Plant water deficit effects on Aroostook County potato yields over 30 years 1

We estimated potential irrigation requirements for potato production in Aroostook County, Maine. These requirements were computed from a Plant Water Deficit (PWD) index based on readily available streamflow and climatic parameters. Actual evapotranspiration (AET) figures for specified time periods were assumed to equal the differences between rainfall and runoff. Runoff was computed from differences between streamflow and baseflow for the Aroostook River. Potential evapotranspiration (PET) was computed by the Thomthwaite method. The PWD was established as the difference between PET and AET. The yearly PWD index was then equal to the accumulation of 5-day average values for the PET-AET for each of 30 years of data. Similar computations were made for 10-and 20-day intervals. A yearly temperature index based on Growing Degree Day (GDD) units was also computed. Potato yields were then compared to PWD and GDD values. Results show PWD figures ranging from 11.74 cm to 25.78 cm. There was a highly significant negative correlation existing between PWD and potato yield.     

The effect of water stress in regulated deficit irrigation on soybean yield (Glycine max [L.] Merr.)

The objective of this research was to investigate the effect of water stress in regulated deficit irrigation (RDI) on the yield of soybean growing on Ultisol soil. This research was conducted under plastic house on the experimental farm of Lampung Polytechnique from August to November 2004. The water stress treatments in regulated deficit irrigation were ET₁ (1.0 × ET_c), ET₂ (0.8 × ET_c), ET₃ (0.6 × ET_c), ET₄ (0.4 × ET_c) and ET₅ (0.2 × ET_c), arranged in a randomized block design with four replications. ET_c means crop evapotranspiration under standard condition, which was well watered. For example, the ET₂ (0.8 × ET_c) treatment means that the amount of supplied water per a day is the same as the crop adjustment evapotranspiration (ET_cadj) with the value 0.8 of water stress coefficient (K _s). The RDI treatments were carried out just at vegetative phase and its treatments were stopped at the beginning of flowering phase, and afterwards the treatments were watered at 1.0 × ET_c. The results showed that since week II, the soybean experienced stress throughout the growth period except ET₂ treatment. ET₂ treatment started to be stressed at week V and continued to be stressed until the harvest time. At the ET₃ treatment, the critical water content (θ_c) of soybean was reached at week II, and the θ_c was 0.24 m³/m³ on the average. The RDI at vegetative period significantly affected the yield. The highest yield was ET₁ (35.2 g/plant), followed by ET₂ (31.0 g/plant), ET₃ (18.1 g/plant), ET₄ (7.6 g/plant), and ET₅ (3.3 g/plant). The optimal water management of soybean with the highest yield efficiency was regulated deficit irrigation with water stress coefficient (K _s) of 0.80 for vegetative phase.     

Yield response of corn to irrigation and nitrogen fertilization in a Mediterranean environment

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.     

Potato growth with and without plastic mulch in two typical regions of Northern China

Plastic film mulching is an important agricultural practice to save water and improve crop productivity in Northern China. Three field experiments were conducted to examine the effect of plastic mulch on soil temperature, potato (Solanum tuberosum L.) growth and evapotranspiration under drip irrigation in two typical regions of Northern China in 2001 and 2006. Results suggest that daily mean soil temperature under mulch was 2–9 °C higher than without mulch, especially during the early growth. Potato growth was restrained under mulching conditions in the North China Plain mainly due to the higher air temperature in this region and thus the higher soil temperature. The negative effects of mulching included a lower emergence and fewer marketable tubers per plant. Evapotranspiration and potato tuber yield were both reduced by mulch, especially in the North China Plain. In northwest China, mulch favorably increased the weight of jumbo tubers (W ≥ 300 g) per plant. Mulching duration had little effect on potato evapotranspiration in northwest China. However, both tuber yield and water use efficiency (WUE) decreased with increases in mulch duration, which suggests the plastic mulch should be removed early.     

Growth,water use,and kernel abortion of maize subjected to drought at silking

Maize (Zea mays L.) grain yield is particularly sensitive to water deficits that coincide with the tasseling-silking period, causing marked reductions in grain number. More knowledge about crop responses to water supply is required, however, to explain the causes of kernel number reductions under the mild stresses characteristic of humid regions. The objectives of this study were to: (i) quantify crop evapotranspiration, E_c, and its relationship with shoot biomass production, grain yield, and kernel number; and (ii) determine the impact on final kernel number of supplying fresh pollen to silks whose appearance is delayed by water deficits at silking. Field experiments were conducted at Balcarce (37°45′S, 130 m) during 1988/89 and 1989/90 with two sowing dates (6 weeks apart) to provide differences in evaporative demand. Plastic covers were placed on the ground of water-deficit plots to generate a 40-day period of lowered water supply bracketing silking. Control plots received rain plus additional furrow irrigation in order to keep the ratio between crop (_c) and potential (E_p) Penman evapotranspiration greater than 0.9. Plant water status indicators revealed differences between treatments, but failed to reflect soil water status. Water deficit reduced plant height, maximum leaf area index, and shoot biomass. Shoot biomass accumulation was correlated with E_c, but higher water-use efficiencies (WUE) were found for the water-stress treatments. Grain yield was correlated to kernels m⁻² (r = 0.88; 6 d.f.), and both grain yield and kernels m⁻² were related to E_c during the treatment period, resulting in reductions of 4.7 grains m⁻² and 17.7 kg ha⁻¹ for each mm reduction in E_c. The number of kernels per ear did not improve when fresh pollen was applied to late appearing silks, suggesting that ovaries which failed to expose their silks synchronously with pollen shedding were deleteriously affected by water stress.     

Yield, water use efficiency and nitrogen uptake in potato: influence of drought stress

Summary A lysimeter experiment was performed to study the optimal allocation of limited water supply in potatoes. Irrigation regimes equal to 40, 60 and 80% of maximum evapotranspiration (ET) were evenly applied over the crop cycle. Other treatments involved withholding 80 mm of irrigation, based on ET, beginning at each of three designated growth stages (tuber initiation, early and late tuber growth). An irrigated control treatment, restoring the entire ET, was included for comparison. Continuous drought stress reduced photosynthesis as irrigation volumes were reduced. Plant biomass and tuber yield decreased almost proportionally to water consumption, so that WUE was roughly constant. N uptake was highest in the control and in 80% ET treatment. Withholding water during tuberisation severely hindered plant physiological processes and penalized tuber yield. Reductions in photosynthesis, total biomass and yield were the greatest when drought was imposed during tuber initiation. The earliest stress resulted in the lowest WUE and N uptake. A new crop water stress index (SI) was proposed, which combines atmospheric demand for water and canopy temperature.     

Physiological Parameters,Harvest Index and Yield of Deficient Irrigated Cotton

Summary

The agronomic and physiological response of cotton to deficient irrigation as well as its influence on yield quality was determined. Plant growth expressed as plant height and accumulation of fresh weight was significantly affected by water deficit. Nevertheless, neither seed cotton yield nor lint quality were decreased. Turgor pressure was maintained positive for the entire growth cycle. The relationship between growth and yield parameters is discussed.     

花后水分亏缺对夏玉米产量及水分利用效率的影响

以郑单958为试验材料,分别于吐丝至吐丝15 d、吐丝至吐丝30 d和吐丝30 d至成熟期3个时期进行水分亏缺处理(T1、T2、T3),以花后适宜水分供应为对照(CK),研究花后不同时期水分亏缺对夏玉米产量和水分利用效率的影响。结果表明,3个阶段的水分亏缺均使玉米产量降低,其中,T1处理的降幅最大,T3处理的降幅最小,与CK相比均达到显著性差异。T1处理下玉米的叶片衰老最快,在整个生育后期叶面积指数一直处于较低的水平;成熟期时,各处理的叶面积指数均低于CK。T1和T2处理使成熟期时的单株总干重显著下降,较CK分别下降了24.98%、29.94%。T3处理下作物的水分利用效率最高,比CK高0.5 kg/(mm·hm2);T1处理下作物的水分利用效率最低,且与CK达到显著差异。各个时期的水分胁迫均使玉米的穗粒数减少,穗长变短,穗粗降低,行粒数减少,秃尖变长,空秆率上升。     

Irrigation and soil temperature effects on Russet Burbank quality

Potato growers in the Pacific Northwest suffer large economic losses in seasons with above normal temperatures, due to excess reducing sugars in tubers, which cause dark-end French fries. Our objective was to study irrigation management effects on potato quality, particularly the factors causing dark-end French fries or sugar-end syndrome. Solid-set sprinkler irrigated plots were established on potatoes at Kimberly, Idaho during the 1987, 1988 and 1989 irrigation seasons, and at Parma, Idaho in 1987 and 1988. Irrigation treatments were high and low frequency (3/week and I/week) and two or three water application amounts referenced to estimated evapotranspiration (ET, ET+20%, and ET-20%). Neither frequency nor amount significantly affected yields. Irrigation frequency had more influence on potato quality than application amount. More frequent irrigation produced slightly higher quality tubers and lower incidence of dark-ends when fried. Soil temperature was inversely related to tuber grade quality and directly related to percentage of sugar-end tubers. Soil temperature was about 0.5 C lower under the high frequency than under the low frequency irrigation regime. On these silt loam soils, allowing available soil water to decline to 50 percent had no adverse affect on yield or quality.     

Influence of vine senescence and storage on wound healing of Russet Burbank tubers

Potato (Solanum tuberosum L. cv. Russet Burbank) tubers were harvested weekly over a 6 week period from non-water-stressed and water-stressed plants. Discs were cut from fresh tubers and from tubers stored for 10 days at 4°C to determine their wound healing ability as evaluated by disc resistance to water loss. Neither harvest date nor water status significantly influenced wound healing while storage significantly increased wound healing ability. Enhanced wound healing associated with storage was accompanied by reduced variability of disc resistance to water loss and increased levels of suberin as reflected by the diol and alcohol components. This work suggests that plant senescence and harvest date are not good indicators of the potential wound healing ability of tubers. Physiological evidence is presented to support the practice of short periods of storage following harvest to improve tuber wound healing ability and thereby reduce shipping and handling losses due to injury.     

Benchmarking sunflower water productivity in semiarid environments

Appropriate benchmarking is essential for evaluating the efficiency with which crops use water and for identifying constraints, other than water, to crop yield. No benchmark exists for sunflower. Boundary and simulation analyses were used to quantify the water productivity of sunflower crops grown in the Western Pampas (semiarid central Argentina). The approach involved the use of a large database (n = 169) collected in farmers’ fields over a period of 4 years, and the application of a crop simulation model in combination with actual weather and soil data. Using field data, an upper bound of 8 kg grain ha⁻¹ mm⁻¹ for water productivity, with an apparent seasonal soil evaporation of 75 mm, was defined. Seasonal water supply exceeded maximum expected seasonal crop requirements (ca. 630 mm) for many crops, and a majority of crops with <630 mm of available water during the season had water productivities considerably lower than the upper bound. The field data-based upper bound was indistinguishable from that obtained using yields for a set of 47 simulations using observed initial values for soil water and nitrogen profiles. Simulation confirmed the main features of the boundary-analysis applied to field data, and many simulated crops had yields that fell below the boundary function, even when simulated yield was plotted against simulated seasonal evapotranspiration or transpiration. Long-term (33-year) simulation analyses for two sites showed that most sunflower crops in the area are subjected to episodes of transient and unavoidable water stress after floral initiation. High levels of available soil water at sowing moderate, but in most years do not eliminate, these exposures to water stress. Yield gaps with respect to the boundary function were associated with deficient or excessive rainfall during grain filling, and other, non-water related, factors such as inadequate crop nutrition, biotic stresses, low photothermal quotients during the interval close to anthesis, and lodging. A grain yield/seasonal evapotranspiration plot for a large (n = 154) data set from experiments conducted by others in five separate environments suggests that the boundary function found for the Western Pampas is broadly applicable. Sunflower water productivity, corrected for oil-synthesis costs and seasonal vapour pressure deficit differences, approximates that of winter cereals grown in Mediterranean environments.     

不同时期干旱和干旱程度对夏玉米生长发育及耗水特性的影响

通过防雨棚下测坑试验,研究不同生育期干旱,设轻度干旱和重度干旱对夏玉米生长状况、耗水规律、产量以及水分利用效率的影响。结果表明,不同生育期干旱均会抑制植株株高和叶面积指数增长,受旱越重,株高和叶面积指数越小。适宜水分处理的植株株高与叶面积长势优于其他处理;与适宜水分处理相比,随着干旱时期的后移,产量呈先降后升的趋势,其中,苗期轻度干旱的处理减产最少,为9.88%,抽雄期重度干旱穗粒数最少,为349.98粒,减产最多,达32.67%;夏玉米拔节期重度干旱处理的耗水量最低,为258.09 mm,任何生育阶段受旱,其日耗水量随着干旱程度的加重而降低。对各处理产量和耗水量进行分析,两者呈良好的二次曲线关系,拔节期轻度干旱处理的水分利用效率(WUE)最高,为2.202 kg/m3,其次是苗期重度干旱的处理,后期干旱处理由于减产幅度超过节水的幅度,WUE降低。通过对各处理的产量和WUE综合分析,确定了夏玉米节水高产的灌溉控制指标。     

水分胁迫对水稻腾发量及产量的影响

采用盆栽与蒸渗仪栽培平行进行的方法,研究了水分胁迫对水稻形态、腾发量及产量的影响,结果表明:水稻分蘖期遭受胁迫使其分蘖数显著减少,叶面积指数明显减小,轻度胁迫日腾发量比对照平均降低0.82 mm,中度胁迫平均降低2.26 mm,重度胁迫平均降低3.43 mm。拔节孕穗期遭受水分胁迫在单阶段胁迫中减产幅度最大。多阶段连续轻度水分胁迫,对水稻分蘖、叶面积指数及产量的影响极为显著,影响程度超过任一时段单阶段重度水分胁迫。     

Root size,distribution and soil water depletion as affected by cultivars and environmental factors

Field experiments were carried out in two parts at the Luancheng Experimental Station in the North China Plain. Part I, which was a continuous experiment that ran from 1990 to 2008, investigated the change of grain yield, evapotranspiration (ET), root size and soil water utilization of winter wheat (Triticum aestivum L.) under three water regimes (rain-fed, two and four irrigation applications). Part II used 10 cultivars released from 1970 to 2000 that were grown under the same condition for two seasons (2005/2006 and 2006/2007) to compare root size, root:shoot ratio and soil water depletion (SWD). The results of testing in Part I showed that the yield and ET of winter wheat gradually increased from 1990 to the present. There was no consistent change in total root length (TRL) over time. The difference in root size among seasons and irrigation treatments mainly occurred in the upper soil profile, where the root length density (RLD) was greater. No direct relationship was found between root size and soil water use. Thus, TRL was not a factor that indicated the water extracting capacity of crops. The results from Part II revealed that the seasonal ET of earlier released cultivars (ERC) was similar to that of recently released cultivars (RRC) under well-watered conditions. However, ET was slightly increased from ERC to RRC under water deficit conditions, indicating high soil water depletion by RRC. TRL decreased from ERC to RRC and was significantly correlated with plant height. The breeding of winter wheat that reduced plant height not only increased harvest index, but also reduced root size, resulting in a smaller root:shoot ratio. The reduction in TRL from ERC to RRC mainly occurred in the top soil profile. The results from both tests indicate that TRL is not a factor that determines soil water use; rather, the distribution of RLD along the soil profile plays more important role in soil water utilization. Smaller root size in the upper soil layer did not affect soil water uptake, and might be more economical in terms of production efficiency.     

Modelling the nitrogen-driven trade-off between nitrogen utilisation efficiency and water use efficiency of wheat in eastern Australia

The nitrogen-driven trade-off between nitrogen utilisation efficiency (yield per unit nitrogen uptake) and water use efficiency (yield per unit evapotranspiration) is widespread and results from well established, multiple effects of nitrogen availability on the water, carbon and nitrogen economy of crops. Here we used a crop model (APSIM) to simulate the yield, evapotranspiration, soil evaporation and nitrogen uptake of wheat, and analysed yield responses to water, nitrogen and climate using a framework analogous to the rate-duration model of determinate growth. The relationship between modelled grain yield (Y) and evapotranspiration (ET) was fitted to a linear-plateau function to derive three parameters: maximum yield (Y_max), the ET break-point when yield reaches its maximum (ET^#), and the rate of yield response in the linear phase (ΔY/ΔET). Against this framework, we tested the hypothesis that nitrogen deficit reduces maximum yield by reducing both the rate (ΔY/ΔET) and the range of yield response to evapotranspiration, i.e. ET^# − E_s, where E_s is modelled median soil evaporation.     

不同水分处理对春玉米生态指标、耗水量及产量的影响

以春玉米为试验材料,通过防雨棚测坑种植,人工严格控制设置不同的土壤水分处理,研究不同水分处理对玉米植株生态指标、耗水量和产量的影响。结果表明,水分胁迫抑制了玉米的生长发育,高水分处理均具有较高的叶面积、株高及茎粗;轻度胁迫对各项指标影响不大,随着胁迫的进一步加深,各项生态指标均呈下降趋势;低水分处理产量明显降低,耗水量较小,后期植株衰老加速,成熟期提前;高水分处理存在奢侈性蒸腾蒸发,耗水量最高,产量低于轻度胁迫处理。通过产量与耗水量对比分析,确定当地春玉米适宜土壤水分指标控制下限。     

Effect of drought on the biochemical composition and antioxidant activities of cumin (Cuminum cyminum L.) seeds

This study is designed to examine the yield components, fatty acid, and essential oil compositions and phenolic contents fruit essential oil composition, the total phenolic amounts as well as the antioxidant activities of cumin (Cuminum cyminum L.) seeds under drought. This plant is one of the most common aromatics in the Mediterranean kitchen. Plants were treated with different levels of water deficit: control (C), moderate water deficit (MWD) and severe water deficit (SWD). Our results indicated that MWD improved the number of umbels per plant as well as the number of umbellets per umbel and the seed yield, in comparison to the control, but it decreased under SWD. Fatty acid composition analysis indicated that petroselinic acid was the major fatty acid (55.9%) followed by palmitic (23.82%) and linoleic (12.40%) acids. Water deficit enhanced the palmitic acid percentage and affected the double bound index of the fatty acid pool and thus the oil quality. The essential oil yield was 1.64% based on the dry weight and increased by 1.40 folds under MWD. Nevertheless it decreased by 37.19% under SWD in comparison to the non treated seeds. Drought results on the modification of the essential oil chemotype from γ-terpinene/phenyl-1,2 ethanediol in the control seeds to γ-terpinene/cuminaldehyde in stressed ones. Besides, total phenolic contents were higher in the treated seeds (MWD and SWD). Results suggest that water deficit treatment may regulate the production of bioactive compounds in cumin seeds, influencing their nutritional and industrial values. Besides, antioxidant activities of the extracts were determined by four different test systems, namely DPPH, β-carotene/linoleic acid chelating and reducing power assays and showed that treated seeds (MWD and SWD) exhibited the highest activity.     

Diurnal temperature fluctuation effects on potatoes grown with 12 hr photoperiods

This study was designed to characterize the growth responses of potato (Solanum tuberosum L.) to diurnal temperature fluctuations. Potato plants of two cultivars, Norland and Denali, were grown for 90 days under 12 hr photoperiod in walk-in growth rooms at the University of Wisconsin Biotron. The alternating temperature was 22 C light/14 C dark and compared to a constant 18 C as control. At all temperature regimes vapor pressure deficit was maintained at 0.62 kPa (70% relative humidity [correction of humdidity] at 18 C). Plant height, plant dry weight, tuber dry weight, and harvest index were overall greater under the warm light/cool dark alternating temperatures than under the constant temperature. The differences between temperature treatments were greater for Denali than for Norland. Alternating temperatures increased Denali tuber weights by 25%, but no significant increase was found with Norland. Also the total plant weight was increased over 20% with Denali, but increased with Norland in only one of the two replications of the experiment. This study documents that alternating temperatures are a benefit to some cultivars but may not be of benefit to all cultivars.     

灌溉策略对冬小麦水分利用和生长的影响

为探究不同灌溉策略下冬小麦水分利用和生长的情况,在总灌溉量相同的前提下设置拔节水+开花水单次参比蒸散30%灌溉(W1)、拔节水+开花水单次参比蒸散60%灌溉(W2)和拔节水+开花水大水漫灌(W3)3种灌溉策略,利用称重式蒸渗仪和diviner 2000研究了不同灌溉策略下冬小麦的耗水动态、蒸散特征和水分利用效率。结果表明,大水漫灌处理(W3)下冬小麦主要利用上层(0～50 cm)土壤水分,而低速率灌溉(W2和W1)处理增强了植株根系对深层(70～100 cm)土壤水分的吸收;同时,低速率灌溉可以降低蒸散速率,W3、W2和W1的日蒸散速率最大值在拔节水灌溉期间分别为13.20、10.82和10.58 mm·d^-1,在开花水灌溉期间分别为15.10、10.57和9.10 mm·d^-1,其中低速率灌溉主要降低了单日蒸散的午间高峰值,减少了无效耗水。大水漫灌处理不利于生长后期株高的增加,而低速率灌溉不仅有利于株高的形成,也有利于叶片维持较高水平且稳定的SPAD值,保证了籽粒灌浆,使得W2处理的穗粒数和千粒重较W3处理分别提高7.25%和3.93%。综合来看,低速率灌溉策略通过低量持续的供水改变了冬小麦植株根系对土壤水利用的层次,减少无效水蒸散,维持叶片稳定的光合能力,提高了产量和水分利用效率。     

Yield and seed quality of Plantago ovata and Nigella sativa under different irrigation treatments

Employing locally adapted plants together with irrigation scheduling based on developmental stage in semi-arid and arid regions may provide an opportunity to optimize irrigation efficiency, and water savings in regions where water resources are limited. To investigate this water saving potential, the final seed yield and quality of two local plant species were investigated under water deficit conditions over two growing seasons (2003, 2004) in the northeast of Iran. In this study, black cumin (Nigella sativa L.) which is used locally as an anti-microbial and isabgol (Plantago ovata Forsk.) which is used as an anti-diabetic plant were exposed to four different irrigation regimes. Weekly irrigation was the control, and the three treatments based on developmental stage for both species were termination of irrigation at blooming (folded flowers), flowering, and seed formation. Isabgol seed yield was lower for all of the water deficit treatments compared to control, but black cumin showed tolerance to water deficit except when irrigation was terminated at seed formation. The lowest seed yield was obtained when irrigation was stopped at the blooming stage, and the number of seeds per plant was the main yield component affected. One thousand seed weight for both species was relatively stable across all irrigation treatments, and higher seed yield was consistent with higher straw yield and plant height. Our results did not show any reduction in oil concentration for black cumin or mucilage percentage for isabgol across all water deficit treatments.