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The crop yield can be affected by many factors, including various levels of weed presence. Therefore, we conducted a study to evaluate the effect of time of weed removal in combination with planting pattern and pre-emergence-applied herbicides on maize yield and yield components in 2015, 2016 and 2017. The experiments were designed in a split–split plot arrangements with three replications, which consisted of the two main plots (standard/conventional and twin-row planting pattern), two subplots (with and without pre-emergence herbicide application) and seven sub-subplots (seven weed removal timings). In the dry season of 2015, maize yield was much lower (413–9045 kg ha⁻¹) than in the wet 2016 seasons with yields of 5759–14,067 kg ha⁻¹ across both planting patterns. Yield and yield components were inversely correlated with the time of weed removal. The application of pre-emergence herbicides delayed the critical time for weed removal (CTWR), which ranged from V4 to V10 and from V3 to V11 for standard and twin-row planting patterns, respectively. Herbicides also protected various yield components, including 1000 seeds weight and number of seeds per cob. Full article

Increasing evidence on environmental and economic benefits has raised farmers’ interest in adopting alternative, less intensive soil management practices. To evaluate the influence of weed-competitive ability in response to a different tillage regime, a field study was conducted in maize under humid Central European climatic conditions in Slovenia. This study was established as a split-plot arrangement with three tillage practices (TPs) as the main plot: conventional (CN), conservation (CS), and no tillage (NT); this was combined with glyphosate application and the weed removal timing as the subplot. The weed removal timings were at the V3, V6, V9, V15, and R1 maize stages, with weed-free and weed season-long monitoring. The beginning and the end of the critical period of weed control (CPWC), based on a 5% maize yield loss rate, were determined by fitting the four-parameter log-logistic equations to the relative maize dry grain yield. The weed dry biomass from maize germination until the R1 growth stage in the NT TP was consistently lower than that in the CN and CS TP. Moreover, the NT TP resulted in a shorter CPWC (39 days after emergence (DAE)) compared to the CN (57 DAE) and CS (58 DAE). The results of CTWR (critical timing of weed removal) showed that less intensive tillage operations in the CS resulted in an earlier need for weed control (V2 and 23 DAE) compared to the CN (V3 and 39 DAE) and NT (V3 and 40 DAE). Our study suggests that the intensive tillage operations performed in the CN TP and the pre-sowing use of non-selective burndown herbicide in the NT delay the CTWR by more than 2 weeks, thus reducing the need for early post-emergence herbicide application in maize. Full article

The escalating scarcity of irrigation water, transplantation of rice on light-textured soils and labour cost acted as major drivers for the transition towards direct-seeded rice (DSR) cultivation from the conventionally flooded transplanting system. Despite these advantages, DSR is a challenge in light texture soil due to heavy weed infestation and a slight decline in crop yield. The weeds compete for nutrients and have an adverse effect on the growth and yield of crops. Hence, to assess the removal of macro and micronutrients by weeds and direct-seeded rice, a field experiment was carried out on sandy loam soil for two consecutive Kharif seasons (2018 and 2019). Three treatments from rice, namely: DSR under zero tillage (DSR-ZT), DSR under conventional tillage (DSR-CT) and DSR under reduced tillage (DSR-RT) were taken as main plots with three tillage treatments in wheat, namely: Conventional tillage without rice straw (CTW-R), Zero tillage without rice straw (ZTW-R) and Zero tillage with straw as mulch using Happy Seeder (ZTW+R) as subplots, replicated thrice. Among the rice establishment methods, DSR-RT showed an edge in terms of rice grain and straw yield (6.18 and 8.14 Mg ha⁻¹, respectively) as well as macro- and micronutrient uptake by rice. Under management practices, ZTW+R proved as an efficient strategy in terms of yield and nutrient uptake by crops. The contribution of weeds towards biomass production was maximum under the ZTW-R (9.44%) treatment followed by DSR-ZT (7.72%). The nutrient budgeting showed that macro- and micronutrient removal by weeds was minimum under reduced tillage (24.51 and 50.35%, respectively), whereas it was 21.88 and 44.87% when wheat was grown under conventional tillage without rice straw. In overall, the research study concluded that weeds on an average remove 25.65 % macronutrients (N, P, K) and 51.47% of micronutrients (Zn, Cu, Fe and Mn) in DSR under rice-wheat cropping system. Full article

Determining the critical time for weed removal (CTWR) is essential for the development of an integrated weed management plan. Therefore, field experiments were conducted to evaluate the effects of two planting patterns (standard and twin-row) with and without PRE-applied herbicides on CTWR in corn. Experiments were laid out in a split-plot arrangement with two main plots: (i) standard row planting (SRP) that is 70 cm wide, and (ii) twin-row planting (TRP) with 50 cm distance between each set of double rows. Each main plot was divided into two sub-plots (with and without PRE herbicides). The sub-sub-plots consisted of seven weed removal timings for PRE herbicides, and tank mixes were utilized (S-metolachlor (1.44 kg a.i. ha⁻¹) + terbutylazine (0.75 kg a.i. ha⁻¹)). The CTWR without PRE herbicides was similar in both the SRP and TRP systems, where it was around the V1 to V2 (16 to 19 d after emergence (DAE)) growth stages. The use of PRE-applied herbicides delayed CTWR in SRP to the V4 to V10 (25 to 58 DAE) stages and up to the V11 (60 DAE) stage in TRP. These results clearly indicate that PRE herbicides are important for protecting corn yields regardless of the planting pattern. In more meteorologically favorable seasons (sufficient heat and precipitation) in both sowing systems, corn plants produce their biological maximum with the fact that over the number of plants per unit area (SRP = 80,000 plants ha⁻¹, TRP = 93,900 plants ha⁻¹) provide higher yields in variants with PRE herbicides, and thus the advantage of the TRP system can be justified. 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