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1.
不同生育阶段受旱对旱区夏玉米生长发育和产量的影响   总被引：6，自引：3，他引：3  
2013和2014年在陕西杨凌进行田间控水试验,试验设置两个灌溉水平,每个灌溉水平下设置4种受旱处理,以全生育期均灌水为对照,分析不同生育时期受旱条件下夏玉米的株高、叶面积、生物量和产量等生理生态指标的变化特征以及蒸散量和水分利用效率的变化规律。结果表明,不同的灌水水平与受旱时段对夏玉米的产量有明显的交互作用,拔节前受旱会使最终产量偏低,且低灌水处理产量低于高灌水处理;在抽雄期受旱会明显减少穗粒数,但在同一灌水水平下产量最高;灌浆期受旱不仅明显减小了百粒重导致减产,而且蒸散量偏大,导致水分利用效率降低。因此,灌水水平较低时,应尽量避免玉米营养生长阶段(出苗和拔节)受旱;灌水水平较高时,可选择在苗期适度亏水,并避免灌浆期受旱。  相似文献   

2.
In the Southern High Plains of the U.S.A., where water for irrigation is being depleted, drought-tolerant crops are extensively grown under limited irrigation where less water is applied than is required for potential evapotranspiration and maximum yield. This study was conducted (1) to determine the effects of plant water stress at various growth stages on growth and yield of soybeans [Glycine max (L.) Merr.] and (2) to assess the adaptability of the soybean plant to limited irrigation in the stressful climate of the Southern High Plains. The 3-year study was conducted on Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll). Soybeans (‘Douglas’, indeterminate, maturity group IV) were grown with different irrigation treatments designed to subject the plants to water deficits at different growth stages. Stress initiated during R1 (early flowering) or R2 (full bloom) and extending to R3 (beginning pod development) reduced seed yields by 9–13%. But, when stress was extended to R4.5, yields were reduced by 46%. Stress beginning at R3 and extending to R4.5 reduced yields by 19%. Stress imposed at R5 and relieved at R6 reduced yields 15% in one year and 46% in a more stressful year. Stress imposed at R5 and extending to the end of the growing period (5 weeks) reduced yields by 45% in the less-stressful year and by 88% in the other. Stress throughout the last 3 weeks of the growing period (beginning at R6) reduced yields by 21 and 65%, respectively, in the two years. Water-use efficiency was not increased under limited irrigation. Soybeans are amenable to limited irrigation under the stressful climate of the Southern High Plains, but their vulnerability to drought stress during seed development complicates management. They are more suited for limited irrigation than is corn (Zea mays L.) but are less suited than are grain sorghum [Sorghum bicolor (L.) Moench], cotton (Gossypium hirsutum L.) or wheat (Triticum aestivum L.).  相似文献   

3.
《Field Crops Research》1996,48(1):47-55
Phenological development, shoot dry matter production, grain yield and yield components of rice were examined in relation to drought occurring at various stages of growth. Rice was sown three or four times at three-week intervals in the field in each of two years, and performance in three stress trials was compared with that in corresponding irrigation trials, with the aim of quantifying the response of the crop to water stress of 23–34 days' duration developing at different growth stages. When drought occurred during vegetative stages, it had only a small effect on subsequent development and grain yield. The reduction in yield of up to 30% was due to reduced panicle number per unit area in one trial, and reduced number of spikelets per panicle in another. The effect of water stress on yield was most severe when drought occurred during panicle development. Anthesis was delayed, the number of spikelets per panicle was reduced to 60% of the irrigated control and the percentage of filled grains decreased in one crop to zero. This decrease in grain yield to less than 20% of the control was associated with low dry matter production during the drought period as well as during the recovery period following the drought. When drought occurred during grain filling, the percentage of filled grains decreased to 40% and individual grain mass decreased by 20%. The effect of stress was also related to its severity during grain filling. Stress at this stage hastened maturity. The results suggest that variation in yield components due to water availability is related to the variation in dry matter production at particular growth stages. Results of a supplementary shading experiment show that the relationship between spikelet number per panicle or single grain mass and crop growth rate was the same, whether growth rate was varied by availability of soil water or solar radiation. Filled-grain percentage, however, was more sensitive to drought stress than shading when comparison was made at a similar crop growth rate.  相似文献   

4.
A field experiment was conducted during 2001-2003 to evaluate the effect of water stress on the yield and yield components of four rice cultivars commonly grown in Mazandaran province, Iran. In northern Iran irrigated lowland rice usually experiences water deficit during the growing season include of land preparation time, planting, tillering stage, flowering and grain filing period. Recently drought affected 20 of 28 provinces in Iran; with the southeastern, central and eastern parts of the country being most severely affected. The local and improved cultivars used were Tarom, Khazar, Fajr and Nemat. The different water stress conditions were water stress during vegetative, flowering and grain filling stages and well watered was the control. Water stress at vegetative stage significantly reduced plant height of all cultivars. Water stress at flowering stage had a greater grain yield reduction than water stress at other times. The reduction of grain yield largely resulted from the reduction in fertile panicle and filled grain percentage. Water deficit during vegetative, flowering and grain filling stages reduced mean grain yield by 21, 50 and 21% on average in comparison to control respectively. The yield advantage of two semidwarf varieties, Fajr and Nemat, were not maintained under drought stress. Total biomass, harvest index, plant height, filled grain, unfilled grain and 1000 grain weight were reduced under water stress in all cultivars. Water stress at vegetative stage effectively reduced total biomass due to decrease of photosynthesis rate and dry matter accumulation.  相似文献   

5.
Drought is a major factor limiting yield improvement of mung bean (Vigna radiata (L.) Wilczek) in the sub-humid, dry and intermediate zones of Sri Lanka. Therefore, the objective of this study was to analyze the yield response of mung bean to irrigation at various phenological stages in terms of radiation interception, radiation-use efficiency and harvest index. Four field experiments were carried out at two sites (Maha-Illuppallama and Kundasale) during the short, dry yala season over two years (1995 and 1996). The life cycle of mung bean was divided into three stages: 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). Eight irrigation treatments were defined as all possible combinations of irrigation during the three stages. Maximum potential soil water deficits (PSWD) ranging from 127 to 376 mm developed as a result of keeping different combinations of stages unirrigated. Maximum LAI (Lm) and the fraction of incoming radiation intercepted (F) increased significantly with the number of stages irrigated. Specifically, treatments which included irrigation during the vegetative stage achieved large Lm and F. Radiation-use efficiency (RUE), maximum total biomass (Wm), harvest index (HI) and seed yield (Y) also showed a significant positive response to the number of stages irrigated. However, all the above parameters were significantly greater in treatments which included irrigation during the pod-filling and flowering stages. The treatment which received irrigation only during the vegetative stage had significantly lower RUE, Wm, HI and Y despite having higher Lm and F. Therefore, irrigation is critical during pod-filling and flowering stages mainly because of the higher LAI during these periods and, consequently, the greater demand for water. Lack of irrigation during these critical stages resulted in the development of significant PSWD with adverse effects on photosynthesis and consequently decreased RUE. Moreover, water stress during flowering and pod-filling stages significantly reduced pod initiation and pod growth rates and thereby reduced HI. It is concluded that to maximize mung bean yields in the dry season of the sub-humid zones of Sri Lanka, irrigation should extend across all phenological stages, specially the pod-filling stage.  相似文献   

6.
System of rice intensification (SRI) is a water-saving agro-technique being popularized in Southern Asia including India. A particular key practice in SRI, reduced water application (no continuous flooding), needs to be more farmer-friendly for its mass adoption under traditional and non-traditional cultivation. A field experiment was conducted maintaining different water regimes throughout the crop season (vegetative as well as reproductive stages) by scheduling irrigation applications at 1, 3, or 5 days after disappearance of ponded water (DADPW), using two different plant spacings and two different varieties. With an increase in the period of water stress, tiller production was increased significantly (P ≤ 0.05) and found to be maximum under prolonged stress, i.e., 5 days after disappearance of ponded water (5 DADPW). Increased tiller production did not result in yield increments, but yield-contributing parameters (panicle weight, grain weight per panicle, filled grain percentage, and test weight) were confirmed as critical determinants of yield. Plant nutrient (NPK) uptake was reduced under stress conditions, but the translocation of phosphorus and potassium from sources to sink was increased significantly in this study. Nutrient utilization efficiency was also enhanced under mild (3 DADPW) to prolonged (5 DADPW) water stress conditions. No significant reduction in yield was recorded under mild water stress, and this resulted in increased water productivity; however, significant yield loss was observed under prolonged water stress (5 DADPW).  相似文献   

7.
不同密度下施氮对甜玉米果穗形成的影响   总被引：3，自引：0，他引：3  
以甜玉米甜单8号为材料,在不同种植密度(45 000、60 000和75 000株/hm2)及不同供氮水平(0、120和240 kg/hm2)下对果穗产量、穗粒结构、穗部性状形成过程及子粒灌浆动态进行了研究。结果表明：施氮水平、种植密度对甜玉米产量影响显著,施氮可显著提高鲜穗产量与子粒产量;穗长、穗粗的形成贯穿整个果穗发育过程,可用Logistic曲线拟合,分别在吐丝与抽雄期达到最终穗长与穗粗的50%;穗粒数在抽雄期达到最高峰,随时间推进果穗败育粒增加;施氮对单穗重的提高在高密度下最明显。施氮能够促进玉米子粒的灌浆,但不同密度下施氮对灌浆动态的影响明显不同,在4～20 DAP子粒体积、百粒鲜重、灌浆速率均明显升高,且施氮处理高于不施氮处理。  相似文献   

8.
《Field Crops Research》1987,16(3):231-241
Chickpeas (Cicer arietinum L., cv H-355) were subjected to four irrigation treatments after crop establishment: (i) unirrigated (D); (ii) irrigated until flower initiation [85 days from sowing (DAS)] and unirrigated thereafter (WD); (iii) unirrigated until active seed setting (129 DAS) and irrigated thereafter (DW); (iv) irrigated throughout (W). Several plant processes were measured on clear days betweem 85 and 144 DAS. The unirrigated plants had lower leaf water potentials, canopy evapotranspiration rates (ET), canopy photosynthetic rates (PN), plant dry weight and grain yield compared to the irrigated plants, but increased canopy-air temperature differences (Tc−Ta). Cessation of irrigation at flowering induced a rapid decrease in canopy photosynthesis and reduced the grain yield by 33% due to a decrease in the number of pods set. Irrigation from 129 DAS resulted in some recovery of grain yield resulting from the development of a small number of late pods with small seeds. Among yield components, water stress primarily affected the number of pods per plant and had little effect on the grain number per pod. Grain yield was linearly related to pod number, leaf water potential, and mean PN.  相似文献   

9.
《Plant Production Science》2013,16(5):592-600
Abstract

This research was conducted to determine the yield and water-use efficiency of maize under fixed and variable alternate furrow irrigation (fixed AFI, variable AFI) and every furrow irrigation (EFI) at different irrigation intervals in areas with shallow and deep groundwater. In variable AFI, water was applied to the furrow, which was dry in the previous irrigation cycle. The results indicated that even at 4-day irrigation intervals the water needs of maize on a fine textured soil in both areas (with deep and shallow water table) are not met by AFI. The decrease in grain yield due to water stress was mainly due to the decrease in the number of grains per cob and to a lesser extent to the decrease in 1000-grain weight. At the Kooshkak site with shallow groundwater (between 1.31 and 1.67 m), grain yields in AFI at 4- and 7-day intervals were comparable to those obtained in EFI at 7- and 10-day intervals, respectively. This might be due to the contribution of groundwater to the water use of the plant (about 5-10%). In the Badjgah area, with deep water depth, grain yield in AFI at 7-day intervals was statistically lower than that obtained in EFI at 10-day interval. In AFI, a shorter irrigation interval (4-day) may alleviate the water stress and result in no yield reduction compared with that in EFI at 7-day intervals even though water application was reduced. Furthermore, in the area with a shallow water table, AFI at 7-day intervals may be superior to EFI at 10-day irrigation intervals. When seasonal irrigation water is less than 700 mm, it may be preferable to use AFI at 10-day intervals to increase water-use efficiency, especially in areas with shallow groundwater. In general, when water was insufficient for full irrigation, the relative grain yield (yield per unit water applied) of maize under AFI was higher than those under EFI.  相似文献   

10.
Under dryland conditions of the Texas High Plains, maize (Zea mays) production is limited by sparse and erratic precipitation that results in severe water stress particularly during grain formation. When plant populations are reduced to 2.0–3.0 plants m−2 to conserve soil water for use during grain filling, tillers often form during the vegetative growth and negate the expected economic benefit. We hypothesized that growing maize in clumps spaced 1.0 m apart would reduce tiller formation, increase mutual shading among the plants, and conserve soil water for grain filling that would result in higher grain yield. Studies were conducted during 2006 and 2007 at Bushland, TX. with two planting geometries (clump vs. equidistant), two irrigation methods (low-energy precision applicator, LEPA, and low-elevation spray applicator, LESA) at three irrigation levels (dryland, 75 mm and 125 mm in 2006; and dryland, 50 mm and 100 mm in 2007). For dryland plots in 2007, clump plants had only 0.17 tillers (0.66 tillers m−2) compared with 1.56 tillers per plant (6.08 tillers m−2) for equidistant spacing. Tillers accounted for 10% of the stover for the equidistant plants, but less than 3% of the grain. Clump planting produced significantly greater grain yields (321 g m−2 vs. 225 g m−2 and 454 g m−2 vs. 292 g m−2 during 2006 and 2007, respectively) and Harvest Indexes (0.54 vs. 0.49 and 0.52 vs. 0.39 during 2006 and 2007, respectively) compared with equidistant plants in dryland conditions. Water use efficiency (WUE) measurements in 2007 indicated that clumps had a lower evapotranspiration (ET) threshold for initiating grain production, but the production function slopes were 2.5 kg m−3 for equidistant treatments compared to 2.0 kg m−3 for clump treatments. There was no yield difference for method of irrigation on water use efficiency. Our results suggest that growing maize in clumps compared with equidistant spacing reduced the number of tillers, early vegetative growth, and Leaf Area Index (LAI) so that more soil water was available during the grain filling stage. This may be a useful strategy for growing maize with low plant populations in dryland areas where severe water stress is common.  相似文献   

11.
The green belly stink bug, Dichelops furcatus (F.) (Hemiptera: Heteroptera: Pentatomidae) is a pest of corn and soybean in southern Brazil. It also occurs on wheat, but information on its damage to this crop is limited. To determine the need for sustainable IPM programs, the impact of this bug on wheat production should be determined. Studies were conducted in the screenhouse with 1, 2 and 4 bugs caged for 16 days on single plants, cv. ‘BRS Parrudo’. During the vegetative period (plants ca. 25 cm tall), all infestation levels significantly reduced plant height and ear head length, but did not reduce grain yield. Feeding damage caused tissue necrosis on leaves. During the booting stage, grain yield was significantly reduced with 2 and 4 bugs per plant; ear heads were small, discolored and abnormally developed. In 2013 and 2014 field trials, plants were infested for 18 days with 2, 4 and 8 bugs per m2 at vegetative, booting, and milky grain stage. At these infestation levels, there was no significant reduction in grain yield. There was a significant decrease in the number of normal seedlings resulting from seeds exposed to 8 bugs per m2 at the milky grain stage. Results suggest that, in general, there is no need to control D. furcatus on wheat, unless numbers are ≥8 bugs per m2 during reproductive period.  相似文献   

12.
Sorghum [Sorghum bicolor (L.) Moench] is a C4 cereal grain crop grown primarily in arid and semi-arid regions in the world with limited or no irrigation. Sorghum production fluctuates and largely depends on the amount and distribution of rainfall. Transpiration efficiency (TE), the biomass produced per unit water transpired, could be a potential trait to improve sorghum yield in areas where irrigation is limited. We have developed a mini-lysimetric method that directly measures whole plant TE in sorghum during an early vegetative stage under greenhouse conditions. The method was evaluated with 11 inbred lines and three hybrids under two greenhouse environments. In general, TE determined with the gravimetric method was higher under lower vapor pressure deficit conditions; however, similar rankings in TE were obtained across the experiments. The method described in this report offers a simple, high-throughput, and affordable way to determine the integrated TE in sorghum at an early vegetative stage.  相似文献   

13.
水氮胁迫对玉米产量和氮素吸收和运移的影响   总被引：2，自引：0，他引：2  
2011~2012年在吉林公主岭试验区可移动防雨棚内进行两年微区试验,探讨水氮胁迫对玉米产量及氮素的吸收和分配的影响。结果表明,全生育期灌水300 mm情况下,玉米产量随施氮量的增加而增加;水分胁迫(灌水100 mm)情况下,玉米产量随施氮量的增加而减少。植株氮积累总量成熟期最高,氮素在营养器官中的比例最高时期是拔节期,生殖器官含氮比例最高在吐丝期,子粒的含氮百分比最高时期是吐丝后15 d。水氮胁迫条件下,氮素转运率、贡献率均下降,仅氮胁迫转运率和贡献率增加。相同灌水量情况下,子粒吸收氮素量与施氮量显著正相关;水分胁迫条件下,表观土壤水分利用效率随施氮量的增加而下降,正常供水则相反;水分胁迫下的土壤水分利用效率极显著高于正常供水。  相似文献   

14.
Jones RS  Mitchell CA 《Crop science》1992,32(2):404-408
Agronomic and horticultural crop species experience reductions in growth and harvestable yield after exposure to physical agitation (also known as mechanical stress), as by wind or rain. A greenhouse study was conducted to test the influence of mechanical stress on soybean yield and to determine if exposure to mechanical stress during discrete growth periods has differential effects on seed yield. A modified rotatory shaker was used to apply seismic (i.e., shaking) stress. Brief, periodic episodes of seismic stress reduced stem length, total seed dry weight, and seed number of soybean [Glycine max (L.) Merr.]. Lodging resistance was greater for plants stressed during vegetative growth or throughout vegetative and reproductive growth than during reproductive growth only. Seed dry weight yield was reduced regardless of the timing or duration of stress application, but was lowest when applied during reproductive development. Seismic stress applied during reproductive growth stages R1 to R2 (Days 3 to 4) was as detrimental to seed dry weight accumulation as was stress applied during growth stages R1 to R6 (Days 39 to 42). Seed dry weight per plant was highly correlated with seed number per plant, and seed number was correlated with the seed number of two- and three-seeded pods. Dry weight per 100 seeds was unaffected by seismic-stress treatment. Growth and yield reductions resulting from treatments applied only during the vegetative stage imply that long-term mechanical effects were induced, from which the plants did not fully recover. It is unclear which yield-controlling physiological processes were affected by mechanical stress. Both transient and long-term effects on yield-controlling processes remain to be elucidated.  相似文献   

15.
Aloe vera (Sábila) is used in folklore medicine and commercial cosmetology products in many countries. Little is known about the plant's physiological, growth, and yield responses under different irrigation regimes. The plant has a crassulacean acid metabolism (CAM) that allows water conservation within the tissue, and therefore, resistance to high water stress. A. vera plants were submitted to different irrigation regimes in a greenhouse experiment to evaluate the response of the physiologic processes such as stomatal resistance and transpiration as well as leaf growth and yield. The experiment consisted of three irrigation regimes under a completely randomized design. No initial effect on stomatal resistance or transpiration was exhibited, but as time elapsed changes in these variables were noted. We suggest that the high water content in the parenchyma maintains stomatal opening despite water stress. In a subsequent period, the leaves that were submitted to water stress at the beginning, showed stomatal opening reduction related to low soil water potential. The low soil water potential reduced leaf weight, plant growth rate, and leaf number, mainly in leaf growth during the experiment confirming the sensitivity of new leaves to water stress. The results suggest that the low leaf temperature increases stomatal resistance, decreases plant and leaf growth rates. This behavior is opposite to other CAM species in semiarid condition.  相似文献   

16.
A field experiment was conducted during summer season of 2005 at the Research Station (altitude 180 m above sea level, 41 degrees 21' N and 36 degrees 15'E) Faculty of Agriculture, Ondokuz Mayis University, Samsun, Turkey. Experiment consisted of three irrigation levels and a non-irrigation level. Drip irrigation treatments consisted of three soil water deficits in the 90 cm soil profile depth was replenished to field capacity. Irrigation treatments were A: no irrigation, B: irrigation at 50% of available soil water capacity, C: irrigation at 30% of available soil water capacity, D: irrigation at 15% of available soil water capacity. The average seasonal water use values ranged from 257.14 to 285.71 mm in corn treatments. Irrigation frequencies (intervals) significantly affected corn crop yields. The average corn grain yields varied from 7.98 to 29.16 t ha(-1). The treatment D was recorded significantly higher corn grain yield 29.16 t ha(-1) compared to B (21.59 t ha(-1)); C (19.15 t ha(-1)) and A (7.98 t ha(-1)), respectively. According to research results, the maximum corn grain yield was obtained when the corn plants were irrigated at 15% of available soil water capacity to field capacity.  相似文献   

17.
Lesquerella fendleri (Gray) Wats. is a potential new oilseed crop for the arid southwestern United States. Lesquerella seed oil with similar properties as castor oil is being considered as a domestic replacement for the imported castor oil. Development of new crops with low irrigation needs is of high priority. Because the most critical stage of sensitivity to moisture deficits has not been determined in Lesquerella species, the objectives of this study were: (i) to identify the most critical stage or stages for moisture deficit and, (ii) to determine the effect of moisture deficit on yield, yield components, oil and fatty acid composition. Two-year field studies were conducted at the New Mexico State University, Leyendecker Plant Science Research Center. The experimental design was a randomized complete block. The treatments consisted of (a) T1: Continuous favorable soil moisture [irrigated at 50% soil water depletion (SWD)]. (b) T2: Moisture stress (75% SWD) from establishment to initial flowering with no stress from flowering to final harvest (50% SWD). (c) T3: No stress imposed from establishment to initial flowering (50% SWD) followed by stress to final harvest (75% SWD). (d) T4: Moisture stress (75% SWD) from establishment to final harvest. The amount of water applied ranged from 810 to 729 mm for the first year, and 810 to 625 mm for the second year. Seed weight per plant and number of pods per plant were generally higher when water availability was maintained at or above 50% SWD throughout the growing season. Neither seed number per pod nor seed size was influenced by irrigation treatments. Lesquerella was more sensitive to water availability during flowering and seed development as a greater loss in seed yield occurred when irrigation was delayed to 75% SWD during that stage of development. Seed yield and dry matter production from the 2 year field studies were closely related to the seasonal cumulative evapotranspiration. For each millimeter of evapotranspiration, seed yield increased from 1.8 kg ha−1 mm in 1994–1995 to 1.3 kg ha−1 mm for 1995–1996. The dry matter production increased 13.4 kg ha−1 for each mm increase in seasonal evapotranspiration during 1994–1995. This relationship was a second order polynomial with an R2 of 0.86 during 1995–1996. The WUEgr and WUEdm were highest under the most favorable water availability conditions for growth and seed development. Delaying irrigation to 75% SWD throughout the crop growth period resulted in the lowest oil content. Lesquerolic acid content was not affected by irrigation during both the growing seasons.  相似文献   

18.
Barley grain yield in rainfed Mediterranean regions can be largely influenced by terminal drought events. In this study the ecophysiological performance of the ‘Nure’ (winter) × ‘Tremois’ (spring) barley mapping population (118 Doubled Haploids, DHs) was evaluated in a multi-environment trial of eighteen site–year combinations across the Mediterranean Basin during two consecutive harvest years (2004 and 2005). Mean grain yield of sites ranged from 0.07 to 5.43 t ha−1, clearly dependent upon both the total water input (rainfall plus irrigation) and the water stress index (WSI) accumulated during the growing season. All DHs were characterized for possessing molecular marker alleles tagging four genes that regulate barley cycle, i.e. Vrn-H1, Vrn-H2, Ppd-H2 and Eam6. Grain yield differences were initially interpreted in terms of mean differences between genotypes (G), environments (E), and for each combination of genotype and environment (GE) through a “full interaction” ANOVA model. Variance components estimates clearly showed the greater importance of GE over G, although both were much lower than E. Alternative linear and bilinear models of increasing complexity were used to describe GE. A linear model fitting allelic variation at the four genes explained genotype main effect and genotype × environment interaction much better than growth habit itself. Adaptation was primarily driven by the allelic constitution at three out of the four segregating major genes, i.e. Vrn-H1, Ppd-H2 and Eam6. In fact, the three genes together explained 47.2% of G and 26.3% of GE sum of squares. Grain yield performance was more determined by the number of grains per unit area than by the grain weight (phenotypic correlation across all genotypic values: r = 0.948 and 0.559, respectively). The inter-relationships among a series of characters defining grain yield and its components were also explored as a function of the length of the different barley developmental phases, i.e. vegetative, reproductive, and grain filling stages. In most environments, the best performing (adapted) genotypes were those with faster development until early occurrence of anthesis. This confirmed the crucial role of the period defining the number of grains per unit area in grain yield determination under Mediterranean environments.  相似文献   

19.
Productivity and resource-use efficiency in corn (Zea mays L.) are crucial issues in sustainable agriculture, especially in high-demand resource crops such as corn. The aims of this research were to compare irrigation scheduling and nitrogen fertilization rates in corn, evaluating yield, water (WUE), irrigation water (IRRWUE) and nitrogen use (NUE) efficiencies. A 2-year field experiment was carried out in a Mediterranean coastal area of Central Italy (175 mm of rainfall in the corn-growing period) and corn was subjected to three irrigation levels (rainfed and supply at 50 and 100% of crop evapotranspiration, ETc) in interaction with three nitrogen fertilization levels (not fertilized, 15 and 30 g (N) m−2). The results indicated a large yearly variability, mainly due to a rainfall event at the silking stage in the first year; a significant irrigation effect was observed for all the variables under study, except for plant population. Nitrogen rates affected grain yield plant−1 and ear−1, grain and biomass yield, HI, WUE, IRRWUE and NUE, with significant differences between non-fertilized and the two fertilized treatments (15 and 30 g (N) m−2). Furthermore, deficit irrigation (50% of ETc) was to a large degree equal to 100% of the ETc irrigation regime. A significant interaction “N × I” was observed for grain yield and WUE. The effect of nitrogen availability was amplified at the maximum irrigation water regime. The relationships between grain yield and evapotranspiration showed basal ET, the amount necessary to start producing grain, of about 63 mm in the first and 206 mm in the second year. Rainfed crop depleted most of the water in the 0–0.6 m soil depth range, while irrigated scenarios absorbed soil water within the profile to a depth of 1.0 m. Corn in a Mediterranean area can be cultivated with acceptable yields while saving irrigation water and reducing nitrogen supply and also exploiting the positive interaction between these two factors, so maximizing resource-use efficiency.  相似文献   

20.
《Field Crops Research》2002,73(2-3):181-200
A series of experiments were conducted in drought-prone northeast Thailand to examine the magnitude of yield responses of diverse genotypes to drought stress environments and to identify traits that may confer drought resistance to rainfed lowland rice. One hundred and twenty eight genotypes were grown under non-stress and four different types of drought stress conditions.Under severe drought conditions, the maintenance of PWP of genotypes played a significant role in determining final grain yield. Because of their smaller plant size (lower total dry matter at anthesis) genotypes that extracted less soil water during the early stages of the drought period, tended to maintain higher PWP and had a higher fertile panicle percentage, filled grain percentage and final grain yield than other genotypes. PWP was correlated with delay in flowering (r=−0.387) indicating that the latter could be used as a measure of water potential under stress. Genotypes with well-developed root systems extracted water too rapidly and experienced severe water stress at flowering. RPR which showed smaller coefficient of variation was more useful than root mass density in identifying genotypes with large root system.Under less severe and prolonged drought conditions, genotypes that could achieve higher plant dry matter at anthesis were desirable. They had less delay in flowering, higher grain yield and higher drought response index, indicating the importance of ability to grow during the prolonged stress period.Other shoot characters (osmotic potential, leaf temperature, leaf rolling, leaf death) had little effect on grain yield under different drought conditions. This was associated with a lack of genetic variation and difficulty in estimating trait values precisely.Under mild stress conditions (yield loss less than 50%), there was no significant relationship between the measured drought characters and grain yield. Under these mild drought conditions, yield is determined more by yield potential and phenotype than by drought resistant mechanisms per se.  相似文献   

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