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Weed management in upland rice under subtropical climate with high rainfall is challenging. The diverse weed flora in upland rice ecosystem emerges in several flushes, necessitating sequential application of herbicides. A 4-year study conducted in Meghalaya (950 m above sea level), India indicated that sequential application of Cyhalofop butyl [2-{4-(4-cyano-2-fluorophenoxy) phenoxy} propionic acid, butyl ester (R)], a grass weed killer high efficacy low volume herbicide applied 80 g ha−1 at 25 days after sowing (DAS) and 2,4-D, a broadleaf weed killer herbicide applied 0.75 kg ha−1 at 35 DAS was effective for weed control and produced significantly higher grain yield (3572 kg ha−1) of rice with the highest weed control efficiencies than other treatments. Application of Pretilachlor followed by (fb) 2,4-D or Fenoxaprop-p-ethyl fb 2,4-D yielded significantly higher chlrophyll (chl) a, chl b and total leaf chl content compared with other herbicides at 90 DAS. The highest net energy (111,443 MJ ha−1), energy profitability and benefit:cost ratio was recorded with sequential application of Cyhalofop butyl and 2,4-D. Thus, sequential application of Cyhalofop butyl and 2,4-D could provide a sustainable weed management option in upland rice under high rainfall conditions in the Eastern Himalayas, India. [ABSTRACT FROM AUTHOR]

Context: Crop production in Eastern Himalaya is constrained by combined effects of soil acidity and moisture deficit during post monsoon under a changing climate. Aim: This study aimed to identify potential buckwheat genotypes and stress mechanisms in hill environments of Meghalaya (India). Method: Field and microcosm experiments were conducted to study field performance, genotypic variability and physio-morphological efficiency in buckwheat. Key results: Substantial genetic variability for shoot length (30.3–110 cm), crop canopy distribution (3.0–7.5 number of primary branches), leaf area retention (15.7–60.2 cm2/two leaves), 1000 seed weight (16.2–34.7 g) and seed yield (0.088–1.31 metric tonne (MT)/ha) was observed. Mean grain yield of buckwheat genotypes was 0.446 MT/ha whereas IC13411, IC24298 and IC37305 produced significantly higher seed yield (1.31, 1.28 and 1.14 MT/ha, respectively) accounting to 1.93, 1.87 and 1.67 times higher than average yield (0.680 MT/ha). Genotypes like IC42416, EC323730 and EC218784 have lower crop yields (0.8, 1.02, 0.93 MT/ha respectively). Interestingly, few high yielders (IC13411 and IC24298) exhibited higher photosynthetic rate (46.1 and 32.3 μmol/m2.s), increased stomatal conductance (311.0 and 326.2 mmol/m2.s), leaf chlorophyll (2.47 and 2.55 mg/g fresh weight (FW)) and carotenoids (95 and 106.3 μg/g FW). Chlorophyll a and b ratio (3.3 and 3.0) and total chlorophyll to carotenoids (4.2 and 4.0) were higher in high yielders (IC13411 and IC24298) compared to other low yielders. Conclusions: Robust root systems, stomatal structure and higher cuticle wax ideally enhanced water use efficiency (WUE) and drought tolerance in high-yielding buckwheat genotypes. Implications: IC13411 and IC24298 are promising for enhanced productivity in the mountainous ecosystem of Meghalaya. Buckwheat is a potential but lesser known crop, with wide adaptability and multiple utility, cultivated under resource poor and marginal soils of mountainous Eastern Himalaya. Our results indicate significant genetic variability for physio-morphological traits responsible for moisture stress tolerance on hill slopes of Meghalaya. Identified high-yielding buckwheat genotypes (IC13411 and IC24298) with increased stress tolerance could be promising for enhanced crop productivity and food security under fragile mountainous ecosystem of Meghalaya (India). [ABSTRACT FROM AUTHOR]