Water-saving Treatments Research Articles

The Impact of Water-Saving Irrigation on Rice Growth and Comprehensive Evaluation of Irrigation Strategies

To explore the effects of different water-saving treatments on rice plant growth and select suitable water-saving irrigation strategies for aerobic rice varieties, we conducted relevant field experiments from June to October 2023 at Jiangsu Runguo Agricultural Development Co., Ltd., China, which is located in a north subtropical monsoon climate where the soil is alkaline sandy loam. Four water treatments were set up, including the control of local conventional irrigation (CK, without water stress), mild water-saving treatment (W1, 20% more water saved than CK), moderate water-saving treatment (W2, 30% more water saved than CK), and severe water-saving treatment (W3, 40% more water saved than CK). The experiment results showed that rice plant heights were inhibited and leaf chlorophyll contents increased under all water-saving treatments compared to CK. Among them, the MDA content in paddy leaves under the W1 treatment decreased, while the activities of SOD and POD were enhanced and the membrane lipid peroxidation capacity of rice was also enhanced. Meanwhile, the results showed that the rice yield and quality under the W1 treatment significantly improved. Based on those experiments, a comprehensive evaluation of rice plant height, chlorophyll content, grain yield, yield components, and rice quality was conducted using the TOPSIS entropy weight method. It was preliminarily concluded that the suitable irrigation scheme for south and central Jiangsu was 20% water-saving irrigation compared with CK. In summary, under the premise of maintaining the economic yield of rice cultivation, an appropriate water irrigation plan helped save water resources and promote rice growth.

Plant Physiological Performances, Plant Growth, Grain Yield and Methane Emission of Rice (Oryza Sativa L.) in Response to Water Management as Adaptation Strategy for Climate Change

Continuously flooded rice systems are a major contributor to the greenhouse gases (GHG) emissions in the agriculture sector in Malaysia. Intermittent irrigation has been recommended to replace conventional rice water management to save water and reduce GHG emissions without compromising rice yields. This study was conducted in two growing seasons at Malaysia’s largest rice granary area to determine the effectiveness of different water management practices on conserving water, mitigating GHG and maintaining rice grain yields. Three water management treatments were continuous flooding (CF), saturated and wet conditions from transplanting to heading and flooding until maturity (S-F) and continuous saturated and wet conditions (CS). The results showed that S-F and CS reduced water inputs between 15.0-16.8% and 32.0-34.0% as compared to CF, respectively. Water-saving treatments mostly did not significantly affect the plant's physiological performance, plant growth parameters, growth rate, grain yield and yield parameters. The results indicated that soil saturated and wet conditions provided adequate soil moisture content for the plant’s requirement similar to flooding conditions. Maintaining soil at saturated and wet conditions during the vegetative stage reduced 24.18-39.76% of methane emissions. However, maintaining soil at saturated and wet conditions throughout the growing season reduced 34.52-55.08% of methane emissions. In conclusion, intermittent irrigation could be an effective adaptation technique for simultaneously saving water and mitigating GHG while maintaining high rice grain yields in rice cultivation systems.

Magnetized Seeds and Structured Water: Effects on Resilience of Velvet Bean Seedlings (Mucuna pruriens) under Deficit Irrigation

A custom-built water generator supplied structured water (SW) for applying the deficit irrigation treatments to velvet bean plants (Mucuns pruriens). The objectives of the study were to 1) determine the effects of magnetized seed treatment on velvet bean plants, 2) determine the effects of magnetized and hydroxylated water treatments on velvet bean plants, and 4) determine the effects of deficit irrigation, using three soil moisture levels, on velvet bean plants. The optimal water-saving treatment was magnetized seeds plus 10 MT + HWT. This treatment had a 226% increase in transpiration and a 22% increase in water vapor concentration in the intercellular airspace for the low soil moisture watering schedule. The three study factors in the optimal seed and water treatment had a synchronistic effect for enhancing metabolic efficiency by increasing whole plant WUE by 87% and carbon assimilation efficiency by 66% in the low soil moisture schedule. Plants irrigated with SW water and grown from magnetized seeds had enhanced resilience to high water stress conditions by maintaining adequate levels of biologically structured water. The rapid deactivation of a suite of highly interconnected defense activities in the optimal seed and water treatments implies that the plants exhibit macroscopic coherence properties. Coherence at the macroscopic level resulted in complex synchronization between metabolic efficiency, plant health, and deactivation of a suite of regulatory defenses in plants exposed to high water stress.

Mitigating growth-stress tradeoffs via elevated TOR signaling in rice

Rice production accounts for approximately half of the freshwater resources utilized in agriculture, resulting in greenhouse gas emissions such as methane (CH4) from flooded paddy fields. To address this challenge, environmentally friendly and cost-effective water-saving techniques have become widely adopted in rice cultivation. However, the implementation of water-saving treatments (WSTs) in paddy-field rice has been associated with a substantial yield loss of up to 50% as well as a reduction in nitrogen use efficiency (NUE). In this study, we discovered that the target of rapamycin (TOR) signaling pathway is compromised in rice under WST. Polysome profiling-coupled transcriptome sequencing (polysome-seq) analysis unveiled a substantial reduction in global translation in response to WST associated with the downregulation of TOR activity. Molecular, biochemical, and genetic analyses revealed new insights into the impact of the positive TOR-S6K-RPS6 and negative TOR-MAF1 modules on translation repression under WST. Intriguingly, ammonium exhibited a greater ability to alleviate growth constraints under WST by enhancing TOR signaling, which simultaneously promoted uptake and utilization of ammonium and nitrogen allocation. We further demonstrated that TOR modulates the ammonium transporter AMT1;1 as well as the amino acid permease APP1 and dipeptide transporter NPF7.3 at the translational level through the 5′ untranslated region. Collectively, these findings reveal that enhancing TOR signaling could mitigate rice yield penalty due to WST by regulating the processes involved in protein synthesis and NUE. Our study will contribute to the breeding of new rice varieties with increased water and fertilizer utilization efficiency.

Application of water-saving treatments reveals different adaptation strategies in three Iranian melon genotypes

Melon is a major horticultural crop in Iran, where it is grown in semi-arid areas in irrigated fields. Concerns about future water security stimulate the development of water-saving irrigation practices, which requires a better understanding of melon physiology under reduced water supply. To this end, one variety of muskmelon, “Samsoury”, and two varieties of the Dudaim group, “Birjand” and “Kerman”, were grown in pots in a greenhouse with three water management treatments, consisting in refilling soil water to field capacity at different intervals: three days (T3), six days (T6) and nine days (T9). Leaf water status declined when longer refilling intervals were applied, but all genotypes maintained the same leaf turgor pressure irrespective of the treatment. Turgor was maintained both through osmotic adjustment (OA) and change in cell wall elasticity. Samsoury showed the highest OA in T3 and T6, while variation in cell wall elasticity was more evident in Birjand and Kerman. Samsoury showed also the highest photosynthesis rate (An) and stomatal conductance (gs) in T3 and T6, but the three genotypes exhibited similar values in T9. In the Dudaim-types An and gs declined linearly as soon as water potential started to decrease, while Samsoury was able to keep gas-exchange parameters stable down to a water potential value of –11.5 bars, to steeply decrease thereafter. Finally, Samsoury had the least reduction in biomass allocated to epigeic part, and allocated a higher proportion of biomass to roots in response to water restriction. From all the results, it is concluded that Samsoury performs better when water-saving treatments allow low to moderate water stress, thanks to its anisohydric-like behaviour, consisting in a looser coupling of stomatal closure with water potential, which ensures higher carbon accumulation under fluctuating water supply. The Dudaim-types showed instead a rather more conservative behaviour, typical of isohydric plants, which privilege water loss avoidance even at low water restriction levels, at the cost of carbon assimilation and growth.

Effects of water-saving irrigation on the residues and risk of polycyclic aromatic hydrocarbon in paddy field

The effects of different water-saving modes on PAHs residue and risk, field environment conditions and enzyme activities in paddy field were investigated in a field experiment plot in Laoyaba, Nanjing, China. Results showed that (1) water-saving treatment affected greatly the ΣPAHs in water and soil. The order of ΣPAHs residue in surface water and groundwater in farmland is as follows: dry fields<water-saving paddy field<flooding irrigation paddy field. The ΣPAHs in water during rice tillering stage were obviously higher than that in rice booting stage and milky stage, and the percentage of high-ring PAHs gradually reduced in water. (2) The residue of ΣPAHs in soil in flooding irrigation paddy field (534.4±186.7ng/g) were more than water-saving irrigation (454.3±128.1ng/g) and dry cultivation paddy field (430.2±143.4ng/g), and the ΣPAHs in dry field gradually decreased with the increase of water furrow number in farm. (3) When compared with flooding irrigation (337.87ng/g), water-saving (228.39ng/g) and dry cultivation (206.62ng/g) could obviously decrease the residue of ΣPAHs in rice tissues (35%–55%), generally the concentration of ΣPAHs in leaf>root>stem>rice grain. (4) Water-saving irrigation evidently decreased soil ecological risk (up to 55%–73%) and rice carcinogenic risk (up to 30%–45%) caused by PAHs compared with flooding irrigation. Water-saving irrigation could also reduce the Total Toxic Equivalency Concentration of PAHs in rice grain up to 50% relative to flooding irrigation. (5) The significant negative correlations were observed between the residual PAHs and the activities of laccase and dioxygenase (p<0.019), and the physical and chemical indexes (temperature, redox potential and dissolved oxygen of field, p<0.041). The changes of field environment conditions and enzyme activities induced by moisture control may be the main key factors affecting PAHs residue in water, soil and rice.

Impact of Deficit Irrigation on Yield and Chemical Properties of Soybean Seeds in Temperate Climate

Summary The goal of this research is to determine the effects of different levels of water deficit (I100: full irrigation, I65: 35% deficit, I40: 60% deficit and I0: no irrigation) on yield and chemical composition of soybean [Glycine max (L.) Merr.] grown in Srem region of Serbia. Water deficit significantly affected the yield and chemical composition of soybean seeds. The lowest (1.63 t/ha) and the highest (3.21 t/ha) seed yields were obtained from I0 and I65 treatments, respectively. Furthermore, the highest protein (1092 kg/ha) and oil (563 kg/ha) yields were observed in I65 treatment. Lower and higher irrigation levels from I65 decreased the protein and oil yields. Our data indicated that irrigation generally increased K, P, Mg, Mn, Cu, Zn and B concentrations and decreased Ca and Fe concentrations in soybean seed. It was clearly observed that full-watered treatment (I100) provided no potential benefit in terms of soybean yield and chemical composition. For higher economic yield and good nutritional quality, water-saving treatment I65 could be suitable in soybean management in Srem region of Serbia as in other regions with similar soil and climate conditions.

Effect of different supplemental irrigation strategies on photosynthetic characteristics and water use efficiency of wheat

Water resource scarcity has been increasingly becoming a threat to wheat (Triticum aestivum L.) production in North China Plain. Thus, a water-saving irrigation strategy should be urgently developed. We conducted a 2-yr field experiment to examine the effects of supplemental irrigation (SI) on the photosynthetic characteristics and water use efficiency (WUE) of wheat. This study employed two SI strategies: A quota SI using 60 mm water at jointing and anthesis stages (W1) and soil moisture testing SI (W2), which brings the target relative soil water content of 0-40 cm soil layer to 70% field capacity at jointing and anthesis stages. A non-irrigated treatment (W0) was used as control. Results showed that W2 significantly improved the water uptake in 80-160 cm soil layer compared with W1. Moreover, flag leaf photosynthetic rate, stomatal conductance, and transpiration 14-28 d after anthesis were highest in W2 successively followed by W1 and W0, and the difference was significant. Dry matter (DM) at maturity, DM accumulation post-anthesis and its contribution ratio to grain were significantly higher in W2 than in the other treatments. 13CO2 labeling results indicated that W2 promoted δ13C-photosynthate accumulation in grain. In 2012-2013 growing season, the grain yield increased by 56.05% and 5.74% and WUE increased by 26.17% and 6.34% in W2 compared with those in W0 and W1, respectively. In 2013-2014 growing season, the grain yield increased by 41.82% and 5.90% and WUE increased by 28.24% and 13.03% in W2 compared with those in W0 and W1, respectively. Therefore, W2 is a high-yield and water-saving treatment.

Effect of Water and Nitrogen Fertilizer Coupling on the Yield and Panicle Architecture of Japonica Rice in Cold Area

This thesis has listed rice as the research object, and by way of water treatment (water-saving treatment and CK treatment) and nitrogen-fertilizer treatment (N0, N1, N2, N3, N4), to analyze the effects of water and nitrogen fertilizer coupling on the yield and panicle architecture of rice. Results show that compared with CK, water-saving irrigation is more effective in promoting the yield. Under N-fertilizer treatment of N1, N2 and N3, the rice yield was increased by more than 10%; while under N0 and N4, the yield difference was not significant. With the increased apply of Nitrogen, under the two watering means, the yield both showed a tendency of firstly increase and later decrease. The yield hit the highest point in water-saving irrigation under N3, followed by water-saving irrigation under N2, and CK under N3.Under N2 and N3, the yield increased in water-saving irrigation was mainly contributed by the increase of the second rachis branches. The yield was increased by 30.69% and 30.37% under N2 and N3 separately. With water-saving irrigation, the yield under N3 is more than that under N2, this is mainly contributed by the increase of the grain number per panicle and the thousand seed weight. Under N3, the yield difference was not significant in either watering treatments, but water-saving irrigation has increased the average value of yield traits. Analysis of the panicle architecture has revealed that compared with CK, water-saving irrigation is more effective in increase the rice yield, which was mainly realized by the significant increase in the number of second rachis branches.

Yield and quality of sweet corn under deficit irrigation

The present study was conducted to determine the effects of different irrigation levels (I100: full irrigation; I85: 15% deficit; I70: 30% deficit; I55: 45% deficit and I40: 60% deficit) on yield and yield components, sugar and protein content of fresh sweet corn during the years of 2011 and 2012. Experiments were carried out in a randomized complete-block design with three replications.The lowest and the highest plant water consumptions (Et) were found in I40 (240–406mm) and I100 (348–504mm) treatments in both years. Water deficit affected on maize fresh ear yields, yield components, quality and water use efficiencies. The lowest fresh ear yields (11515.7 and 10952.3kgha−1) were determined in I40 treatments in both years, respectively. The highest fresh ear yields (14857.7 and 14712.7kgha−1) were obtained from I100 treatments in 2011 and 2012 years, respectively.Maize fresh ear yields were significantly affected by water deficits. Low irrigation levels decreased the ear yields. However, it was clearly observed that I70 treatment could be a water-saving treatment without a significant decrease in yield. In addition, the highest protein content and sugar amount was also observed in I70 treatment. I70 treatment seems to have lowest impact on yield and higher quality for sweet corn.

Physiological and morphological traits related to water use by three rice (Oryza sativa L.) genotypes grown under aerobic rice systems

We compared the plant growth, stomatal conductance (gs), leaf water content (LWC), and root length density (RLD) of Oryza sativa L. ssp. japonica cv. Sensho (traditional upland), ssp. indica cv. Beodien (traditional upland), and ssp. japonica cv. Koshihikari (improved lowland) under two aerobic rice systems [well-irrigated (WI) and water-saving (WS) treatments]. Irrigation water was applied every 2 days from 21 to 68 days after sowing (DAS) and everyday thereafter in WI treatment and it was applied when soil water potential at 15 cm depth reached −15 kPa from 21 to 68 DAS and every 2 days thereafter in WS treatment to impose repetitive water stress. WS treatment used 35% less water than WI. Leaf area index (LAI) and shoot dry weight (SDW) were the lowest for Koshihikari in both treatments and the ratio of LAI and SDW in WS treatment to that in WI treatment was the lowest in Koshihikari. This indicates that aerobic cultivation was not suitable for Koshihikari even under well-irrigated conditions and that the effect of repetitive water stress was the most serious in Koshihikari. Midday gs of Sensho and Beodien in WS treatment were affected by irrigation, whereas that of Koshihikari was low and stable. LWC of Koshihikari was smaller than those of upland genotypes in both treatments. LWC of upland genotypes in WI and WS reached maximum and minimum values at predawn and evening, respectively, and recovered at night, but LWC of Koshihikari in WS treatment did not recover at night. RLD of upland genotypes was higher than that of Koshihikari, but no significant differences were observed among treatments. These results indicate that genotypic difference of physiological traits under aerobic conditions (both WI and WS) was caused by the genotypic difference of water uptake capacity, which can be partly caused by the RLD. In Koshihikari, however, the LWC difference between treatments can not be explained only by the RLD. Further studies will be needed to clarify physiological mechanism responsible for the water uptake capacity of roots in aerobic rice systems.

Rice production with less irrigation water is possible in a Sahelian environment

We investigated the possibility of saving irrigation water in rice production in a Sahelian environment with different nitrogen rates and weed control treatments. A series of field experiments was conducted at Ndiaye (shallow water table, dry and wet season) and at Fanaye (deep water table, wet season) in Senegal with four irrigation treatments, involving three water-saving regimes using alternate wetting and drying (AWD) and a flooded control, and three weed management treatments. This was followed by two experiments with the same four irrigation treatments in combination with three nitrogen (N) application rates, at the same locations. Hence four irrigation regimes were tested over three seasons. Between 480 and 1060 mm of irrigation water was used in the water-saving treatments compared with 800–1490 mm in the flooded-rice treatment. Rice yields ranged from 2.3 to 11.8 t ha −1 in the water-saving treatments, whereas in the flooded control the yields ranged from 3.7 to 11.7 t ha −1. In the wet season (WS), the treatments in which AWD was applied during part of the season resulted in the highest yields at both sites. In the dry season (DS), the continuously flooded treatment out-yielded other treatments, with the exception of AWD in Fanaye. At the Ndiaye site, the control of weeds increased yields from on average 2.0 to 7.4 t ha −1 in the DS and from 1.4 to 4.9 t ha −1 in the WS. No weed control in combination with AWD during the vegetative stage reduced yields to below 1.0 t ha −1. However, when weeds were controlled, crop yields obtained with a combination of AWD and flooding were comparable with those obtained in fully flooded plots receiving the same weed management at both sites in the 2005 WS. Increasing rates of N significantly increased grain yield. Internal N efficiency was poorer at Ndiaye than at Fanaye suggesting that yields in Ndiaye are constrained by other factors than N. In Ndiaye, agronomic N use efficiency was smaller in the AWD treatments compared with fully flooded conditions. This study demonstrates that it is possible to save irrigation water and improve water productivity in rice grown in a Sahelian environment. An irrigation regime for rice that starts as conventional (flooded), and then changes to AWD can save water with little or no yield loss, while maintaining low weed pressure and efficient use of N.