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Temperature in greenhouse is often elevated during tomato(Lycopersicon esculentum L.) plants growing season, which causes the change of crop water requirement. With the climate change, high temperature episodes will become much more common. Tomato seedlings were treated by 80% ETc (Evapotranspiration), 100% ETc and 120% ETc of irrigation amounts under elevated temperature in greenhouse. The influence of supplementary irrigation on photosynthesis and quality of seedlings were investigated. Results showed that both net photosynthetic rate (Pn) and PS II photochemical efficiency (Fv/Fm) in plants with 120% ETc irrigation were the highest, while the minimum fluorescence (Fo) was the lowest among treatments. With the decrease of Pn in treatments of 80% ETc and 100% ETc, the stomatal limitation values (Ls) increased significantly. Seedling health index and growth function showed the following trends: 120%ETc>100%ETc>80%ETc. There was a positive relationship between irrigation amount and physiological indexes in tomato seedlings exposed to elevated temperature. 80% ETc and 100% ETc worsened the effects of heat stress, while 120% ETc irrigation amount mitigated the stress and enabled plants to thrive under elevated temperature. [ABSTRACT FROM AUTHOR]

High temperatures in summer can prevent people from using urban green spaces. Irrigating urban green spaces is a promising strategy to reduce temperatures. In this study, we aimed to a) identify the proportional contribution of different irrigation cooling mechanisms and b) quantify the impacts of different irrigation amounts (from 2 to 30 mm d−1) on the cooling effect of irrigating turfgrass in Melbourne, Australia. We first used a field experiment in Melbourne to provide empirical data to calibrate and verify the performance of an urban ecohydrological model, UT&C. Then, we used UT&C to predict the impacts of irrigating turfgrass on evapotranspiration, the energy balance and microclimate. UT&C predicted that irrigating turfgrass 4 mm d−1 would increase the evaporation from grass canopy and soil surface by 0.2 and 0.6 mm d−1, respectively, whereas it would reduce transpiration by 0.6 mm d−1 due to intercepted water covering part of the grass canopy following the irrigation. UT&C predicted that daytime (10:00–16:59) mean air temperature reductions would increase from 0.2 to 0.4 °C when the irrigation amount increased from 2 to 4 mm d−1. However, increasing the irrigation amount beyond 4 mm d−1 would not increase the cooling benefits. [Display omitted] • We measured the cooling effects of irrigating urban green spaces. • We used a model to identify cooling mechanisms and optimal ideal irrigation amount. • Irrigating grass increased evaporation from soil surface and canopy interception. • Increasing irrigation amount beyond 4 mm d−1 would not strengthen cooling effect. • Irrigating grass 4 mm d−1 significantly reduced daytime air temperature by 0.4 °C. [ABSTRACT FROM AUTHOR]

Water and nitrogen (N) are two of the most important inputs for high maize yields. An experiment was carried out in random group design to study the effects of irrigation amount and frequency on NO3--N distribution and crop water use efficiency in maize field under film-hole irrigation in 2012 and 2013 and compare and analyze water consumption between film-hole and border irrigation. There were three irrigation amount treatments, which were 37.48mm, 52.47mm and 67.47mm, and three irrigation frequency, which were 3,4,5 frequencies during the planting period under film-hole irrigation. In addition, there was also a border irrigation treatment with 67.47mm and 5 irrigation frequencies as control group. The research results showed that, NO3--N concentration in 80-100cm soil layers increased with irrigation water increase especially in maize jointing and heading stage under the same irrigation frequency. And NO3--N concentration peak of 5 irrigation frequencies appeared at 50cm soil layers, however, that of 3 and 4 irrigation frequencies appeared at 40cm soil layers. Moreover, film-hole irrigation can transform soil ineffective evaporation into effective crops transpiration and improve crop production efficiency as compared with border irrigation. To summarize, taking maize yield, crop water use efficiency and economic benefit of water using into consideration, one-time irrigation amount of 52.47mm and 4 irrigation frequencies are recommended to be used in film-hole irrigation. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Management of organic mailer and irrigation after anthesis will increase the capacities of water conservation and supply in maize field, with consequences on photosynthetic performance and yield under water-saving condition. We analyzed the gas exchange parameters and the performance of the photosystem II of ear leaves, and yield of maize cultivars Zhengdan 958, under three modes of ditch-buried organic matter (no straw returned; Mo, wheat straw returned; M,, mixtures of cow manure and wheat straw returned; M2) before seeding with two irrigation levels after anthesis (normal irrigation; W1, water-saving irrigation; W2). The results showed that M2 treatment significantly increased photosynthetic capacity and dry matter accumulation after anthesis compared with M, treatment. Compared with water-saving irrigation, normal irrigation enhanced the photosynthesis of ear leaves. M2W1 treatment significantly increased net photosynthetic rate (Pn), stomatal conductance (g), transpiration rate ( Tt), and performance of photosystem II (σpo and ωo) of ear leaves after anthesis, while reduced intervellular CO2 concentration ( Ci). In addition, M2W1 treatment significantly increased light utilization efficiency and maintained higher photosynthetic properties in ear leaves, and significantly increased dry mailer accumulation and grain yield. Water-saving irrigation reduced photosynthetic performance of ear leaves, which declined the yield. But compared M2 with M0, water use efficiency, grain growth rate and yield increment under water-saving irrigation were higher than those under normal irrigation. Thus, mixtures of cow manure and wheat straw returned combined with normal irrigation could significantly increase photosynthetic properties of ear leaves and dry mailer accumulation, which were the major reasons for yield enhancement. Importantly, the mixture of cow manure and wheat straw returned combined with water-saving irrigation could decrease the loss of crop yield resulted from lower irrigation. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Taking cucumber as experimental plant, an experiment was conducted to study the effects of irrigation amount and fertigation methods on growth, yield and quality of cucumber in greenhouse. The experiment had designed two irrigation levels, i.e. 100% ET0(W1) and 75% ET0 (W2), and four fertigation fertilization ratios, i.e. 100%, 66.6%, 33.3% and 0% (Z100, Z66, Z33, Z0) fertigation of a total amount of (360:180:540 kg·hm-2) (N:P2O5:K2O) by 8 times with the corresponding remainders (0%, 33.3%, 66.6% and 100%) were applied to soil as basic fertilization before the planting according to the recommended fertilization rate, and no fertilizer treatment was set up as the control (CK). Results showed that irrigation and fertilization levels had positive correlations with plant height, leaf areas, dry mass, yield and quality of cucumber. Yield at W1Z100 was the highest, reaching 67760 kg·hm-2. W2 treatment increased the mean water use efficiency (WUE) by 9.4% compared to W1. W2Z100 treatment had the highest WUE, reaching 47.13 kg·m-3. Yield at W2Z100 was only 3.4% lower than the maximum, but saved 25% of water. Yield and dry matter at Z100 were 15.3% and 16.8% higher than at Z0, respectively, the cucumber fruit vitamin C, soluble protein and soluble sugar contents were increased, and the water use efficiency was increased by 19.1%. W2Z100 treatment was the best treatment which could enable cucumber to obtain both the high-yield and the high-quality. [ABSTRACT FROM AUTHOR]

Jatropha curcas is the most promising energy tree, and soil moisture is the key factor which affects the seedling quality and water use efficiency of J. curcas. With aims to evaluate the effect of different irrigation amount on growth, morphological characteristics and water use of J. curcas, a pot experiment was conducted with four irrigation amounts, i. e. , W1:472. 49 mm, W2: 228. 79 mm, W3:154. 18 mm and W4:106. 93 mm, respectively. Compared with W1 treatment, the leaf area and stem cross-section area of base significantly decreased in W2, W3 and W4 treatments, but Huber value significantly increased, which could improve the efficiency of water transfer from root to shoot, thus enhance the capability of resistance to drought stress. Compared with W1 treatment, the healthy index of J. curcas seedlings decreased slightly in W2 treatment but significantly decreased in W3 and W4 treatments. Hence, the irrigation amount from 228. 79 to 472. 49 mm was beneficial to increase the healthy index of J. curcas seedlings. Compared with W1 treatment, irrigation water was saved by 67. 4% in W3 treatment, and the total dry mass and evapotranspiration significantly decreased by 17. 4% and 68. 6%, and the irrigation water use efficiency and total water use efficiency increased by 153. 2% and 163. 2%, respectively. In the condition of this study, the irrigation amount of 154. 18 mm was beneficial to increase water use efficiency. [ABSTRACT FROM AUTHOR]

A 2-year (2009 and 2010) field experiment was carried out to investigate the effects of irrigation amount (300, 375, and 450 mm) and irrigation frequency (once every 3-, 7-, and 10 days) on the soil water distribution and cotton water use efficiency (WUE) under mulched drip irrigation in North Xinjiang. When the irrigation amount was 375 mm, irrigation once every 3 days induced a higher water content in surface soil (0-20 cm) in the whole growth season of cotton but made the deeper (below 40 cm) soil not moistened enough. Irrigation once every 10 days benefited the irrigation water penetrated downward or sideways and made the deeper soil have a higher water content; however, this drip irrigation did not replenish water in time, and made the surface soil water content lower. Overall, drip irrigation once every 7 days benefited the uniform distribution of irrigation water in soil profile. Under the same irrigation frequencies, the larger the irrigation amount, the higher the soil water content. The cotton water consumption in all treatments had the similar pattern, i. e. , lower at seedling stage (averagely <1. 7 mm · d-1 ), increased gradually since squaring stage and reached the maximum at full bloom stage (about 8. 7 mm·d-1), and decreased at open-boll stage (about 1. 0 mm·d-1). Under the natural condition, the total cotton water consumption had close correlation with irrigation amount but poor correlation with irrigation frequency, and the cotton WUE decreased significantly with increasing irrigation amount. When the irrigation amount was 300 mm, the WUE was higher but the yield production decreased markedly, whereas excessive irrigation (450 mm) had no significant yield-increasing effect but wasted water. It was suggested that irrigation with an amount of 375 mm and a frequency of once every 7- or 10 days could be an appropriate drip irrigation mode for the local cotton field under natural condition. [ABSTRACT FROM AUTHOR]

A field experiment was conducted to study the effects of irrigation amount and nitrogen fertilization rate on wheat yield and soil nitrate content. With the increase of irrigation amount, the soil nitrate content in 0-200 cm layer at the same nitrogen fertilization rates had a trend of decrease-increase-decrease. Under irrigation, the soil nitrate content was significantly lower in 0-80 cm layer while significantly higher in 80-200 cm layer, compared with the control. As the irrigation amount increased, the translocation of soil nitrate nitrogen to deeper layers accelerated dramatically, with the content decreased in 0-80 cm layer, increased in 120-200 cm layer, and peaked in 120-140 cm layer. When the nitrogen fertilization rate increased from 210 kg·hm-2 to 300 kg·hm-2, the soil nitrate content at the same irrigation amounts increased significantly through anthesis, filling, and maturity stages. With the increase of irrigation amount, the grain yield decreased after an initial increase, being the highest when the irrigation amount in whole growth period was 60 mm. The grain yield, grain protein content, and grain protein yield all increased significantly with increasing nitrogen fertilization rate. Under the conditions of the present experiment, the treatment with nitrogen fertilization rate 210 kg N·hm-2 and irrigation amount 60 mm (split into two times) had the highest grain yield, grain protein content, grain protein yield, and harvest index but the least NO3--N leaching, being the more available irrigation and nitrogen fertilization mode for wheat production in the study area. [ABSTRACT FROM AUTHOR]

Lycium barbarum is an important traditional medicinal plant in China. Under controlled condition, a field experiment was conducted to study the effects of different monthly irrigation quota on the leaf structure, photosynthetic physiology, and fruit yield of L. barbarum, aimed to determine an appropriate irrigation amount for the plant. When the monthly irrigation quota was less than 900 m3∙hm-2, the leaf area, leaf thickness, palisade tissue thickness, cell tense ratio (CTR), net photosynthetic rate (Pn), intrinsic water use efficiency (WUE), stomatal limitation value (Ls), and fruit yield of L. barbarum all increased significantly with monthly irrigation quota, while leaf stoma density and intercellular CO2 concentration (Ci) showed a reverse trend. When the irrigation quota was more than 900 m3 ∙hm-2, the Ci increased with irrigation quota, the leaf area, stoma density, and fruit yield had no obvious change, whereas the other indices showed a reverse trend. The leaf transpiration rate and Gs were the highest at irrigation quota 450 m3 ∙hm-2, being 8.02 and 324 mmol∙m-2 ∙s-1, respectively; whereas at other irrigation quota, these two indices were lower than the control. In terms of saving water, the monthly irrigation quota 900 m3 ∙hm-2 was more appropriate for Lycium barbarum. [ABSTRACT FROM AUTHOR]

A field experiment was conducted to examine the effects of irrigation amount on the water consumption, flag leaf physiological characteristics, and grain yield of wheat under the nitrogen application rates 180 kg∙hm-2(N180) and 240 kg∙hm-2(N240). Four irrigation regimes were designed, i. e. , no irrigation during whole growth period (W0), irrigation with 60 mm water before sowing (W1), irrigation with 60 mm water before sowing and at jointing stage, respectively (W2), and irrigation with 60 mm water before sowing, at jointing stage, and at flowering stage, respectively (W3). In treatment W0, the water consumption amount below 100 cm soil layer was lower than that in other treatments; and in treatments W1 and W2, the water consumption amount in 100-200 cm and 0-200 cm soil layers was higher than that in treatment W3. The soil water consumption amount in 0-80 cm soil layer, the consumption percentage from flowering to maturing stage, and the total water consumption amount were all higher under N240 than under N180. At mid and late grain-filling stages, the relative water content (RWC) and water potential (ψw) of flag leaves were higher in treatments W2 and W3 than in treatments W0 and W1. The RWC and ψw at late grain-filling stage were higher in treatments N240 W0 and N240 W1 than in N180 W0 and N180 W1, respectively, but had no significant differences between treatments N240W2 and N180W2, and N240W3 and N180W3. In this study, treatment N180W2 had the higher grain yield, water use efficiency (WUE), and nitrogen use efficiency, while over-irrigation increased the water consumption amount, and decreased the WUE, irrigation water use efficiency, and irrigation benefit. [ABSTRACT FROM AUTHOR]

Field experiments were conducted in Tai' an and Yanzhou of Shandong Province in 2004-2005 and 2005-2006 to study the effects of irrigation stage and amount on the accumulation and translocation of fructan in winter wheat penult stem and sheath after anthesis and the water use efficiency. No irrigation in whole growth period promoted the translocation of fructan from penult stem and sheath to grain at late grain-filling stage. Irrigation with 60 mm water at jointing and anthesis stages increased the flag leaf photosynthetic rate and photo-assimilate accumulation after anthesis, and the contribution of the photo-assimilates to the grain. Irrigation with 60 mm water at jointing, anthesis, and grain-filling stages, and with 90 mm water at jointing and anthesis stages decreased the flag leaf photosynthetic rate at late grain-filling stage, increased the photo-assimilate accumulation before anthesis and the contribution of the photo-assimilates to the grain, and reduced the translocation of the photo-assimilates after anthesis to the grain. Excessive irrigation also increased the contents of fructan with the degree of polymerization (DP) > or ≥ 4 and = 3 in penult stem and sheath at late grain-filling stage, limiting the translocation of fructan from penult stem and sheath to grain. Irrigation with 60 mm water at jointing and anthesis stages led to a higher grain yield and the highest water use efficiency, while irrigation with 60 mm water at jointing, anthesis, and grain-filling stages, and with 90 mm water at jointing and anthesis stages had little effects on the grain yield but decreased the water use efficiency. [ABSTRACT FROM AUTHOR]