Preliminary Investigation on Crop Growth, Physiology, and Yield of Rice under Partial Root-Zone Irrigation

Rice is a staple food predominantly consumed by more than half of the global population. Water deficit is a crucial threat to produce rice globally. Prevailing water-saving techniques for rice can reduce water inputs but are not widely adopted due to the high yield penalty. Partial root-zone irrigation (PRI) is an innovative water-saving technique that allows simultaneous wet and dry areas within the root zone. We hypothesized that optimized PRI improves the water use and reduces the yield penalty of rice. A split root experiment was conducted on rice grown in pots with six defined PRI treatments, that is, PRI1, PRI2, PRI3, PRI4, PRI5, and PRI6. Half of the root system was wetted and alternated between halves with one- (PRI1), two- (PRI2), three- (PRI3), four- (PRI4), five- (PRI5), and six- (PRI6) day intervals. Conventionally irrigated rice plants where the whole root zone of rice was wetted and grown in the nonsplit pot were maintained and considered as control. Control and PRI treatments were irrigated based on 100% potential evapotranspiration demand (ETc). In particular, one PRI treatment (PRI3) showed a remarkable increase in active roots and leaf photosynthesis (PN) by wet and dry cycles within the root zone. Distinctive shoot responses of rice under PRI indicated enriched physiological responses for superior water productivity. The third-day-interval partial root-zone irrigation (PRI3) and conventional irrigation had similar leaf water potential (Ψleaf), while PRI3 had higher grain yield than conventional treatment and higher root surface area that may have compensated for the moderate level of stress in PRI. The finding that PRI scheduled at three-day intervals (PRI3) was superior to conventional irrigation for a single rice plant is promising and needs to be tested and adapted to field conditions

Data from: Evaluation of drip irrigation system for water productivity and yield of rice

The use of drip irrigation in upland rice cultivation is a contemporary water-saving strategy however, inadequate evidence available related to consequential changes in water productivity on rice yield. The effects of distinctive drip irrigation treatments viz., differences in lateral distances [0.6, 0.8 and 1.0 m], dripper discharge rates [0.6 and 1.0 litre per hour], irrigation methods [surface and sub-surface] and the conventional aerobic rice production system (control) on, physiology and water productivity of rice were studied during summer 2012 and 2013. Grain yield significantly increased in sub-surface drip irrigation method laid out at 0.8 m lateral distance and in 1.0 litre per hour (lph) discharge rate (5389 kg ha-1) compared with control irrigation method (4181 kg ha-1). This treatment mount up dry matter partitioning, leaf photosynthesis as well as root oxidizing power. In addition, drip irrigation in aerobic rice production system had twice the water productivity and stimulates longer roots with higher density compared with control irrigation method. The sub-surface drip irrigation system with drippers/laterals of 0.8 m distance with flow rate 1.0 lph, in aerobic rice production system is a cost-effective method and had the potential to save water (27.0 %) without compromising for grain yield in comparison to control irrigation method. This could be the promising technology to be recommended for aerobic rice production system

Dry matter partitioning coefficient,water budget and evapotranspiration data observed in drip irrigated rice cultivation

Dry matter partitioning coefficient (PC) of aerobic rice (Conventional) compared to drip irrigation with aerobic rice treatments. Crop evapotranspiration calculated for the cropping period. Total Water Applied (TWA: mm), Irrigated Water (IW: mm) and Effective Rainfall (ER: mm) of aerobic rice cultivated under drip and conventional practice

Groundwater Quality Status of the Parambikulam Aliyar Palar Basin, Tamil Nadu, India Using RS and GIS Techniques

The dependency of ground water is rising day by day. The ground water gets recharged mainly through rainfall. Thirty five water samples were collected from Parambikulam Aliyar Palar basin from open wells, bore wells and dug cum bore wells and analysed for chemical properties such as pH, Electrical Conductivity, cations and anions for two years duration (2020 and 2021) at three months interval (summer, winter, southwest monsoon, northeast monsoon) and analysed for the quality parameters. T Electrical conductivity values were ranged from 0.3 to 5.19 dsm-1, 0.29 to 6.80 dsm-1 0.3 to 6.84 dsm-1 and 0.64 to 4.17 dsm-1 during south west, north east, winter and summer seasons of 2020, respectively. The salt content was slightly increased during winter and summers seasons as compared to south west and north east. he samples were classified under USSL classification.  Most of the samples come under medium salinity class (C2) (48.57%) followed by low salinity class (C1), high salinity class (C4) and very high salinity class (C3) with 28.57, 14.29 and 8.57 per cent respectively in all the seasons. Majority of the samples exhibit there is no permeability hazard. Salinity persists in the basin and possibility of salt accumulation in irrigation pipes observed from LSI values. Using remote sensing and GIS technique, the mapping was done for the groundwater quality of PAP basin. The variations in the ground water quality of the basin are directly positively correlated with rainfall pattern and geology of the basin. For effective utilization of saline water in the basin, management strategies were formulated and field experiments were conducted in the farmer’s holdings in the sampling area of the basin

Field Validation of the DNDC-Rice Model for Methane and Nitrous Oxide Emissions from Double-Cropping Paddy Rice under Different Irrigation Practices in Tamil Nadu, India

Two-year field experiments were conducted at Tamil Nadu Rice Research Institute, Aduthurai, Tamil Nadu, India, to evaluate the effect of continuous flooding (CF) and alternate wetting and drying (AWD) irrigation strategies on rice grain yield and greenhouse gas emissions from double-cropping paddy rice. Field observation results showed that AWD irrigation was found to reduce the total seasonal methane (CH4) emission by 22.3% to 56.2% compared with CF while maintaining rice yield. By using the observed two-year field data, validation of the DNDC-Rice model was conducted for CF and AWD practices. The model overestimated rice grain yield by 24% and 29% in CF and AWD, respectively, averaged over the rice-growing seasons compared to observed values. The simulated seasonal CH4 emissions for CF were 6.4% lower and 4.2% higher than observed values and for AWD were 9.3% and 12.7% lower in the summer and monsoon season, respectively. The relative deviation of simulated seasonal nitrous oxide (N2O) emissions from observed emissions in CF were 27% and −35% and in AWD were 267% and 234% in the summer and monsoon season, respectively. Although the DNDC-Rice model reasonably estimated the total CH4 emission in CF and reproduced the mitigation effect of AWD treatment on CH4 emissions well, the model did not adequately predict the total N2O emission under water-saving irrigation. In terms of global warming potential (GWP), nevertheless there was a good agreement between the simulated and observed values for both CF and AWD irrigations due to smaller contributions of N2O to the GWP compared with that of CH4. This study showed that the DNDC-Rice model could be used for the estimation of CH4 emissions, the primary source of GWP from double-cropping paddy rice under different water management conditions in the tropical regions.Peer Reviewe

Drought Tolerance of Mungbean Is Improved by Foliar Spray of Nanoceria

In crops, drought stress reduces the photosynthetic rate and gamete function through oxidative damage. Earlier studies showed that nanoceria possesses an antioxidant property; however, the ability of nanoceria to alleviate drought-stress-stimulated oxidative damage in pulse crops has not been studied. Therefore, experiments were conducted to assess the impacts of nanoceria on drought-induced oxidative damage in mungbean [Vigna radiata (L.) Wilczek]. We hypothesize that foliar application of nanoceria under drought stress can scavenge the excess produced reactive oxygen species (ROS) due to its inherent properties which could result in increased photosynthesis and reproductive success of mungbean. Three experiments were conducted under well-watered and limited-moisture conditions. The traits associated with oxidative damage, photosynthesis, reproductive success, and yield were recorded. Results showed that for mungbean, the optimum concentration of nanoceria for foliar spray was 100 mg L−1. Field and pot culture experiments showed that foliar application of nanoceria under drought decreased the superoxide radical content (29%), hydrogen peroxide content (28%), and membrane damage (35%) over water spray. Nanoceria increased the photosynthetic rate (38%), pod-set percentage (16%), and seed weight m−2 (44%) in drought-stressed plants compared to control plants. The increased photosynthetic rate by nanoceria spray under drought stress is associated with lesser oxidative damage and stomatal limitation caused by nanoceria’s inherent ROS-scavenging ability. Hence, foliar application of nanoceria at the rate of 100 mg L−1 under drought stress could increase mungbean seed yield per plant through increased photosynthetic rate and pod-set percentage

Mitigation Potential and Yield-Scaled Global Warming Potential of Early-Season Drainage from a Rice Paddy in Tamil Nadu, India

Water-intensive systems of rice cultivation are facing major challenges to increase rice grain yield under conditions of water scarcity while also reducing greenhouse gas (GHG) emissions. The adoption of effective irrigation strategies in the paddy rice system is one of the most promising options for mitigating GHG emissions while maintaining high crop yields. To evaluate the effect of different alternate wetting and drying (AWD) irrigation strategies on GHG emissions from paddy rice in dry and wet seasons, a field experiment was conducted at the Tamil Nadu Rice Research Institute (TRRI), Aduthurai, Tamil Nadu, India. Four irrigation treatments were included: One-AWD (one early drying period), Two-AWD (two early drying periods), Full-AWD (wetting and drying cycles throughout the rice season), and CF (continuous flooding). Different rice varieties were also tested in the experiment. In this study, we emphasized one factor (irrigation effect) that affects the dependent variable. The results show that early AWD treatments reduced methane (CH4) emissions by 35.7 to 51.5% in dry season and 18.5 to 20.1% in wet season, while full-AWD practice reduced CH4 emissions by 52.8 to 61.4% compared with CF. Full-AWD in dry season not only significantly reduced CH4 emission during that season, it also resulted in the decline of the early season emission in the succeeding wet season. Global warming potential (GWP) and yield-scaled GWP were reduced by early or full season AWD in both rice seasons. The GWP value from nitrous oxide (N2O) was relatively low compared to that from CH4 in both rice seasons. Rice yield was not affected by irrigation treatments although varietal differences in grain and straw yields were observed in both rice seasons. This study demonstrated that early season water managements are also effective in reducing CH4 and total GHG emissions without affecting rice yield