased the green bean yield response factor (ky) with value of 128.4% according to the equivalent slopes of the SDI. In conclusion, irrigation scheduling based on a 0.8 crop-pan coefficient is recommended for conventional SDI, with 1.0 being more appropriate for partial rootzone-drying practice.  相似文献   

9.
Summary A field trial was conducted to determine the response of rapeseed (Brassica napus cv. Marnoo) to two irrigation treatments and six nitrogen fertilizer treatments. Dry matter accumulation, leaf area development and seed yield were measured. The dry matter and seed yield response to applied nitrogen was greater under irrigated compared to rainfed conditions. Maximum seed yield (approx. 3.8 t ha–1) was obtained from the irrigated treatment receiving 100 kg N ha–1 applied at sowing. This high rate of N application at sowing led to more rapid leaf area development and higher maximum LAI compared to treatments supplied with split application of the same amount of N at sowing and rosette stages. Greater partitioning of dry matter into the leaf component and higher specific leaf areas under the higher N regime were largely responsible for this increase. Higher maximum LAI's were associated with greater numbers of pods per plant, which combined with longer leaf area duration led to higher final seed yields.  相似文献   

10.
Summary The growth response of kenaf (Hibiscus cannabinus L.) to four irrigation schedules based on leaf water potential l was evaluated in a semi-arid tropical environment. Total dry matter production was unaffected by regimes in which the mean value of leaf water potential l (mean of solar noon and dawn value) did not fall below –1.26 MPa. Stem elongation was more sensitive than dry matter accumulation to plant water stress. — The economic yield for paper pulp production (i. e. total plant dry matter production minus that of the foliage and upper 60 cm of stem) increased with the frequency of irrigation. — Growth recovery by kenaf following a period of water stress was examined. Alleviation of water stress 10 weeks after irrigation, when l was –1.60 MPa, produced stem elongation rates that were greater than those of plants previously receiving irrigation. This ability to withstand water stress and partially compensate in growth following alleviation of the stress indicates that the kenaf crop has stress response features suitable for rainfall only production under semi-arid tropical conditions. — Irrigation schedules based on l resulted in water applications tailored to crop requirements in that water use increased, and the time interval between irrigation decreased, with increasing canopy development as well as with increasing evaporative demand. However, erratic fluctuations in l between irrigations make scheduling by this method difficult and the use of daily mean, dawn or noon values of l for scheduling irrigation of kenaf cannot be recommended in environments of high evaporative demand. The factors contributing to these fluctuations in (l) are discussed.  相似文献   

11.
水肥耦合对棉花产量和氮累积利用的影响   总被引：2，自引：0，他引：2  
研究膜下滴灌施肥条件下,不同滴灌水量和滴灌施肥用量对棉花产量、氮素动态累积和氮素利用效率的影响。通过设置5个滴灌施肥水平和3个水分水平的完全组合处理以及一个不施肥对照处理,研究了水肥耦合对棉花干物质动态累积量、籽棉产量、氮动态累积量和氮素利用效率的影响。在收获后棉花地上部分器官质量从高到低依次为棉铃,茎秆和叶,而氮素主要集中在棉铃内部,其次是叶片,茎秆最少。灌溉水量显著增加了棉花叶片,茎秆和棉铃质量,从而增加了干物质量和籽棉产量,同时灌溉水量显著增加氮累积量和氮肥利用率。水肥对氮肥偏生产力,氮肥农学效率和氮肥生理利用率影响显著。灌溉水量降低至60%ETc会抑制棉花对氮素的吸收,使干物质量和籽棉产量下降,但可以显著提高氮肥利用率,氮肥偏生产力,氮肥农学效率。在本试验条件下,灌水量在380 mm,施肥量(N-P2O5-K2O)为(250-100-50)kg/hm2时,可以获得低于最高产量6%的籽棉产量,并节省15%的灌水量和16.7%施肥量。  相似文献   

12.
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.  相似文献   

13.
A four-year trial was set up to test the feasibility of growing oleic sunflower in a very strongly saline wasteland with drip irrigation in the Ningxia plain of Northwest China. The soil salinity expressed as electrical conductivity of the saturation paste extract (EC e ) was around 28 dS/m, and soil nutrient was deficient in the upper 120 cm depth. The experiment included five soil matric potential (SMP) treatments, with the SMP at 20-cm depth immediately under the emitters maintained to be higher than ?5, ?10, ?15, ?20 and ?25 kPa after sunflower establishment. Drip irrigation consistently created a favourable soil moisture and low-salinity region in the root zone when the SMP was maintained higher than ?25 kPa. The sunflower dry seed yield decreased by 3.8 % for each unit increase in seasonal average soil salinity in the root zone. Plant vegetative growth, yield characteristics, irrigation frequency and irrigation amount all increased with the increase in SMP from ?25 to ?5 kPa, and the highest irrigation water use efficiency was available when the SMP was between ?10 and ?15 kPa (the amount of applied water was around 750 mm). Leaching of salts by drip irrigation gradually turned the very strongly saline soil into a moderately saline soil. This research suggests that drip irrigation can be successfully used in oleic sunflower cultivation in this highly saline soil and a SMP threshold between ?10 and ?15 kPa is suggested for irrigation scheduling.  相似文献   

14.
Summary Rapid drying of surface layers of coarse-textured soils early in the growth season increases soil strength and restricts root growth. This constraint on root growth may be countered by deep tillage and/or early irrigation. We investigated tillage and irrigation effects on root growth, water use, dry matter and grain yield of wheat on loamy sand and sandy loam soils for three years. Treatments included all combinations of two tillage systems i) conventional tillage (CT) — stirring the soil to 10 cm depth, ii) deep tillage (DT) — subsoiling with a single-tine chisel down to 35–40 cm, 40 cm apart followed by CT; and four irrigation regimes, i) I0 — no post-seeding irrigation, ii) I1 — 50 mm irrigation 30 days after seeding (DAS), iii) I2 — 50 mm irrigation 30 DAS and subsequent irrigations of 75 mm each when net evaporation from USWB class A open pan (PAN-E) since previous irrigation accumulated to 82 mm, and iv) I3 — same as in I2 but irrigation applied when PAN-E accumulated to 62 mm. The crop of wheat (Triticum aestivum L. HD 2329) was fertilized with 20kg P, 10kg K and 5kg Zn ha–1 at seeding. The rate of nitrogen fertilization was 60 kg ha–1 in the unirrigated and 120 kg ha–1 in the irrigated treatments. Tillage decreased soil strength and so did the early post-seeding irrigation. Both deep tillage and early irrigation shortened the time needed for the root system to reach a specified depth. Subsequent wetting through rain/irrigation reduced the rate of root penetration down the profile and also negated deep tillage effects on rooting depth. However, tillage/irrigation increased root length density in the rooted profile even in a wet year. Better rooting resulted in greater profile water depletion, more favourable plant water status and higher dry matter and grain yields. In a dry year, the wheat in the DT plots used 46 mm more water, remained 3.3 °C cooler at grain-fill and yielded 68% more grain than in CT when unirrigated and grown in the loamy sand. Early irrigation also increased profile water depletion, more so in CT than DT. Averaged over three years, grain yield in DT was 12 and 9% higher than in CT on loamy sand and sandy loam, respectively. Benefits of DT decreased with increase in rainfall and irrigation. Irrigation significantly increased grain yield on both soils, but the response was greatly influenced by soil type, tillage system and year. The study shows that soil related constraints on root growth may be alleviated through deep tillage and/or early irrigation.  相似文献   

15.
This study was conducted in order to determine the effect of drip line spacing, irrigation regimes and planting geometries of tomato on yield, irrigation water use efficiency (IWUE) and net return. The experiments were carried out in the conditions of Eskisehir in Central Anatolian part of Turkey, between 2003 and 2005, with cv. Dual Large F1 tomatoes (Lycopercion esculentum L). The maximum yield of 121.1 t ha−1 was obtained from the treatment in which both the lateral and row spacing were 1 m, and irrigated with water amount based on the percentage of canopy cover. The seasonal irrigation water amount of the treatment was 551 mm. Tomatoes yield of 109.9 t ha−1 was obtained under conditions of 491 mm seasonal irrigation water applied for the 2-m lateral spacing in which two plant rows (twin rows) were planted 0.35 m on either side of the lateral with a row spacing of 0.70 m across the drip lateral and 1.30 m in the interrow between each set of twin rows. Although water saving of 60 mm and investments economy of 40% were provided from the twin-row design, the yearly return of the design including one lateral for each row was US$ 1590 ha−1 higher than that the return of the twin-row design. The method of determination of irrigation water amount based on the percentage of canopy cover appeared to be the most reasonable and effective one in terms of the yield and IWUE. On the other hand, the maximum irrigation water use efficiency (22.3 kg m3) was obtained from 2-m lateral spacing and the percentage of canopy cover for calculation of the amount of irrigation water applied. Thus, canopy cover may be used successfully at any lateral design conditions.  相似文献   

16.
Irrigation for crops in a sub-humid environment   总被引：4，自引：0，他引：4  
Summary A four year study examined the effect of irrigating at various water deficits at different times in the growing season, in combination with a range of nitrogen fertilizer rates, on the growth, yield and quality of cotton. The major effect of irrigation treatment on growth was to increase leaf area and plant size; net assimilation rate in the vegetative phase was not affected by irrigation treatment. The initial rate of boll setting was slightly faster in low nitrogen and less frequent irrigation treatments, but by day 180 (immediately prior to defoliation), all treatments had 60% of total dry weight as bolls and 7% as leaf. The best irrigation strategy varied from year to year due to the variable rainfall pattern. Irrigation when 80% of the available soil moisture had been depleted in the first half of the season only decreased total lint yield by up to 12% in two of the four seasons. During the second half of the season the 80% level of depletion decreased yield by an average of 15% but gave an earlier crop. Yield was reduced by up to 17% if irrigation at 40–60% of available moisture depletion in the first half of the season was followed by irrigation at 80% of available moisture depletion in the second half of the season. A rainfed treatment yielded from 16 to 43% less than the heaviest yielding irrigation treatment. After irrigation there was evidence of poor aeration in the soil which was most severe and lasted the longest at 30 cm depth. Heaviest yields were obtained with 100–150 kgN ha–1, except in rainfed treatments where 0–50 kgN ha–1 was sufficient. Irrigation at only 40% of available moisture depletion decreased nitrogen uptake in all seasons. Treatment effects on fibre quality in these experiments were small and variable. Nitrogen fertilizer generally increased length and strength but decreased micronaire. Stress during boll filling decreased micronaire and length in two of the four seasons.  相似文献   

17.
Summary Experiments were conducted for wheat (Triticum aestivum L.) grown in the lysimeters with controlled irrigation at Berlin (FRG) and in field plots at Hisar (India) under different climatic conditions. Crop production functions, relating crop yield with evapotranspiration with and without the consideration of the time of water deficit during crop growth period, were derived. The derived functions and those previously obtained by different workers were tested against the experimental data. There was a significant correlation of seasonal evapotranspiration with yield that was slightly higher for dry matter than for grain. The correlation, which was quite high for linear functions, was slightly greater for nonlinear functions. The correlation was also slightly improved if evapotranspiration for different growth stages was considered rather than total seasonal evapotranspiration. Since there apears to be no single equation that fits all of the conditions studied and since different equations lead to different conclusions, it is suggested that the crop production functions considering evapotranspiration at different growth stages be used with caution. In general the degree of sensitivity of grain yield and dry matter yield to water stress for wheat cultivar WH 283 grown in field experiments under semi-arid climate decreased in the order of crop growth sub-periods I (Sowing to heading), III (Milk ripe to ripe), and II (Heading to milk ripe). However, the sensitivity of the grain yield and dry matter yield to water stress for wheat cultivar Kolibiri grown in lysimeter experiments under humid climate decreased in the order of the growth sub-periods i.e. I, II, and III.  相似文献   

18.
The amount of water used by any crop largely depends on the extent to which the soil water depletion from the root zone is being recharged by appropriate depth of irrigation. To test this hypothesis a field study was carried out in November–March of 2002–2003 and 2003–2004 on a sandy loam (Aeric haplaquept) to quantify the effect of depth of irrigation applied through micro-sprinklers on onion (Allium cepa L.) bulb yield (BY) and water use patterns. Seven irrigation treatments consisted of six amounts of sprinkler applied water relative to compensate crop (Kc) and pan (Kp) coefficient-based predicted evapotranspiration loss from crop field (ETp) (i) 160% of ETp (1.6ETp); (ii) 1.4ETp; (iii) 1.2ETp; (iv) 1.0ETp; (v) 0.8ETp; (vi) 0.6ETp; (vii) 40 mm of surface applied water whenever cumulative pan evaporation equals to 33 mm. Water use efficiency (WUE), net evapotranspiration efficiency (WUEET) and irrigation water use efficiency (WUEI) were computed. Marginal water use efficiency (MWUE) and elasticity of water productivity (EWP) of onion were calculated using the relationship between BY and measured actual evapotranspiration (ETc). Yield increased with increasing sprinkler-applied water from 0.6 to 1.4ETp. Relative to the yield obtained at 0.6ETp, yield at 1.0ETp increased by 23–25% while at 1.4ETp it was only 3–9% greater than that at 1.0ETp. In contrast, yield at 1.6ETp was 9–12% less than that at 1.4ETp. Maximum WUE (7.21 kg m−3) and WUEET (13.87 kg m−3) were obtained under 1.0ETp. However, the highest WUEI (3.83 kg m−3) was obtained with 1.2ETp. The ETc associated with the highest WUE was 20% less than that required to obtain the highest yields. This study confirmed that critical levels of ETc needed to obtain maximum BYs, or WUE, could be obtained more precisely from the knowledge of MWUE and EWP.  相似文献   

19.
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.  相似文献   

20.
Summary A field experiment was conducted on the west side of the San Joaquin Valley in California to determine water use, crop growth, yield and water use efficiency of Acala (SJ-2) cotton (Gossypium hirsutum L.) grown in 0.5 m spaced rows on a Panoche clay loam soil (Typic Torriorthents). Evapotranspiration was determined by water balance techniques utilizing neutron soil moisture measurements. All neutron measurements were made within a 3 m soil profile in 0.20 m increments. The measured evapotranspiration was compared to climatic estimates of potential evapotranspiration, and to calculations using a one-dimensional soil water balance model that separately computed soil water evaporation and plant transpiration. Crop growth was determined by weekly destructive plant sampling. Leaf area was determined along with dry matter components of leaves, stems, fruiting parts (flowers and squares) and bolls. Final yield was determined by machine harvesting (brush stripper) 720 m2 from each plot. Lint yields and fiber quality were determined by sample ginning and fiber analysis at the U.S. Cotton Research Station at Shafter, California. Three irrigation regimes were established that resulted in an evapotranspiration range from a high deficit condition to full irrigation at the calculated atmospheric demand.The measured evapotranspiration of narrow row cotton under a full irrigation regime was 778 mm, 594 mm under a limited irrigation regime and 441 mm under a regime with no post-plant irrigation. The evapotranspiration from these irrigation treatments was accurately simulated by a water balance model. that used inputs of potential evapotranspiration, leaf area index, soil water holding capacity and root development.The average lint yield from narrow row cotton with a full irrigation regime was 1583 kg/ha, the average lint yield from a limited irrigation regime was 1423 kg/ha and the average lint yield from a treatment with no postplant irrigation (fully recharged soil profile at planting) was 601 kg/ha. The full irrigation regime resulted in a dry matter production of approximately 16 t/ha while the limited irrigated regime produce 11 t/ha and the no-postplant irrigation regime produced 7 t/ha of dry matter. The fiber quality results indicated significant (0.05 level) differences only in 50% span length and micronaire, with the 2.5% span length, uniformity index, elongation and strength indicating no difference.Cotton lint yield was found to be directly related to total evapotranspiration although the relationship was slightly non-linear while dry matter yield was found to be linearly related to evapotranspiration. Both lint and dry matter yield were found to have a linear relationship to estimated transpiration from the water balance model calculations.Contribution from the Unived States Department of Agriculture, Agricultural Research Service, Western Region and the University of California  相似文献   

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