North-western Indo-Gangetic Plains Research Articles

Sequential herbicide application coupled with mulch enhances the productivity and quality of winter onion (Allium cepa L.) while effectively controlling the mixed weed flora

Weed control poses substantial difficulties for winter season onion (Allium cepa L.) cultivation in the north-western Indo-Gangetic Plains, primarily due to the constrained efficacy of the existing herbicides. To address this issue, a 2-year field study was conducted to assess the efficacy of pre- and post-emergence herbicides (pendimethalin, ethoxysulfuron, imazethapyr, and quizalofop-p-ethyl) individually and in combination with crop residue mulch for weed control in winter onion. The results revealed that using herbicides or mulches in isolation did not provide satisfactory weed control. However, the integration of natural mulch with pendimethalin followed by quizalofop-p-ethyl application proved to be the most effective weed control strategy, resulting in the least reduction in bulb yield (10.3%) compared to other treatments. On the contrary, combinations of pendimethalin with ethoxysulfuron or imazethapyr showed adverse effects on the onion crop and inflicted the highest yield losses among all treatments (78.6 and 83.4%, respectively). However, the combination of pendimethalin with quizalofop-p-ethyl coupled with crop mulch resulted in season-long weed control and over 80% bulb yield (36.58 t/ha) gains compared to the weed-free condition. These findings emphasize the efficacy of combining herbicides and mulches as an integrated weed management strategy for onions. By adopting such integrated approaches, farmers could improve weed control while maintaining bulb yield and quality, reducing the risks associated with herbicide resistance, and promoting sustainable onion production in the north-western Indo-Gangetic Plains.

Controlling Phalaris minor with novel pyroxasulfone under conservation agriculture in the north-western Indo-Gangetic Plains

A field experiment was conducted during the winter (rabi) seasons of 2021–22 and 2022–23 at the research farm of ICAR-Indian Agricultural Research Institute, New Delhi to evaluate the effectiveness of pyroxasulfone in controlling resistant Phalaris minor within the maize (Zea mays L.)-wheat (Triticum aestivum L.) cropping system. The experiment consisted a split-plot design involving 3 crop establishment systems (Bed + R; ZT + R and CT + R) and 5 weed management strategies, viz. pyroxasulfone (W1); pyroxsulfone fb metsulfuron + carfentrazone (W2); Sulfosulfuron + metsulfuron (W3); UWC (W4); and WFC (W5), replicated thrice. The results from two-year analysis consistently favoured bed planting with residue, which exhibited the lowest P. minor density and total weed population compared to the other two methods with highest weed control efficiency. Among the various weed management options, the combination of pyroxasulfone fb metsulfuron + carfentrazone recorded significantly lowest P. minor density and higher weed control efficiency, similar to the weed-free check. Additionally, this treatment led to significantly higher dry matter accumulation (68.2 g/m2), ear length (12 cm), test weight (41 g) and grain yield (5.8 t/ha) compared to other herbicide treatments, underscoring its outstanding performance.

Production potential of pulse-and oilseed-based climate-resilient alternative cropping systems for diversification of rice (Oryza sativa)–wheat (Triticum aestivum) in North-western Indo-Gangetic Plains

A field experiment was conducted during 2016–17, 2017–18 and 2018–19 at the Punjab Agrcultural University, Ludhiana, India, to evaluate the economic feasibility of pulse-and oilseed-based new alternative cropping systems in comparison to rice (Oryza sativa L.)–wheat (Triticum aestivum L.) cropping system. Among the 10 cropping systems evaluated in a randomized block design on a loamy sand soil, the highest rice-equivalent yield (23.2 t/ha) was obtained in groundnut (Arachis hypogaea L.)–garden peas (Pisum sativum L.)–sunflower (Helianthus annuus L.) with highest sustainable- yield index (0.81), followed by groundnut –garden peas– spring maize (Zea mays L.) (22.5 t/ha) as significantly better than rest of the cropping systems. In comparison to conventional rice–wheat system, higher net returns as well as relative economic efficiency were recorded in 4 cropping systems, viz. groundnut–garden peas–sunflower, groundnut–garden peas–spring maize, rice–wheat–summer mungbean [Vigna radiata (L.) R. Wilczek] and mungbean–toria [Brassica rapa subsp. dichotoma (Roxb.) Hanelt]–sunflower. Maximum apparent water productivity was observed in pigeonpea [Cajanus cajan (L.) Millsp.]–chickpea (Cicer arietinum L.)– summer mungbean, whereas the maximum nutrient-use productivity was observed in groundnut–garden peas– sunflower, followed by pigeonpea–chickpea–summer mungbean and the least values were recorded in rice–wheat system. Thus, resource-conserving biointensive cropping systems, viz. groundnut–garden peas–sunflower, groundnut–garden peas–spring maize, rice–wheat–summer mungbean and mungbean–toria–sunflower can be adopted for higher productivity, profitability and sustainability.

Impact of contrasting tillage, residue mulch and nitrogen management on soil quality and system productivity under maize-wheat rotation in the north-western Indo-Gangetic Plains

The sustainability of dominant rice-wheat rotation is under threat due to numerous water-, nutrients-, weeds- and environment-related problems, mainly, due to rice cultivation in north-western Indo-Gangetic Plains (NWIGP) of India. It needs crop- and soil- appropriate management techniques with a focus on conservation agriculture (CA) that can maintain soil health which in turn is essential for long-term sustainability of intensive cereal-based systems. Thus, rice-wheat rotation may be diversified with maize as feasible substitute for rice. But, there is a dearth of comprehensive investigation on the impact of short-term CA in maize-wheat rotation, on soil quality. Hence, an attempt has been made to assess the system productivity (SP) and soil quality in a four-year-old CA-based maize-wheat rotation. Contrasting tillage as the main plot [Conventional tillage (CT), No–tillage (NT)], crop residue mulch as subplot [residue mulch (M+), no residue (M0)], and nitrogen [50 (N1), 100 (N2), 150% (N3) of recommended nitrogen dose] as sub-sub plot was laid out in split-split plot design. Soils sampled from 0–0.05, 0.05– 0.15, and 0.15–0.30 m soil layers were examined to develop a unified soil quality index (SQI) through principal component analysis (PCA) and expert opinion. The available K, P, total organic carbon (TOC), EC, bulk density (BD), dehydrogenase activity (DHA), and soil microbial biomass C (SMBC) were identified as the crucial minimum data set for SQI using PCA. Results showed that, NT and M+ plots had 10.52 and 17.39% higher mean weight diameter (MWD) than CT and M0, respectively at 0–0.05 m soil depth. NT and M+ plots increased TOC by 5.26 and 8% than CT and M0 plots, respectively in 0–0.05 m soil layer. Available K and P were found to be significantly higher in M+ plots than that of M0. NTM+ treatments improved SMBC and DHA than CTM0 treatments. The highest and lowest SQI was registered with NTM + N3 and CTM0N1, respectively. SP was significantly and positively correlated with SQI. Diversification of rice-wheat system with maize-wheat rotation following CA practices appears to have a positive impact on soil health. Therefore, CA-based maize-wheat rotation may be recommended to improve soil quality and system productivity in NWIGP region.

Combining sub-surface fertigation with conservation agriculture in intensively irrigated rice under rice-wheat system can be an option for sustainably improving water and nitrogen use-efficiency

ContextThe rice-wheat cropping system in the Indo-Gangetic plains (IGP) of South Asia has been shown to have higher productivity. However, this benefit is offset by the unsustainable over-drafting of groundwater resources. Given the growing scarcity of water, it is imperative to investigate alternative crop establishment and irrigation methods that do not rely on the conventional puddled transplanting method (PTR). ObjectiveThis study aims to assess the impact of combining conservation agriculture-CA with sub-surface drip irrigation-SSD referred to as CA+, at different nitrogen (N) doses on physiological performance, crop yield, irrigation and nitrogen use-efficiency, as well as farm profitability of rice in the north-western IGP of India. MethodA two-year field experiment was conducted to assess the effects of medium-term CA and the combination of CA with SSD (CA+) at three levels of N (0%, 75%, and 100% of the recommended dose), in comparison to PTR using recommended dose of nitrogen-RDN (120 kg N ha-1). Indicators of crop growth (under CA, CA+), i.e., biomass, grain yield, water-use, water-use efficiency (WUE), nitrogen-use efficiency (NUE), and economic analysis of rice production were evaluated and compared with PTR. ResultThe results revealed that the PTR plots produced 15% and 11% higher grain yield than CA and CA+ systems, respectively, even at 100%RDN, due to a significantly higher number of fertile tillers. However, the application of 100%RDN and irrigation through SSD resulted in a significant increase in nitrogen uptake (4.5%) and remobilization (7.5%) into the grain compared to PTR. The CA+ plots demonstrated a reduction in irrigation water usage by 1.5 and 2 times compared to the CA and PTR systems, leading to a respective increase in WUE by 1.6% and 1.8%. PTR exhibited highest net returns, while the CA+ treatment– SSD-N100 achieved the highest benefit-cost ratio. ConclusionThe combination of CA with SSD at 100%RDN offers significant benefits, including notable water saving, improved WUE, NUE and crop yield. This integrated approach presents a promising solution to address the pressing issues of food security and sustainability arising from water scarcity and groundwater depletion in South Asia. Future implicationThere is a need to increase awareness among farmers about the benefits of CA coupled with SSD i.e., CA+ , for water-intensive rice-based systems. Additionally, further research should focus on identifying ideal rice cultivars suitable for CA+ systems and determining the optimal specifications for drip lines and emitter discharge rates for diverse water-scarce agro-ecological conditions.

Long-Term Conservation Agriculture Influences Weed Diversity, Water Productivity, Grain Yield, and Energy Budgeting of Wheat in North-Western Indo-Gangetic Plains

Wheat is grown in an area totalling 31.1 million hectares in India. The North-western Indo-Gangetic Plains (IGP) constitutes the major share of area and production of wheat in India and is known as the wheat belt of India. However, sustaining wheat production under declining/lower resource-use efficiency in the existing rice–wheat cropping system has led to considerations about diversifying this system with a pigeon pea–wheat system (PWS) in the IGP of India. However, little or no information is available on the impact of CA-based PWS on weed dynamics, productivity, profitability, and resource-use efficiencies. Therefore, we studied these aspects in wheat under a long-term (~12 years) conservation agriculture (CA)-based PWS. Treatments were conventional till flatbed (CT), ZT permanent narrow beds (PNBR & PNB), broad beds (PBBR & PBB), and flat beds (PFBR & PFB) with and without residue (R) retention and different N levels (75% and 100% of the recommended N). The results showed that the Shannon–Weiner index and the Simpson dominance index were higher under the CA system in 2021–2022 than in 2010–2011 and 2015–2016, indicating a change in weed diversity over the period. Furthermore, the Sorensen similarity index showed that there was not much difference in weed diversity for 2010–2011. However, in 2015–2016 and 2021–2022 respectively, only 89% (0.89) and 62% (0.62) of weed species were common to both CT and CA systems, indicating a shift in weed species in the long-term CA system in 2021–2022. Residue retention and N dose decreased weed density at 30 days after sowing (DAS). All the CA-based (PFBR100N, PBBR100N, PNBR100N, PFBR75N, PBBR75N, and PNBR75N) treatments reduced the weed density and dry weight compared to CT at 30 DAS. Wheat grain yield and net returns increased by 11.6–14.9% and 19.4–23.8% over CT in CA treatments, of which PFBR100N and PBBR100N were superior. The PBBR100N and PBBR75N systems had water productivity significantly higher than CT. Residue retention in ZT permanent beds reduced energy productivity in CA than CT and no residue treatments. In the 12th year, CA with 75% N (PFBR75N, PBBR75N, PNBR75N) resulted in a higher partial factor productivity of N and total NPK applied. Contrast analysis showed that 75% N was comparable with 100% N on crop, water, and energy productivities and 75% N was superior to 100% N on partial factor productivity of N and total NPK. Thus, the permanent broad bed with residue and 100% N in the initial years and 75% N in later years can be adopted in the north-western IGP for better weed suppression, higher yield, profitability, and resource-use efficiency.

Long-term impact of organic and conventional farming on soil physical properties under rice (Oryza sativa)-wheat (Triticum aestivum) cropping system in north-western Indo-Gangetic plains

Long-term (13 years) impact of organic and conventional farming on soil physical properties was evaluated under a rice (Oryza sativa L.) – wheat (Triticum aestivum L.) cropping system in a sandy clay loam soil at New Delhi. The treatments included unfertilized control (T1), conventionally managed (T2) and five organic treatments (T3: FYM @ 10 t/ha to rice and wheat, T4: SGM for rice and LGLM for wheat, T5: SGM + BGA for rice and LGLM + Azotobacter for wheat, T6: SGM + FYM for rice and LGLM + FYM for wheat, and T7: SGM + FYM + BGA for rice and LGLM + FYM + Azotobacter for wheat). The application of organic amendments had positive influence on soil physical properties such as saturated hydraulic conductivity (Ks), field capacity (FC) and permanent wilting point (PWP), plant-available water capacity (PAWC), water holding capacity (WHC), distribution of aggregate size fractions, bulk density (Db), and porosity in the 0-15 and 15-30 cm soil layer. A favourable effect of organic amendments was also found on soil strength (at depth 0-70 cm). Even, values related to these properties were significantly affected by the kinds of organic amendments. But, T1 and T2 had no improvement in soil physical properties over the organic ones. Value of Ks decreased with increase in soil depths. T7 and T3 were superior in Ks to other treatments for 0-15 and 15-30 cm soil depths. Volumetric moisture content at FC (θFC) and PWP (θWP) increased with addition of organic amendments and got varying response due to the kinds of organic amendments or their combinations. θFC and θWP were decreased substantially under T1 and T2, because of no addition of organic inputs. As a result of θFC and θWP, PAWC had also signified an improvement under the influence of different organic amendments over T1 and T2. Generally (for both depths), PAWC of T3, T6 and T7 were 17-26% more than T1, T2, T4 and T5. WHC of upper soil layer (0-15 cm) was greater for organic amended plots than plots devoid of organic inputs and lower values were recorded for 15-30 cm soil layer. WHC of T3, T7 and T6 was highest in comparison to plots amended only with (without FYM) green manure, BGA or Azotobacter as well as T1 and T2 for both depths (0-15 and 15-30 cm). A better soil aggregation was observed under organic amended plots for large and small macro-aggregates (LM - >2 and SM-0.25-2 mm) in both soil depths. Lowest value of Db with highest percentage of pore space was noted under T7 than other treatments in both soil layers. Soil strength was significantly lower in organic amended plots than T1 and T2. This study clearly indicated that application of organic inputs especially FYM, improved the soil physical properties, which resulted in better soil aggregation, porosity and soil moisture retention.

Challenges and technological interventions in rice-wheat system for resilient food-water-energy-environment nexus in North-western Indo-Gangetic Plains: A review.

Rice (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping system in north-western Indo-Gangetic Plains performed a crucial role in the national food security. However, thewidespread andintensive cultivation of this systemhas led to serious problems such asdeclining groundwater table (~1meteryear-1) with sharp increase in number of districts under over-exploitation category, residue burning, higher greenhouse gases emission and herbicide resistance in weeds, causing stagnant crop productivity and lesser profitability. In this review article, an attempt has been made to discuss the major issues pertaining to intensive rice-wheat cultivation amidst climate vagaries and futuristic approach to address these challenges. Different tillage- and crop-specific recommendations such as adoption of direct seeded rice, diversification with lesser resource guzzling crops such as maize (Zea mays L.) at least on the periodic manner especially in light-medium soils, inclusion of summer legumes and alternative tillage systems (permanent beds and zero tillage with residue retention) have been suggested to address these issues. However, crop performance under these techniques has been found to belocation, soil and cultivar specific. The absence of aerobic tailored genotypes and weeds have been identified as the major constraints in adoption of direct seeded rice. The integrated strategies of conservation tillage, crop breeding program and resource conserving region- and soil-specific agronomic measures with crop diversification would be helpful in tackling the sustainability issues. It requires future efforts on developing crop genotypes suited to conservation tillage, effective weed control strategies and trainings and demonstrations to farmers to switch from conventional rice-wheat system to alternative cropping systems.

Impact of weed management methods on growth, productivity and economics of spring maize under north-western Indo-Gangetic plains of India

Impact of weed management methods on growth, productivity and economics of spring maize under north-western Indo-Gangetic plains of India

Climate adaptive rice planting strategies diverge across environmental gradients in the Indo-Gangetic Plains

Abstract The timing of rice planting has a profound influence on the productivity of the rice-wheat cropping pattern in the Indo-Gangetic Plains (IGP), a system that provides the foundation for food security in South Asia. Nevertheless, strategies for adaptive rice planting in a rapidly changing climate are not well established. In this ex-ante analysis, regional gridded crop model simulations are deployed to investigate the impact of different rice planting strategies on system level productivity, resilience, and environmental benefits. Our results suggest that synchronizing rice planting dates with the monsoon onset substantially outperforms farmer practice (+41%) and static state recommendations in the Eastern IGP. However, planting long-duration rice with the monsoon onset is ineffective in the Northwestern IGP since the later arrival of the monsoon increases the probability of cold damage to rice and terminal heat stress in wheat. Here, fixed planting dates (+12.5%) or planting medium duration varieties at monsoon onset (+18%) performed best. We conclude that resilient and productive rice planting strategies must account for interannual weather variability and divergent climate conditions across sub-regions in the IGP.

Co-implementation of conservation tillage and herbicides reduces weed and nematode infestation and enhances the productivity of direct-seeded rice in North-western Indo-Gangetic Plains

Direct-seeded rice (DSR) can be a resource-efficient alternative to puddled transplanted rice (PTR), but weeds and nematodes pose severe challenges. Conservation agriculture (CA)-based DSR may inhibit/influence weeds/nematodes, which can be further intensified by adopting better weed control. Hence, this experiment was undertaken. Five CA-based DSR practices involving zero tillage, residue retention, brown manuring, and superimposed with four weed control/herbicide options were compared with PTR in a split-plot design replicated three times. All DSRs encountered more weeds and plant parasitic nematodes (PPNs) than PTR. Root-knot nematodes (RKN) infested five among 14 weeds present in rice and was first time found in Dinebra retroflexa. A CA-based zero till (ZT)DSR+ mungbean residue – ZT wheat + rice residue – ZT mungbean+wheat residue system reduced weeds significantly. It reduced RKN galls in Echinochloa colona, Echinochloa crusgalli, and rice plants by 72, 58, and 56%, respectively. In soil too, RKN and other PPNs, namely, Tylenchorhynchus brevilineatus and Pratylenchus thornei were reduced by 39%, 32%, and 26%, respectively, which gave a 6.3–22.7% higher yield in this CA practice than other DSRs. Pyrazosulfuron-ethyl, cyhalofop-butyl, and bispyribac-Na applied sequentially reduced weeds and PPNs, increased rice yield by 176.1%, and were at below detectable levels in soil, rice grains, and straw, and were safe for rotational crops. The above ZT-based triple cropping with residue supplemented with herbicides through better weed and nematode control would be an alternative to PTR in the North-wester Indo-Gangetic Plains of India and in similar agroecologies of the tropics/sub-tropics. This study would help farmers and policymakers to design integrated weed and nematode management modules using tillage, crop residue, and herbicides/pesticides for higher DSR yield and income.

Interpretable machine learning methods to explain on-farm yield variability of high productivity wheat in Northwest India

The increasing availability of complex, geo-referenced on-farm data demands analytical frameworks that can guide crop management recommendations. Recent developments in interpretable machine learning techniques offer opportunities to use these methods in agronomic studies. Our objectives were two-fold: (1) to assess the performance of different machine learning methods to explain on-farm wheat yield variability in the Northwestern Indo-Gangetic Plains of India, and (2) to identify the most important drivers and interactions explaining wheat yield variability. A suite of fine-tuned machine learning models (ridge and lasso regression, classification and regression trees, k-nearest neighbor, support vector machines, gradient boosting, extreme gradient boosting, and random forest) were statistically compared using the R 2 , root mean square error (RMSE), and mean absolute error (MAE). The best performing model was again fine-tuned using a grid search approach for the bias-variance trade-off. Three post-hoc model agnostic techniques were used to interpret the best performing model: variable importance (a variable was considered “important” if shuffling its values increased or decreased the model error considerably), interaction strength (based on Friedman’s H-statistic), and two-way interaction (i.e., how much of the total variability in wheat yield was explained by a particular two-way interaction). Model outputs were compared against empirical data to contextualize results and provide a blueprint for future analysis in other production systems. Tree-based and decision boundary-based methods outperformed regression-based methods in explaining wheat yield variability. Random forest was the best performing method in terms of goodness-of-fit and model precision and accuracy with RMSE, MAE, and R 2 ranging between 367 and 470 kg ha −1 , 276–345 kg ha −1 , and 0.44–0.63, respectively. Random forest was then used for selection of important variables and interactions. The most important management variables explaining wheat yield variability were nitrogen application rate and crop residue management, whereas the average of monthly cumulative solar radiation during February and March (coinciding with reproductive phase of wheat) was the most important biophysical variable. The effect size of these variables on wheat yield ranged between 227 kg ha −1 for nitrogen application rate to 372 kg ha −1 for cumulative solar radiation during February and March. The effect of important interactions on wheat yield was detected in the data namely the interaction between crop residue management and disease management and, nitrogen application rate and seeding rate. For instance, farmers’ fields with moderate disease incidence yielded 750 kg ha −1 less when crop residues were removed than when crop residues were retained. Similarly, wheat yield response to residue retention was higher under low seed and N application rates. As an inductive research approach, the appropriate application of interpretable machine learning methods can be used to extract agronomically actionable information from large-scale farmer field data. • Data-driven agronomic research requires new analytical and methodological approaches. • Machine learning methods were used to disentangle complex relationships in farmer field data. • Model-agnostic tools were used to derive agronomic interpretations. • Residue management and N application rate were important management variables for wheat yield. • Residue management interacted with other practices to explain wheat yield variability.

Impact of Conservation Agriculture on Wheat Growth, Productivity and Nutrient Uptake in Maize–Wheat–Mungbean System

Conservation agriculture (CA) involving minimum mechanical soil disturbance, permanent soil cover with crop residue mulch and diversified crop rotation, plays a crucial role in sustainable crop production. A field experiment was conducted at ICAR-Indian Agricultural Research Institute, New Delhi during rabi seasons (November–April) of 2018–19 and 2019–20 in wheat involving maize-wheat-mungbean system to assess the effects of CA on crop productivity, nutrient uptake and profitability. Results showed that CA-based practices with residue retention resulted in higher yield as well as economic benefits when compared to conventional tillage (CT). Wheat yield parameters in CA were greater than in CT. The CA-based practices improved wheat grain and straw yield to the tune of 7.2–27.1% and 5.7–20.6%, respectively compared to CT practice. The CA-based practices with residue retention with 100% N registered 9.7% higher cost of cultivation, but resulted in 24.3–35.1% higher net returns than CT. Among CA-based practices, the plots under permanent broad bed with residue with 100% N (PBB+R+100N) resulted in ~27% higher wheat grain yield compared to CT. The PBB+R+100N plots also had considerably greater nutrient uptake and net returns than CT plots. The CA practice involving PBB+R+100N was found to be more productive, remunerative and could potentially boost up the wheat productivity and profitability under maize-wheat-mungbean system in north-western Indo-Gangetic Plains of India.

Agrometeorological evaluation of mustard (Brassica juncea) under organic production in North Western Indo-Gangetic Plains

A field experiment was conducted to evaluate agrometeorological parameters associated with seed yield of Indian mustard (Brassica juncea L.) varieties in an organic production system. During the study, significant variation was recorded in crop phenophases, growth, yield attributes, and seed yield of mustard. Varieties NRCHB-101 and Pusa Mustard-25 have taken significantly minimum days to commence flowering (46–48 days) and attaining physiological maturity (89–90 days). Variety RGN-48 being at par with RH-406 and RGN-229, recorded significantly higher plant height, while RGN-229 recorded the significantly highest biomass accumulation at all the growth stages. Varieties RH-406, Pusa Bold, and DRMRIJ-31 recorded significantly higher seeds per siliqua (16.2–16.5), whereas significantly higher test weight was recorded in Pusa Bold (6.3 g) and DRMRIJ-31 (6.0 g). In seed yield, variety RH-406 (1.97 t/ha) and DRMRIJ-31 (1.42 t/ha) were found significantly highest and lowest, respectively. A significant positive correlations of mustard seed yield was noticed with biomass accumulation at 30 DAS (r=441**), 60 DAS (r=0.614**), 90 DAS (r=0.620**) and biological yield at harvest (r=0.496**). Contrary to test weight, seeds per siliqua had shown a positive effect (r=0.266*) on the seed yield of the mustard. Seed yield of mustard was also influenced by some agrometeorological indices with correlation coefficients (r) of mean minimum temperature at flowering and physiological maturity and mean maximum temperature at physiological maturity were -0.207*, -0.249*, and -0.241*, respectively. Net solar radiation and cumulative temperature difference at physiological maturity also had significant and positive effects on the seed yield of mustard.

Adoption and Impact of Wheat variety HD 3086: An analysis using structural equation modeling

Varietal development plays a crucial role in improving the overall yield of a crop and the impact assessment of a particular variety is essential to support this statement. Present study was carried out in North-Western Indo-Gangetic Plains (Punjab, Haryana and Western Uttar Pradesh) in India during 2017–18 to observe the response on the yield with the adoption of newly developed yellow rust resistant wheat variety HD 3086. The Structural Equation Model (SEM) was used to establish a relationship between the rate of adoption and factors affecting the same. Households (1000) were surveyed through random sampling for the study. Punjab was found to have the highest adoption rate amongst the 3 states followed by Haryana. This study has observed an increasing trend in coverage of farm area under HD 3086 in Punjab and Haryana. However, in Uttar Pradesh creating awareness among the seed companies and Krishi Vigyan Kendra (KVK) centres was found imperative for the multiplication of HD 3086.

Rice yield gaps and nitrogen-use efficiency in the Northwestern Indo-Gangetic Plains of India: Evidence based insights from heterogeneous farmers’ practices

A large database of individual farmer field data (n = 4,107) for rice production in the Northwestern Indo-Gangetic Plains of India was used to decompose rice yield gaps and to investigate the scope to reduce nitrogen (N) inputs without compromising yields. Stochastic frontier analysis was used to disentangle efficiency and resource yield gaps, whereas data on rice yield potential in the region were retrieved from the Global Yield Gap Atlas to estimate the technology yield gap. Rice yield gaps were small (ca. 2.7 t ha−1, or 20% of potential yield, Yp) and mostly attributed to the technology yield gap (ca. 1.8 t ha−1, or ca. 15% of Yp). Efficiency and resource yield gaps were negligible (less than 5% of Yp in most districts). Small yield gaps were associated with high input use, particularly irrigation water and N, for which small yield responses were observed. N partial factor productivity (PFP-N) was 45–50 kg grain kg−1 N for fields with efficient N management and approximately 20% lower for the fields with inefficient N management. Improving PFP-N appears to be best achieved through better matching of N rates to the variety types cultivated and by adjusting the amount of urea applied in the 3rd split in correspondance with the amount of diammonium-phosphate applied earlier in the season. Future studies should assess the potential to reduce irrigation water without compromising rice yield and to broaden the assessment presented here to other indicators and at the cropping systems level.

Physiological evaluation of growth and yield variation of mustard (Brassica juncea) varieties under organic products in North-Western Indo-Gangetic Plains

A field experiment was conducted for two years to analyze the physiological basis of variation in the growth and yield of popular mustard varieties under organic production. Twelve mustard varieties of varied duration and agroclimatic suitability were evaluated in a randomized complete block design. Results revealed that varieties NRCHB-506, RH-406, and RGN-229, being at par, registered significantly maximum leaf area index, photosynthesis rate, and chlorophyll content at all the crop growth stages, i.e., 30, 60 and 90 DAS. During both the intervals, i.e., 30-40 and 80-90 DAS, variety RH-406 followed by RGN-229 registered maximum crop growth rate, whereas,in NRCHB-101, the lowest crop growth rate was observed. At each crop growth stage, photosynthesis rate has a significant positive correlation with leaf area index, chlorophyll content, crop growth rate during 30-40 and 80-90 DAS. Varieties Pusa Mustard-25 (5.8) and Pusa Mustard-26 (5.7) recorded significantly higher primary branches plant-1. However, varieties Pusa Tarak, RH-406, and RGN-229 recorded the significantly highest number of secondary branches plant-1. Being at par, varieties NRCHB-506, RH-406, RGN-229, and Pusa Bold recorded a significantly higher number of silique plant-1, seed yield,and stover yield than other varieties. The seed yield was found significantly and positively correlated with the crop growth rate at 80-90 DAS (r=0.600**), chlorophyll content at 90 DAS (r=0.558**), and silique plant-1(r=0.518**).Therefore, it is inferred that varieties like RH-406, RGN-229, and NRCHB-506 are suitable to grow under organic nutrient management in the prevailing agro-climatic conditions.

Status of herbicide resistance in Phalaris minor in wheat in Haryana

Herbicide resistance in little seed canary grass (Phalaris minor Retz.) in wheat is the major sustainability issue, which puts the rice-wheat (R-W) system in north-western Indo-Gangetic Plains (IGP) under serious threat. To assess the resistance level, a questionnaires based survey with a systematic approach was conducted during rabi 2017-18 in five districts (Yamuna Nagar, Kaithal, Karnal, Fatehabad and Rohtak) of Haryana. The study revealed that at present, farmers of Haryana are closely back to square one, similar to the situation of herbicide resistance in P. minor like 1990's and currently, no herbicide is satisfactorily effective against resistant P. minor. Farmers are using every possible combination of herbicides in a hit and trial way. In 2017-18, half of the farmers (50%) went for the second spray, 13% applied the third spray, and even 3% of farmers opted for the fourth spray. The same pattern followed in the case of herbicide dose; in 2017-18, 38% of farmers opted for 2-4 X-dose, 16% of farmers for 4-6 X-dose, 3% of farmers for 6-8 X-dose, and even one percent farmers applied 8-10 X-dose. Negative relationship between percent control with higher dose (X) (Chi-Square value 72.560a, DF = 12 and p = <0.001) and multiple sprays (Chi-Square 67.076a, DF = 8 and P = <0.001) recorded during 2017-18 also indicates strong chances/evidences of herbicide resistance development.

Net Ecosystem Exchange of Carbon Dioxide in Rice-Spring Wheat System of Northwestern Indo-Gangetic Plains

Rice growing under anaerobic conditions followed by spring wheat under an aerobic environment differentially impact the net ecosystem exchange (NEE) of carbon dioxide (CO2) in rice-wheat systems of the north-western Indo-Gangetic Plains (IGP). This is the first estimation of the NEE in a rice-spring wheat sequence via the eddy covariance technique in the north-western Indo-Gangetic Plains, which was partitioned into gross primary productivity (GPP) and ecosystem respiration (RE) and correlated with the environmental variables. Higher CO2 uptake of −10.43 g C m−2 d−1 was observed in wheat during heading as compared to −7.12 g C m−2 d−1 in rice. The net uptake of CO2 was 25% lower in rice. The average daily NEE over the crop season was −3.74 and −5.01 g C m−2 d−1 in rice and wheat, respectively. The RE varied from 0.07–9.00 g C m−2 d−1 in rice and from 0.05–7.09 g C m−2 d−1 in wheat. The RE was positively correlated with soil temperature at 5 cm depth (0.543, p < 0.01) in rice and with air temperature (0.294, p < 0.01) in wheat. The GPP was positively correlated with air temperature (0.129, p < 0.05) and negatively correlated with vapor pressure deficit (VPD) (−0.315, p < 0.01) in rice. In wheat, GPP was positively correlated with air temperature (0.444, p < 0.01) and soil moisture (0.471, p < 0.01). The rate of GPP over the crop duration was nearly the same in both rice and wheat, however, the RE was higher in rice as compared to wheat, thus, the ratio of cumulative RE/GPP was 0.51 in rice and much lower at 0.34 in spring wheat. Rice contributed 46% and 43% to the annual totals of RE and GPP, respectively, while spring wheat contributed 36% and 51%. The NEE of CO2 was higher in spring wheat at −576 g C m−2 d−1 as compared to −368 g C m−2 in rice. Thus, while estimating the carbon sink potential in the intensively cultivated northern IGP, we need to consider that spring wheat may be a moderately stronger sink of CO2 as compared to rice in the rice-wheat system.

Productivity and Profitability of Fodder Cowpea Cultivars under Various Zinc Management Practices in IGP of India

Background: Soils of North-Western Indo-Gangetic plains (IGP) are deficient in zinc content which may lead to lower forage yield of cowpea. Henceforth, the adequate supply of zinc either through soil or foliar spray and selection of suitable cultivar of cowpea could enhance the fodder productivity.Methods: A field experiment was laid out in factorial randomized block design during Kharif season, 2019 to assess the effect of different zinc management practices (control; 10 kg ZnSO4; 20 kg ZnSO4; 0.5% ZnSO4 foliar spray at 20 DAS; 0.5% ZnSO4 foliar spray at 20 and 40 DAS) on productivity and profitability of cowpea cultivars (C-152; MFC-08-14; MFC-09-1) and post-harvest fertility status of soil.Result: Cowpea cv. C-152 showed the highest growth attributes, green fodder yield, nutrient content as well as uptake and net returns. Among different zinc management practices, the application of 20 kg ZnSO4 as basal application or 0.5% ZnSO4 foliar spray at 20 and 40 DAS recorded significantly highest growth, green fodder yield, nutrient content as well as uptake and net returns. Significantly highest soil OC, available N, K and Zn were also noted under these treatments. It is inferred that cowpea cv. C-152 and application of either 20 kg ZnSO4 as basal or 0.5% ZnSO4 as foliar spray at 20 and 40 DAS were found the most productive and profitable approach and sustained the soil fertility status.