Higher demand and cost of labor and water shortage have forced the farmers to look for an alternate method of cultivation in rice as a substitute to the existing conventional transplanting. Dry direct seeding and water seeding have emerged as better alternatives over transplanting method. These methods not only result in labor saving, but also result in significant water saving in rice. These are important adaptation strategies to the impending climate change. However, the direct seeding method is confronted with severe weed infestation and yield losses if weeds are not managed well. Against this backdrop, a field study was undertaken during kharif seasons of 2019 and 2020 to evaluate the effect of crop establishment methods and weed management practices on rice and its associated weed flora. The results demonstrated that grain yields obtained under water seeding (WS) were statistically at par with transplanting (CT), but significantly superior to dry direct seeding (DDSR). Yield attributes were significantly superior in WS as compared DDSR, but were at par with CT. Weed density followed the order of DDSR > WS > CT. With the advancement in age of the crop, sedges dominated in DDSR, whereas broad-leafweeds (BLW) dominated in WS and CT methods of establishment. All the herbicides reduced the weed density significantly as compared to weedy check. Penoxulam (PE) reduced the weed density and weed dry matter on an average by 91% and 92% at 30 DAS/DAT over weedy check, respectively. PE proved significantly superior in controlling all the sedges and grasses but was less effective against BLW. Maximum reduction in yield due to weeds was observed in weedy check (WC) (58%) and the lowest was observed in PE (3%). Application of PE @ 22.5 g ha⁻¹ under the WS method of crop establishment resulted in highest average weed control efficiency and grain yield. Full article

A field experiment was conducted to investigate the effectiveness of different herbicides for controlling wild onion (Asphodelus tenuifolius) in cumin (Cuminum cyminum L.) during the rabi seasons (2018–2019 and 2019–2020) at Agricultural Research Station, Agriculture University, Jodhpur, Rajasthan. The experiment comprised eight herbicidal weed management treatments for wild onion applied to cumin in a three-replication randomized block design. Among the herbicidal weed management treatments, early post-emergence (8 DAS) application of oxyfluorfen 200 g/ha resulted in the lowest weed density and dry matter of Asphodilus tenuifolius, with maximum weed (Asphodilus tenuifolius) control efficiency at 40 days after sowing (DAS) during both experimental years. Likewise, the highest total efficiency of weed control was recorded with the application of oxyfluorfen 200 g/ha at 8 DAS. Oxyflourfen 200 g/ha used early post emergence (8 DAS) reduced the weed index more effectively than the other herbicides. It also recorded the highest number of branches/plant, plant height, umbels/plant, umbellates/umbel, seeds/umbellates, and seed yield. However, application of oxyflourfen @ 200 g/ha 8 DAS–early POE and pendimethalin 38.7 CS 500 g/ha + oxyfluorfen @ 150 g/ha 8 DAS–early POE were statistically similar in terms of plant growth, yield, and yield attributes. The net returns (366.49 USD/ha in 2018–2019 and 175.72 USD/ha in 2019–2020) and B:C ratio (1.70 and 1.33 in 2018–2019 and 2019–2020, respectively) were also superior, with oxyfluorfen 200 g/ha applied early post emergence. Full article

To avoid competing with economical plants, weed control must be implemented with a clean and appropriate strategy. Since the efficiency of leguminous crops in biological fixation of the atmospheric N₂ is severely affected when grown under stressful conditions (the soil tested in this study was salt-affected; EC_e = 8.99 dS m⁻¹), an appropriate level of N fertilization should also be applied. Two field trials were performed in the 2018 and 2019 seasons to investigate the influences of soil-applied nitrogen (N) levels [48 (N₁), 96 (N₂), and 144 kg N ha⁻¹ (N₃)] and critical timing of weed removal (CTWR) on weed control efficiency, improving weed control, yield traits, and quality attributes in peanut (Arachis hypogaea L.). Each trial was conducted with three replicates and planned according to a split-plot in a completely randomized design. The results revealed that N levels had significant (p ≤ 0.01) variations for the dry weight of all weeds tested (narrow-leaved, broad-leaved, and total annual weeds), pods and seed weight and yields, N use efficiency, and oil and protein yields (t ha⁻¹) in peanut in both seasons. N₃ outperformed both N₁ and N₂ with respect to the above-mentioned traits, however, it decreased N use efficiency and seed oil content compared to N₁ and N₂, respectively. Dry weight of weeds and seed harvest index were significantly (p ≤ 0.01) increased, while seed oil and protein contents, N use efficiency, and yields of pods, seeds, and protein were decreased, with increased weed interference (with peanut plants) period in both seasons. In both seasons, the interaction effect of N × W (weed removal time) was significant (p ≤ 0.01) on the dry weight of weeds and peanut traits, including seed oil content, N use efficiency, and yields of pods, seeds, and protein, and their highest values were obtained with N₃ × W₆ (weed-free for the whole season). The CTWR had growing degree days (GDDs) of 221.4 and 189. These two GDDs each corresponded to 2 weeks after emergence (WAE) in both growing seasons. The critical weed-free period (CWFP) had GDDs of 1400 and 1380. These two GDDs corresponded to 9.5 and 10 WAE, respectively. The combination of CTWR and CWFP resulted in a critical period of weed control (CPWC) of 2–9.5 and 2–10 WAE in both growing seasons, respectively, for the peanut crop with an acceptable yield loss of 5%. A high positive (p ≤ 0.01) correlation was noted between oil yield and seed yield (r = 0.999 ** and 0.999 **). However, a high negative (p ≤ 0.01) correlation (r = −0.723 ** and −0.711 **) was found between dry total annual weeds and seed weight in the first and second seasons, respectively. The stepwise regression analysis revealed high significant participation of two traits (i.e., seed yield and oil content) and three traits (i.e., seed yield, oil content, and weight of seeds) in the variations in oil yield in the first and second seasons, respectively. These results recommend the use of N fertilization at a rate of 144 kg N ha⁻¹ in conjunction with keeping the soil free of weeds throughout the season to maximize peanut productivity under saline (8.99 dS m⁻¹) conditions. Full article

Crop production is a constant battle with weeds, in which weeds, generally, are victorious. Therefore, rather than channeling our efforts into the development of a “silver bullet” to control weeds, the focus should be on sustainable weed management in both natural- and agro-ecosystems. However, sustainable weed management can be a challenge in the context of global climate change. Over the past few decades, global climate change, mostly indicated by phenomena such as increased atmospheric temperature and elevated CO₂ levels, is evident due to human activities and natural events. These phenomena also affect regional/local climate, resulting in significant influences on the agricultural systems of a particular region. Rising CO₂ levels may give comparative advantages to C₃ plants through increased photosynthesis, biomass production and yield, compared to C₄ plants. Plants with C₄ photosynthetic pathways, on the other hand, are likely to benefit more from rising global temperatures than C₃ plants. Thus, the differential responses of C₃ and C₄ plants to climate change may alter crop–weed interactions and competition outcomes, most likely at the expense of the crop. Climate change will likely cause shifts in weed community compositions, their population dynamics, life cycle, phenology, and infestation pressure. Some weed species may go extinct, while some others may become more aggressive invaders. Weeds are, generally, colonizers and have some unique biological traits and ecological amplitudes that enable them to successfully dominate crops in a habitat with changed environmental conditions. Moreover, climate shifts, especially erratic rainfall and drought, may affect herbicide selectivity and efficacy or the success of bio-control agents resulting in an establishment of a mixed and complex population of C₃ and C₄ weed species adding to the complexity of weed management. Although elevated CO₂ levels will stimulate the productivity of major C₃ crops, most troublesome agricultural weeds will likely be more responsive to a rise in CO₂ than crops, and thus may dominate the agro-ecosystem. It is predicted that, as temperature rises, the majority of the C₄ weeds will flourish and will pose serious crop yield losses. Understanding and assessment of the impact of simultaneous changes in multiple climate factors and their complex interactions on crops and weeds are therefore necessary to formulate an adaptive weed management approach and build resilience. Moreover, strategic policies and strong actions need to be taken to reduce the root causes of CO₂ and other greenhouse gas emissions to minimize the impact of climate change on weed biology and management. Full article