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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]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office 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.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office 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.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office 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.)

Biodegradable film (BF), as a superior substitute for traditional polyethylene film (PF), has experienced a consistent increase in China. However, a significant research gap persists regarding the utilization of BF in assessing farmland carbon balance. This experiment examined the responses of maize growth, yield, irrigation water productivity (IWP), CO 2 emissions, and field net carbon sequestration (NCS) to two BF types (BF 1 , 100-day induction period, and BF 2 , 80-day induction period), and PF, and three irrigation amounts (I 1 , I 2 , I 3 : 5250, 5625, and 6000 m3 ha–1), by conducting a two-year (2019–2020) field trial in a typical arid and semi-arid region of China. The results indicated that biodegradable film mulching (BFM) negatively affected maize growth, resulting in reduced yield and IWP. Especially under the I 1 irrigation level, the biodegradable film reduced maize yield by 6.26%–13.99% and IWP by 6.64–13.85%. Notably, in the I 2 irrigation level, BF 1 mulching had a comparable impact on maize yield and IWP to that of PF. Additionally, the increase in irrigation amounts exerted a more pronounced promoting effect on maize total biomass than on yield and IWP. Concerning carbon balance, short-term BF application resulted in reduced CO 2 emissions (5.74–6.30% under BF 1 and 9.27–12.37% under BF 2), without any significant impact on NCS in cropland. Taking into account the economic value of maize and farmland ecology, we recommended utilizing irrigation amounts of 5625 m3 ha–1 for BF application in arid areas, while opting for a BF with a longer induction period whenever feasible. • Biodegradable film mulching reduces maize yield and irrigation water productivity. • Biodegradable film mulching significantly decreases soil CO 2 emissions. • Increasing irrigation compensates for yield loss due to biodegradable film mulching. • Biodegradable film with a 100-day induction period is an ideal covering material. [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]

Introduction Iran is the fourth world producer of figs with an average of 75,833 tons from 1993 to 2013 (FAO, 2016). Estahban area provides about 90% of dried fig in Iran (Jafari, Abdolahipour-Haghighi and Zare, 2012). The rainfed fig orchards in this area have been extremely affected by severe drought in recent years, leading to 10% to 80% reduction in fig trees and fruit in 2010, respectively (Jafari, Abdolahipour-Haghighi and Zare, 2012). For this reason, the tendency to apply supplemental irrigation in Estahban fig orchards has increased in previous years. However, the lack of information about the amount, timing, and application position of supplemental irrigation to achieve efficient use of water in this area makes it difficult to deal with this issue in the study area. The main objective of this study was, thus, to investigate the effect of different amounts and times of supplemental irrigation at different distances from tree trunk on soil water variation, quantity of fruits, and fig growers’ income under drought conditions.

The mechanism of greenhouse tomato growth and yield under the integrated water and fertilizer of moistube irrigation (MI) is not clear. Thus, to fill the research gap, a completely randomized trial design was used to study the effects of different irrigation amounts (I; to realize different I, the tube working pressure was 1 (I1), 2 (I2), 3 (I3) m) and fertilizer amounts (F, N-P-K: 20%-20%-20%; the F at a single time was 100 (F1), 200 (F2) and 300 (F3) kg/ha) on growth and yield of tomato. The results showed that with an increase in I, the photosynthetic rate (Pn) of leaves and total dry matter mass (TDM) first increased and then decreased, while the nutrition and the flavor indexes of fruit decreased. With an increase in F, the Pn of leaves, the TDM of tomato and the fruit quality increased at first and then decreased. The effects of I on the yield of tomato was higher than that of F. With an increase in I, the partial fertilizer productivity (PFP) increased at first and then decreased, and the water use efficiency (WUE) decreased by 13.96%. With an increase in F, the WUE increased at first and then decreased, and the PFP decreased by 148.97%. The conclusion based on a spatial analysis was consistent with the comprehensive evaluation of yield and water use efficiency, which showed that I2F2 was the best.

This experiment aimed to determine the crop evapotranspiration (ETc) and groundwater input in total water used by wheat (Triticum aestivum) crop and to use the CROPWAT model to predict the crop ETc. To estimate the on-field ETc and groundwater contribution, the combining lysimeter technique was used. The water levels below the soil surface were kept at 1.60, 2.20, and 2.80 m and each water table depth was replicated three times. A field experiment was conducted under silt loam (SL) and silty-clay loam (SCL) soil conditions. The climatic parameters and water balance components were recorded accordingly. The on-field ETc was compared with the predicted ETc by CROPWAT model. Under SL soil, the observed ETc was 442, 427 and 401 mm and under SCL soil conditions it was observed as 419, 402 and 389 mm at the water table depth of 1.60, 2.20, and 2.80 m, respectively. The ETc was reduced with an increase in water level below the surface. The groundwater contribution under SL and SCL soil was observed as 50%, 41%, and 30% and 43%, 34%, and 24%, at 1.60, 2.20 and 2.80 m water table depth, respectively. The predicted ETc by CROPWAT model for SL and SCL soil conditions was 428.8 and 410.7 mm, respectively. The projected ETc was equal to the average ETc observed under lysimeter experiment. Thus, the use of CROPWAT model is recommended to overcome waterlogging and salinity problems and to conserve water resources. Considering lysimeter results, the irrigation applications must be revised for shallow water table levels due to adequate contribution of groundwater. [ABSTRACT FROM AUTHOR]

The development of irrigated agriculture in northwest China is restricted by shortages of fresh water and groundwater salinization. Saline water irrigation may cause salt accumulation in the soil, which results in salt stress to roots. The effects of water salinity and irrigation amount on wheat root distribution and yield, as well as soil salt distribution, were evaluated in field experiments conducted in 2014 and 2015 at the Shiyanghe Experimental Station of the China Agricultural University (102°52'E, 37°52'N), located in the Liangzhou District, in the city of Wuwei in northwest China. A total of 12 treatments including 4 levels of irrigation water salinity as indicated by electrical conductivity (0.65, 3.2, 5.2, and 7.1 dSm-1) and 3 levels of irrigation amount (205, 280, and 355 mm), were established using a randomized block design. Freshwater with an electrical conductivity of 0.65 dSm-1 and an irrigation amount of 355 mm was used as the control for salinity and irrigation level. The results showed that the influence of irrigation amount and water salinity on root distribution was mainly in the top 40-cm. Irrigation amount had no statistically significant (p > 0.05) effects on the average root length density (RLD) in the 2-year experiment. A decrease in irrigation amount reduced root biomass (RB) at maturity when water salinity ranged from 0.65 to 5.2 dSm-1. Water salinity less than 3.2 dSm-1 stimulated root growth in the soil layers 10-40-cm at the heading stage without obvious yield reduction or salt accumulation. However, water salinities of 5.2 and 7.1 dSm-1 led to decreases in RLD in the 0-10-cm layer and RB at the maturity stage, and a significant decrease in yield (p < 0.05) in both years. The interaction effects of irrigation amount and water salinity had no statistically significant (p > 0.05) effects on root parameters and yield. In the absence of rainfall, a regime with irrigation amounts between 205 and 355 mm and water salinity between 0.65 and 5.2 dSm-1 can ensure a 70% yield. [ABSTRACT FROM AUTHOR]

Activated water irrigation has been widely investigated as an effective production increasing measure. However, the response of activated water irrigation in plant growth and water use efficiency (WUE) with the irrigation amount is not well understood. Here, a pot experiment was conducted to determine the effects of activated water irrigation on winter wheat growth, yield, and WUE under irrigation amount. Twelve treatments included four irrigation water types, (i) tap water (TW), (ii) tap water with magnetization (MW), (iii) tap water with oxygenation (OW), (iv) tap water with magnetization and oxygenation (M&OW), and three irrigation amounts, (1) 80% of the field capacity (FC), (2) 65%FC, and (3) 50%FC. The results indicated that activated water irrigation improved the plant height, leaf area, aboveground biomass, and photosynthetic characteristics at each growth stage of winter wheat. However, the yield and WUE varied with water type and irrigation amount. With 80%FC, the yield and WUE of MW were significantly greater by 35.7% and 53.9% than TW. The yield and WUE of OW were greater by 11.4% and 23.1% than TW. With 65%FC, the yield of MW, OW, and M&OW were greater by 43.9%, 46.3%, and 14.6% than TW, respectively. WUE of MW, OW, and M&OW were greater by 37.0%, 37.0%, and 11.1% than TW, respectively. With 50%FC, the yield of OW and M&OW were significantly greater by 77.3% and 122.7% than TW. WUE of OW and M&OW were significantly greater by 41.4% and 75.9% than TW (p < 0.05). Overall, the research provides clear evidence that OW is an effective way to increase yield and WUE, MW and M&OW should be applied in suitable soil water conditions.

【Objective】 To define the interaction model between irrigation amount and planting density of the canopy structure of spring corn population with high efficiency and coordination in the irrigated area of Tumed Plain. 【Methods】 Xianyu 335 as the test varieties,two test factors of irrigation gradient and planting density were set. Two water gradients,normal irrigation treatment(75% field moisture capacity,S1) and moderate water stress(45% field moisture capacity,S2) for irrigation amount and two planting density treatments,75 000 plants/hm²(M1) and 105 000 plants/hm²(M2) were set in the study. The samples were taken after water stress treatment to determine soil physical index,chemical index,spring corn leaf photosynthetic characteristics,chlorophyll fluorescence parameters,relative content of chlorophyll,dry matter accumulation above the ground,and grain yield. The effects of irrigation amount,planting density and their interaction on flowering photosynthetic performance and grain yield of spring corn were analyzed.【Results】 Compared with normal irrigation treatment(S1),moderate water stress (S2) significantly could reduce grain yield,water consumption(ET) of whole growth period,water use efficiency(WUE),irrigation water production efficiency(IWPE),dry matter accumulation(P<0.05). Compared with the treatment of normal irrigation combined with 75 000 plants/hm²(S1M1),in the treatment of normal irrigation combined with 105 000 plants/hm²(S1M2),the relative content of chlorophyll(SPAD) decreased by 2.859,the maximum photochemical efficiency(Fv/Fm) decreased by 0.033,the photosynthetic index(PI) decreased by 0.882,the net photosynthetic rate(Pn) decreased by 2.130 μmol/(m²·s),the transpiration rate (Tr) decreased by 1.153 μmol/(m²·s),and the stomatal conductance (Gs) decreased by 0.054 μmol/(m²·s). Leaf water use efficiency(WUEL) showed an increasing trend with the increase of planting density. Compared with S1M1,WUEL of S1M2 increased by 0.492 μmol/mmol;the correlation coefficients between grain yield and Fv/Fm,Pn were 88% and 92%,respectively. Therefore,Fv/Fm and Pn were given priority in variety selection. Moderate water stress and high planting density could significantly reduce the photosynthetic performance and grain yield(P<0.05).【Conclusion】 In the irrigated area of Tumed Plain,under normal irrigation combined with planting density of 105 000 plants/hm²(S1M2),the plant populations coordination of spring corn was better,and the grain yield was 11 507.79 kg/hm². [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology 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.)

Desertification control is an important issue that must be considered in modern society. In order to effectively improve the accuracy and practicability of the evaluation algorithm of desertification control effect, the Alhagi sparsifolia index under different irrigation amount was taken as the research object, and the evaluation algorithm of desertification control effect was proposed. In the "vegetation-sandstorm-soil" index system, a number of indexes were selected according to the core environmental parameters of Alhagi sparsifolia and grassland desertification. And the analytic hierarchy process, remote sensing, geographic information system, and landscape technology were used to assign index weights of desertification control capacity, which were calculated by multiple discriminant matrices. Finally, the data regression analysis was performed based on remote sensing and computer image information screening and processing to determine the final evaluation results. The experimental data show that the true positive rate of the algorithm in this paper is between 160 and 200, which is within a large range of advantages, indicating that the overall evaluation accuracy of the algorithm is high and the evaluation effect is perfect. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences 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.)

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]

In order to explore the irrigation index of winter wheat with sprinkling irrigation in North China, a 2-yeargrowing season(2010-2012) field experiment was carried out to investigate the effects of economic yield, grain quality and water use efficiency of winter wheat with different sprinkling irrigation. The results show that the different effects of water-deficits on biomass, economic yield, grain quality and water use efficiency based on the growing stages in which the water deficits are applied. There is no significantly decreased grain yield, but the grain quality water use efficiency and irrigation water use efficiency are significantly increased and the protein ratio and gluten ratio have been improved when water deficits applied during from turning green to elongation stage and grain filling of winter wheat. Comprehensive consideration economic yield, grain quality, water use efficiency especially irrigation water use efficiency, irrigation strategy of T2, T3 and T6 can be used as appropriate sprinkling irrigation mode for the local winter wheat. [ABSTRACT FROM AUTHOR]

In order to explore the effects of different irrigation amounts on the length and width of new citrus leaves under the pre¬cise root domain irrigation technology, citrus was taken as the research object and set different irrigation amount for irrigation. In the experimental group under the precise root field irrigation, 35, 30, 25L/ (plant • times) were respectively set and irrigated once in sev¬en days； in the control group under the micro - sprinkling irrigation method, 130L/(plant • times) irrigated once in 15 days. After ir¬rigating different amount of water, the growth of slightly new tip of the tree and the length and width of new leaves were recorded. Re¬sults showed that the root domain precision irrigation under different irrigation amount had a significantly influence on the new tip of the tree and the length and width of new leaves. In the 14 days observation period, test II had the best growth potential, the total growth of the new tip of the tree was 72. 1 mm, compared with the control group, the growth volume increased by 17. 7 mm and increased by 32.5% year - on - year. The total growth of new leaf length was 48. 9 mm, increased by 9. 6 mm compared with the control group, in¬creased by 24.4% year - on - year, and the total growth of leaf width was 23. 3 mm, which was higher than that of the control. The growth of the group increased by 5. 3 mm, a year - on - year increase of 29. 4% . Therefore, the irrigation amount of 30 L/( plant • times) under the precise root domain irrigation technology is more suitable for the growth of fresh citrus leaves. [ABSTRACT FROM AUTHOR]

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department 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.)

The characteristics of the growth of winter wheat are the basis for determining a reasonable amount of irrigation water, regulating wheat growth, improving environmental conditions and increasing yield. Plant height, leaf area index (LAI), dry-matter accumulation (DMA) and harvest index (HI) are commonly used as indices of the growth of winter wheat, and growing degree days (GDD) is an important meteorological factor affecting these indices. The characteristics of plant height, LAI and dry-matter accumulation of winter wheat in 50 regions of China were analyzed based on qualitative analyses and quantitative calculations. Normalized logistic models were used to analyze the growth indices based on GDD, and we discuss the relationships between maximum LAI, HI and irrigation amount. The rate of increase in the height of winter wheat increased with GDD and was low in the early stages, high in the intermediate stages and low in the late stages. Plant height was highest when GDD increased to about 1200 °C. LAI first increased and then decreased, and the trends of change of LAI were similar among the regions. LAI was highest when GDD increased to about 1200 °C. LAI was near its maximum when plant height was near its maximum, but dry-matter accumulation still increased with GDD. The rate of dry-matter accumulation was highest when GDD was about 1200 °C. Plant height and LAI were near their maxima, but nutrients were mainly supplied to the booting and filling stages, which maintained the accumulation of dry matter. A quadratic polynomial function could describe the relationship between HI and maximum LAI. The optimal HI was 0.45 when maximum LAI was 6.5. The relationship between the maximum LAI and irrigation amount was also described by a quadratic polynomial function. Maximum LAI was 6.45 when irrigation amount throughout the growth period was 466.4 mm, when HI was approximately optimal. The growth of winter wheat in China could be simulated by GDD and a normalized logistic model, and maximum LAI and irrigation amount for the optimal HI could be obtained. This study provides a theoretical basis and an available method for predicting the yield of winter wheat and improving other models of crop growth. [ABSTRACT FROM AUTHOR]

Achieving optimal balance between maize yield and water use efficiency is an important challenge for irrigation maize production in arid areas. In this study, we conducted an experiment in Xinjiang China in 2016 and 2017 to quantify the response of maize yield and water use to plant density and irrigation schedules. The treatments included four irrigation levels: 360 (W1), 480 (W2), 600 (W3), and 720 mm (W4), and five plant densities: 7.5 (D1), 9.0 (D2), 10.5 (D3), 12.0 (D4), and 13.5 plants m−2 (D5). The results showed that increasing the plant density and the irrigation level could both significantly increase the leaf area index (LAI). However, LAI expansion significantly increased evapotranspiration (ETa) under irrigation. The combination of irrigation level 600 mm (W3) and plant density 12.0 plants m−2 (D4) produced the highest maize yield (21.0–21.2 t ha−1), ETa (784.1–797.8 mm), and water use efficiency (WUE) (2.64–2.70 kg m−3), with an LAI of 8.5–8.7 at the silking stage. The relationship between LAI and grain yield and evapotranspiration were quantified, and, based on this, the relationship between water use and maize productivity was analyzed. Moreover, the optimal LAI was established to determine the reasonable irrigation level and coordinate the relationship between the increase in grain yield and the decrease in water use efficiency.

The characteristics of the growth of winter wheat are the basis for determining a reasonable amount of irrigation water, regulating wheat growth, improving environmental conditions and increasing yield. Plant height, leaf area index (LAI), dry-matter accumulation (DMA) and harvest index (HI) are commonly used as indices of the growth of winter wheat, and growing degree days (GDD) is an important meteorological factor affecting these indices. The characteristics of plant height, LAI and dry-matter accumulation of winter wheat in 50 regions of China were analyzed based on qualitative analyses and quantitative calculations. Normalized logistic models were used to analyze the growth indices based on GDD, and we discuss the relationships between maximum LAI, HI and irrigation amount. The rate of increase in the height of winter wheat increased with GDD and was low in the early stages, high in the intermediate stages and low in the late stages. Plant height was highest when GDD increased to about 1200 °C. LAI first increased and then decreased, and the trends of change of LAI were similar among the regions. LAI was highest when GDD increased to about 1200 °C. LAI was near its maximum when plant height was near its maximum, but dry-matter accumulation still increased with GDD. The rate of dry-matter accumulation was highest when GDD was about 1200 °C. Plant height and LAI were near their maxima, but nutrients were mainly supplied to the booting and filling stages, which maintained the accumulation of dry matter. A quadratic polynomial function could describe the relationship between HI and maximum LAI. The optimal HI was 0.45 when maximum LAI was 6.5. The relationship between the maximum LAI and irrigation amount was also described by a quadratic polynomial function. Maximum LAI was 6.45 when irrigation amount throughout the growth period was 466.4 mm, when HI was approximately optimal. The growth of winter wheat in China could be simulated by GDD and a normalized logistic model, and maximum LAI and irrigation amount for the optimal HI could be obtained. This study provides a theoretical basis and an available method for predicting the yield of winter wheat and improving other models of crop growth. [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.)

Although numerous studies have investigated the individual effects of salinity, irrigation and fertilization on soil microbial communities, relatively less attention has been paid to their combined influences, especially using molecular techniques. Based on the field of orthogonal designed test and deoxyribonucleic acid sequencing technology, the effects of saline water irrigation amount, salinity level of irrigation water and nitrogen (N) fertilizer rate on soil bacterial community structure were investigated. The results showed that the irrigation amount was the most dominant factor in determining the bacterial richness and diversity, followed by the irrigation water salinity and N fertilizer rate. The values of Chao1 estimator, abundance-based coverage estimator and Shannon indices decreased with an increase in irrigation amount while increased and then decreased with an increase in irrigation water salinity and N fertilizer rate. The highest soil bacterial richness and diversity were obtained under the least irrigation amount (25 mm), medium irrigation water salinity (4.75 dS/m) and medium N fertilizer rate (350 kg/ha). However, different bacterial phyla were found to respond distinctively to these three factors: irrigation amount significantly affected the relative abundances of Proteobacteria and Chloroflexi; irrigation water salinity mostly affected the members of Actinobacteria, Gemmatimonadetes and Acidobacteria; and N fertilizer rate mainly influenced the Bacteroidetes' abundance. The results presented here revealed that the assessment of soil microbial processes under combined irrigation and fertilization treatments needed to be more careful as more variable consequences would be established by comparing with the influences based on an individual factor, such as irrigation amount or N fertilizer rate. [ABSTRACT FROM AUTHOR]

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department 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.)

• Drip irrigation frequency, amount and fertilizer rate effects on potato were studied. • Irrigation frequency had extremely significant effects on potato growth, yield and quality. • Full irrigation 1.0 ET c obtained the highest yield, quality and partial factor productivity. • Yield and WUE increased as the amount of fertilizer increased. • The best combination of three factors for multi-objective optimization was put forward. Sandy areas in the northern China are the primary regions for potato production, but limited water resources and low water/fertilizer use efficiency limit the sustainable development of agriculture. Field experiments were conducted during 2016–2017 to investigate the effects of different drip irrigation frequencies, water amounts and fertilizer rates on the yield, quality, water and fertilizer productivity of potato in the sandy areas of northern China. The water and fertilizer treatments were evaluated using the TOPSIS method to obtain the optimal combination of irrigation frequency, water amount and fertilizer rate for multi-objective optimization. The irrigation frequency included once every 4 days (D 4), once every 8 days (D 8) and once every 10 days (D 10). The irrigation levels consisted of full irrigation (1.0 ET c , ET c is the crop evapotranspiration), medium irrigation (0.8 ET c) and low irrigation (0.6 ET c). The fertilizer (N-P 2 O 5 -K 2 O) levels included low fertilization (F 1, 100-40-150 kg ha−1), medium fertilization (F 2 , 150-60-225 kg ha−1) and high fertilization (F 3 , 200-80-300 kg ha−1). The results showed that there were significant effects of the irrigation frequency (IF), irrigation level (IL) and fertilization level (FL) on potato growth, yield, quality, water and fertilizer productivity. Using the same irrigation frequency and fertilization level, the highest tuber yield, starch content, vitamin C and partial factor productivity (PFP) were obtained under the full irrigation (1.0 ET c). However, the irrigation water use efficiency (IWUE) decreased as the water supply increased. In addition, these indicators under deficit irrigation increased with the increase in irrigation frequency at the same fertilization level, but the indicators of D 8 were the highest under the full irrigation. Under the same irrigation frequency and irrigation level, the tuber yield and IWUE increased as the fertilization rate increased. However, the PFP decreased as the fertilizer rate increased. The trends in plant height, LAI, dry matter accumulation, plant yield and commodity tubers were similar to that in tuber yield. The starch content and vitamin C under deficit irrigation increased with the amount of fertilizer applied, but they increased first and then decreased with the increase in fertilizer rate under the full irrigation. The change in the content of reducing sugars was opposite to that of the starch. Based on the TOPSIS method, the multi-target optimum scheduling of potato was attained with the irrigation frequency of once every 8 days (D 8), full irrigation(1.0 ET c and high fertilizer (N-P 2 O 5 -K 2 O) rate (F 3 , 200-80-300 kg ha−1). The obtained optimum combination of water and fertilizers can provide a scientific basis for irrigation and fertilization optimization and management in the sandy areas of northern China and in other regions with similar environments. [ABSTRACT FROM AUTHOR]

In water-scarce regions, alternate-furrow irrigation (AFI)—alternately wetting half of the plant roots—has proven to be an effective water-saving approach without compromising yield. However, the extent to which AFI with wastewater affects N cycling genes remains poorly studied. We aimed to investigate changes in main N transformation processes, bacterial and fungal community composition, as well as relative abundance of N cycle-associated genes in soil receiving AFI with swine wastewater. The experimental plan included three irrigation rates, irrigating pepper plants with 50%, 65%, and 80% of the amount of water required under conventional furrow irrigation to prevent the crop suffering water stress. Each treatment had a groundwater irrigation control. We measured edaphic factors, microbial community composition, and relative abundance of genes in rhizosphere and bulk soils. Altering water use in AFI did not exert a significant effect on bacterial and fungal communities. By increasing the irrigation rate of wastewater, relative abundances of nifH, bacterial and archaeal amoA and nosZ genes decreased, whereas those of nirK and nirS genes increased in the rhizosphere soil; nitrification rate did not decrease and the denitrification rate remained unchanged in both rhizosphere and bulk soil, implying that appropriate increase of wastewater use by AFI can improve N use efficiency. [ABSTRACT FROM AUTHOR]

Highlights • The interactions between soil water and groundwater in a paddy field-bund landscape were quantified using HYDRUS-2D. • The groundwater capillary rise contributed 26.1%–31.2% of rice ET with a shallow groundwater table. • Lateral seepage (LS) was the main pathway for water loss through the bund. • The increasing irrigation quota linearly increased percolation while hardly influenced LS. • The most decisive soil saturated hydraulic conductivities for percolation and LS were identified by sensitivity analysis. Abstract Percolation in farmland increasingly is needed to be quantified to improve water use efficiency and mitigate accompanying nutrient loss. Experiments were conducted to measure the soil properties and moisture in a consolidated paddy field-bund landscape during the rice growing season in 2014–2015. The HYDRUS-2D model simulated soil water movement in the landscape with an excellent performance. In the study, the soil properties of the bund were similar to those of the paddy field after land consolidation. Modelling results showed that most percolation in the paddy field occurred along with water input (rainfall and irrigation). Groundwater capillary rise was detected in the coupled conditions of low soil moisture in the root zone and the shallow groundwater table. Percolation accounted for 23.2%–31.3% of water input, and groundwater capillary rise contributed 26.1%–31.2% to rice evapotranspiration. The variation of the soil water content of the bund indicated that lateral infiltration from the paddy field to the bund primarily occurred in the upper bund adjacent to the field, while the lateral seepage was only found in the lower bund below the groundwater level. Vertical percolation and lateral seepage accounted for 10.5%–14.8% of water input lost through the bund, in which the lateral seepage contributed 77.6%–88.4%. Scenario simulation with the calibrated model investigated the impacts of saturated hydraulic conductivity (K s) and the irrigation amount on the percolation and lateral seepage in the landscape. The results implied that percolation increased with the increasing K s of soil. The percolation in the paddy-bund landscape and lateral seepage were most influenced by the illuvial horizon layer of the paddy field. Furthermore, a higher irrigation amount decreased the groundwater capillary rise and aggravated percolation linearly, while it had few effects on lateral seepage. The research suggests a potential adjustment in making irrigation schedules and conducting land consolidation in the rice-planting areas with shallow groundwater depths. [ABSTRACT FROM AUTHOR]

In this study, a field experiment was conducted to investigate the soil water dynamics and water percolation through the deep vadose zone. A calibrated HYDRUS‐1D model was used to simulate the process of soil water movement and the water budget. Based on the measured volumetric soil water contents, the model was well calibrated and validated. Then, we conducted scenario analyses to determine the combined effects of irrigation amount (IA), antecedent soil moisture (AM), crop evapotranspiration, and deep percolation (DP) in an irrigation event. Four IAs (5, 10, 15, and 20 cm) and three AM conditions (AM‐1, AM‐2, and AM‐3) were controlled in the scenario analyses. The results indicate that according to the Se's (effective saturation) values status and the observed or simulated depth, there could be different conclusions on the influence of DP. Under different IAs in dry (AM‐1) and medium (AM‐2) AM status, DP changed slightly; it was 0.39 and 2.47 cm in AM‐1 and 0.40 and 2.48 cm in AM‐2 for the summer maize and winter wheat crop, respectively; the AM had a crucial contribution to DP. While under the condition of wet AM (AM‐3) or small observation depth, the water inputs could have a significant effect on DP. According to increasing irrigation intensity, the higher values of Se (>0.6) in the whole profile were only displayed between 70 and 300 cm at AM‐1, 70–500 cm at AM‐2, and 70‐below 600 cm at AM‐3, which were gradually extended and moved down with increasing AM. Hence, the IA significantly affected the water percolation at a depth of 200 cm, whereas there was a weak influence at 600 cm except in AM‐3. Furthermore, in the higher values of the Se (>0.65) domain, the correlation between IA and DP was an exponential function and significantly under P < 0.05. In addition, DP began to occur when the soil water content was equal to or greater than 0.75 times that of the field water capacity or the Se > 0.65. When the coarse silt layer became embedded in the silt clay soil profile, it lagged the process of water transport but did not affect permeability in the end. [ABSTRACT FROM AUTHOR]

Abstract Livestock wastewater is rich in nutrients but may contain antibiotics and antibiotic resistance genes (ARGs). Their discharge to watercourses or soil may result in proliferation of ARGs. Irrigation with wastewater appears to be the most feasible option of disposing of it. One efficient irrigation technology used in arid regions is alternate-furrow irrigation (AFI) by alternately drying part of the plant roots for a prolonged period to physiologically reduce transpiration without compromising yield. However, the extent to which AFI with wastewater influences the concentration of antibiotics and spread of ARGs in soil is poorly understood. The purpose of this paper is to investigate how AFI using swine wastewater alters antibiotic kinetics and ARGs abundance under different irrigation rates, using pepper as the model plant. We examined three AFI treatments using 50%, 65% and 80% of the amount of water employed in sufficient conventional furrow irrigation. Each treatment had a groundwater irrigation control. The results showed that antibiotic concentrations and relative ARGs abundance in the top 20 cm of soil did not increase with the irrigation amount, although they were higher than those in the groundwater-irrigated soils. The relative ARGs abundance in the soil was modulated by irrigation amount and reducing the irrigation amount in AFI reduced ARGs dispersion only in rhizosphere. When the soil moisture was close to field capacity, ARGs were more abundant in rhizosphere than in non-rhizosphere, possibly because the rhizosphere is rich in microbes and increasing antibiotic concentrations due to an increase in irrigation rate favors antibiotic-resistant microbiome in competing for substrates. These, however, were not mirrored in the relative ARGs abundance in the roots. These results have important implications as it revealed that reducing the input of antibiotics and ARGs into soil with AFI does not necessarily reduce ARGs proliferation. Graphical abstract Unlabelled Image Highlights • First study of alternate-furrow irrigation effects on ARGs in soil • Rhizosphere was more sensitive to water source than non-rhizosphere soil. • Cd had greater influence on ARGs distribution than antibiotics. • Sulfonomides had a greater influence on ARGs distribution than tetracyclines. • Reducing irrigation amount with AFI reduced ARGs dispersion only in rhizosphere [ABSTRACT FROM AUTHOR]

Uncertainty in future availability of irrigation water and regulation of nutrient amount, management strategies for irrigation and nitrogen (N) are essential to maximize the crop productivity. To study the response of irrigation and N on water productivity and economic return of maize (Zea mays L.) grain yield, an experiment was conducted at Water Management Research Center, University of Agriculture Faisalabad, Pakistan in 2015 and 2016. Treatments included of full and three reduced levels of irrigation, with four rates of N fertilization. An empirical model was developed using observed grain yield for irrigation and N levels. Results from model and economic analysis showed that the N rates of 235, 229, 233, and 210 kg ha−1 were the most economical optimum N rates to achieve the economic yield of 9321, 8937, 5748, and 3493 kg ha−1 at 100%, 80%, 60%, and 40% irrigation levels, respectively. Economic optimum N rates were further explored to find out the optimum level of irrigation as a function of the total water applied using a quadratic equation. The results showed that 520 mm is the optimum level of irrigation for the entire growing season in 2015 and 2016. Results also revealed that yield is not significantly affected by reducing the irrigation from full irrigation to 80% of full irrigation. It is concluded from the study that the relationship between irrigation and N can be used for efficient management of irrigation and N and to reduce the losses of N to avoid the economic loss and environmental hazards. The empirical equation can help farmers to optimize irrigation and N to obtain maximum economic return in semi-arid regions with sandy loam soils. [ABSTRACT FROM AUTHOR]

This study aims at discussing the effects of planting row spacing and irrigation amount on the plant growth, chlorophyll fluorescence parameters and yield of tomato, the purpose is to obtain the suitable arrangement of irrigation amount and planting row spacing for greenhouse tomato in Northwest China. The experiment was conducted in a solar greenhouse at the Green Lily fruit and vegetable cooperatives in Yangling Agricultural Hi-tech Industries Demonstration Zone in Shaanxi province from January to June in 2016. The cultivated variety of tomato in the experiment was HL2109. The treatments comprised three planting row spacing (L1(60 cm), L2(45 cm), L3 (30 cm))with 80 cm ridge distance and 35 cm plant spacing. Based on the cumulative evaporation from a 20 cm diameter pan between two irrigations (E), 0.6 E, 0.8 E, 1.0 E, 1.2 E were set as four different levels of irrigation amount, when the cumulative evaporation reached (20±3) mm, irrigation will be conduct. Twelve treatments were experimented totally and every treatment was replicated three times in randomized complete block designs. Based on the growth indexes, chlorophyll fluorescence parameters in different growth stages and the leaf area index, net photosynthetic rate of tomato plants during the critical period of yield formation, the effects of different row spacing and irrigation amount on tomato growth, photosynthetic physiological activities and yield were analyzed, and the relationship between different growth and physiological indexes with yield were studied. The results showed that tomato growth index: chlorophyll fluorescence parameters, net photosynthetic rate, yield and irrigation water use efficiency were all affected by both planting row spacing and irrigation amount in varying degrees, but there is no significant interaction between the two factors. Low planting row spacing treatment(L3) resulted in redundant plant growth and excessive LAI, thereby photosynthetic physiological activities of crop population were inhibited, finally causing lower yield and irrigation water use efficiency. Excessively low irrigation amount inhibited photosynthetic physiological activities and showed a cumulative effect of water stress with the growth period of tomato plants. By path analysis, LAI and Pn have the most direct impact on yield among the indicators, improving the Pn is an important way to increase crop yield. Plant height and stem diameter have a good regression relationship with leaf area index(P=0.004 6), plant with large stem diameter and low height has suitable leaf area index, which is beneficial to yield formation. The yield of tomato followed a downward quadratic parabola shape with the increase of irrigation amount and planting row spacing, however, when planting row spacing and irrigation amount reached 45 cm and 0.8E respectively, continuing to increase planting row spacing and irrigation amount would not significantly increase yield. Considering the irrigation water use efficiency and yield, L1-0.8E and L2-0.8E treatment were better than others. Compared with the highest yield treatment (L1-1.2E), L1-0.8E and L2-0.8E treatments can increase irrigation water use efficiency by 36.00% and 29.29% when yield reduced by only 4.28% and 9.00%. So, when the ridge distance is 80 cm and the plant spacing is 35 cm, the planting row distance selected 45-60 cm, the irrigation quantity is set to 0.8E would be the appropriate combination of irrigation amount and planting row spacing of greenhouse tomato in Northwest China. [ABSTRACT FROM AUTHOR]

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department 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 Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering 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.)

A sustainable agricultural system depends on good soil quality and crop performance. However, information is limited about the influence of long-term irrigation schedules on soil properties and crop performance on fields without crop residue incorporation or machine tillage. In this study, we investigated the changes of soil bulk density (BD), saturated hydraulic conductivity (Ksat), water-stable aggregate, soil organic matter (SOM), and total nitrogen (TN) at the depths of 0 to 5, 5 to 10, 10 to 20, and 20 to 40 cm relative to different irrigation amounts based on a 17-year-long experiment in a double-cropping system with crop residue removed and manual tillage in the North China Plain. Results showed that BD increased as the irrigation amount increased. Saturated hydraulic conductivity reached a maximum level at a moderate irrigation level. Irrigation timing also affected soil BD and Ksat. Water-stable aggregates did not show consistent trends. Soil organic matter and TN showed similar decreasing trends with increased irrigation amount. No significant relationships were found between soil physical properties and grain yield. However, SOM did affect crop production significantly. Overall, results indicated that continuous irrigation without crop residue return negatively affected soil properties and crop performance. Soil quality and crop production may benefit from a reasonable irrigation strategy and the return of crop residue to the field. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences 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.)

Based on loam soil in different design density 1.4 g/cm3, 1.5 g/cm3, 1.6 g/cm3, we had done the test of the changes relationship between the soil containing water and the soil water potential, and analyzed the soil water potential trends of the loam soil in the design of different bulk density. The results show that the value of loam soil water potential is in the range of 57 to 140 kpa under the same soil containing water (gravimetric water content 12.5%) and the design of three soil bulk density, and present that the greater the soil bulk density, the smaller the soil water potential. The changing range of them is in trend of decreasing. All of these experimental studies will be benefit to choose the suitable discharge of the dripper for drip irrigation system, and make full use of the natural energy of the soil water potential, using it as the control index of irrigation system. At the same time, these results can provides a theoretical basis further for researching on the crop root zone soil moisture migration regularity and determining the optimal soil moisture environment. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering 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.)

This study aimed to determine the effect of irrigation amount and irrigation frequency on drip-irrigated flue-cured tobacco evapotranspiration (ETa), yield, and water use efficiency. Four irrigation treatment levels were imposed: 100% IRT (fully irrigated treatment, no stress), 85% IRT, 70% IRT, RFT (rainfed treatment), and high, medium, and low irrigation frequencies were set. The relationship between irrigation volume and yield is a quadratic curve. The evapotranspiration had a positive relationship with the irrigation amount. The yield of flue-cured tobacco was the highest in 2016 (wet year), and the corresponding ETa was the smallest. The irrigation water use efficiency (IWUE) in the driest year, 2017, was lower than IWUE in the wet years 2015 and 2016, and the crop water use efficiency (CWUE) had similar results for the three years. IWUE increased with irrigation amount. The effect of irrigation frequency on CWUE was not significant. The CWUE had a positive relationship with yield. No significant differences due to irrigation frequency were found for yield.

Understanding soil water percolation in paddy fields is helpful to optimize irrigation schedule for rice production and improve water use efficiency under various irrigation practices and groundwater depths. Calibrated HYDRUS-1D model was used to simulate soil water movement and water balance in this study. We conducted scenario analyses based on the model to evaluate the combined effects of irrigation amount in an irrigation event (irrigation amount), irrigation duration, antecedent soil moisture, and groundwater depth on deep percolation (DP) in paddy fields. Results showed that during an irrigation event, there would be higher DP in paddy fields with higher antecedent soil moisture (≥−10 kPa), larger irrigation amount (7 cm) and/or free drainage in the bottom of rice root zones. We also used a classification and regression tree model to analyze the relative contribution of different factors to DP. Results indicated that antecedent soil moisture was the primary factor that contributed 46.3% of DP variation. Groundwater depth contributed 32.5% of DP variation, while irrigation amount (18.7%) and irrigation duration (2.5%) contributed least for DP variation. Furthermore, effects of these factors on DP interacted with each other. In scenario analysis, the contribution of antecedent soil moisture increased from 16.1% to 65.2% as the groundwater depth increased. When irrigation amount rose from 1 cm to 5 cm, the contributions of antecedent soil moisture increased to 77.6% from 57.1%; when irrigation amount was 7 cm, the contributions of antecedent soil moisture decreased to 46.4%. The contribution of irrigation amount rose to 55.7% from 28.4% with the increase of antecedent soil moisture, while the contributions of groundwater depth to DP showed opposite variation to irrigation amount as antecedent soil moisture altered. Based on relative contribution of these factors, optimal combinations of irrigation practices, antecedent soil moisture and groundwater depth were screened out to control DP for promoting rice growth and improving water use efficiency. [ABSTRACT FROM AUTHOR]

Under field conditions, this study investigated the influence of the irrigation amount on olive root morphology and spatial distribution. Soil samples were taken with an auger at distances of 30, 60, and 90 cm from the tree trunks in four directions. The roots were analyzed using an Epson Twain Pro root scanning system. The results indicated that under different irrigation treatments, the indicators of root morphology of different varieties showed different responses to the irrigation amount. The root length density (RLD), root surface area (RSA), and root volume (RV) of Arbosana first increased with increasing irrigation amount but then decreased; however, those of Arbequina monotonically increased with increasing irrigation amount. The root average diameter of the two varieties was inversely proportional to the irrigation amount. In the vertical dimension, the RLD and RSA of each treatment decreased with increasing soil depth and were mainly distributed in the surface soil (0-20 cm in depth). The RLD and RSA in the vertical direction (VD) of the drip irrigation belt were higher than those of the belt in the parallel direction (PD), and the range was 12% to 86%. Compared with the roots of the 0- to 20-cm soil layer, the roots of the 20- to 40-cm and 40- to 60-cm soil layers were more influenced by the irrigation amount. Horizontally, the RLD and RSA decreased with increasing radial distance. The 30-cm radial area contained most roots, the proportion of roots in this region increased with increasing irrigation capacity. The influence of irrigation quantity in the PD of the drip irrigation belt was greater than that in the VD. The results suggest that irrigation does not change the root spatial distribution pattern but does promote root growth. The two varieties had different responses to irrigation. In terms of soil moisture levels after irrigation, 75% of field capacity is appropriate for 'Arbosana', whereas 100% is advisable for 'Arbequina'. To improve water use efficiency, moisture should be irrigated within the 30-cm radial distance from the trunk, and irrigation depth is not easy to more than 20 cm. This study provides a scientific basis for the efficient water management of olive trees. [ABSTRACT FROM AUTHOR]

Key message: Growth of C. japonica under highly irrigated and N-loaded soil is noticeable because of N-induced increase of needle mass and alleviation of high irrigation-induced reduction in photosynthesis. Abstract: To clarify the combined effects of change in precipitation amount and increasing nitrogen load on Japanese forest trees, 2-year-old seedlings of Cryptomeria japonica were treated with combinations of four irrigation levels (80, 100, 120, or 140% of annual precipitation) and three nitrogen loads (15, 50, or 100 kg ha year). The 100% of annual precipitation corresponded to 1520 mm year which was the average annual precipitation in the habitats of C. japonica in Japan. High irrigation amount significantly enhanced the whole-plant dry mass of the seedlings. The N load significantly enhanced the extent of high irrigation-induced increase in needle dry mass. As a result, the irrigation-induced increase in the whole-plant dry mass was greater in the treatment with the highest N. However, increase in needle dry mass induced by high irrigation enhanced plant water consumption and caused dehydration and oxidative damage in needles, thus resulting in reduced net photosynthetic rate. The high irrigation-induced reduction in net photosynthetic rate was alleviated by N load. This alleviation was not caused by N load-induced changes in antioxidative capacity but by a N load-induced increase in ribulose 1,5-bisphosphate carboxylase/oxygenase activity. These results indicate that an increase in the whole-plant dry mass of C. japonica seedlings grown in highly irrigated and N-loaded soil was attributed to N load-induced enhancement of high irrigation-induced increase in needle dry mass and alleviation of high irrigation-induced reduction in net photosynthetic rate. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Southern Agriculture is the property of Journal of Southern Agriculture 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.)

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.)

Water and fertilizer are two important factors affecting crop growth and yield. Crop growth models are powerful tools for making irrigation and fertilization scheduling and predicting crop yield. The performance of crop models on potato under different irrigation amounts along with different N, P and K rates has been rarely evaluated, especially under drip fertigation. In this study, the accuracy of AquaCrop and DSSAT-SUBSTOR-Potato models in simulating potato growth, yield and water productivity under different drip fertigation regimes was compared. For model calibration and validation, a two-year field experiment with three irrigation levels (W 1 , 60% ET C ; W 2 , 80% ET C and W 3 , 100% ET C , where ET C was the crop evapotranspiration) and four fertigation (N-P 2 O 5 -K 2 O) rates (F 1 : 100–40–150 kg ha−1, F 2 : 150–60–225 kg ha−1, F 3 : 200–80–300 kg ha−1 and F 4 : 250–100–375 kg ha−1) was carried out in a sandy region of northwest China in 2018 and 2019. The statistical indicators showed that the AquaCrop model gave satisfactory predictions of canopy cover (R 2 ≥ 0.92, NRMSE ≤ 14.7%, d ≥ 0.96 and RMSE ≤ 10.8%), total dry matter (R 2 ≥ 0.92, NRMSE ≤ 25.0%, d ≥ 0.94 and RMSE ≤ 2.2 t ha−1), final dry tuber yield (R 2 ≥ 0.57, NRMSE ≤ 12.21%, d ≥ 0.82 and RMSE ≤ 0.83 t ha−1) and fresh tuber yield (R 2 ≥ 0.53, NRMSE ≤ 12.02%, d ≥ 0.81 and RMSE ≤ 4.91 t ha−1) in the four fertigation treatments (F 1 -F 4) under W 3 and W 2 during the two potato growing seasons. The final total dry matter and tuber yield under W 1 were over-estimated. The simulated water productivity and soil water content also agreed well with the observations (R 2 ≥ 0.91 , NRMSE ≤ 5.51%, d ≥ 0.94 and RMSE ≤ 0.48 kg m−3, and R 2 ≥ 0.40 , NRMSE ≤ 14.8%, d ≥ 0.77 and RMSE ≤ 11.5 mm). The simulation accuracy of DSSAT-SUBSTOR-Potato model was lower than that of AquaCrop model, which only showed a goodness of fit between simulated total dry matter, soil water content, tuber yield, water productivity and observations under high irrigation amount with high fertilization rate (W 3 F 4). Since the observed tuber yield increased with the increase of irrigation level (60–100% ET C) under the same fertigation rate, 120%ET C and 40%ET C were further simulated using the AquaCrop model to test the changes in tuber yield with further increased or decreased irrigation levels. The scenarios simulation showed that the tuber yield was only increased by 0.19%−1.52% under 120%ET C compared with that under 100% ET C , but 18.0% more irrigation water was consumed. Comprehensively considering water resources and tuber yield, the irrigation level of 100% ET C (W 3) along with fertigation (N-P 2 O 5 -K 2 O) rate of 200–80–300 kg ha−1 (F 3) was recommended for the sustainable potato production in the study region. The results of this study can provide guidance for the application of crop models in drip-fertigated potato. • AquaCrop and DSSAT-SUBSTOR-Potato were evaluated under various drip fertigation regimes. • AquaCrop adequately simulated the effects of irrigation and fertilization regimes on potato. • Simulation accuracy of DSSAT-SUBSTOR-potato was lower than that of AquaCrop. • 100% ET C along with N-P 2 O 5 -K 2 O rate of 200–80–300 kg ha−1 was recommenced for potato production. [ABSTRACT FROM AUTHOR]