Synergistic effects of herbicides and gibberellic acid on wheat yield and quality

Gibberellic acid (GA₃) is commercially applied to stimulate the growth and productivity of various agricultural crops. However, its impact on the yield and chemical properties of wheat under weed stress is still unclear. In this investigation, the influence of weed control (sulfosulfuron (sulfo-s), florasulam 7.5% + flumetsulam 10% (derby), pyroxsulam (pallas), and untreated check) and GA₃ (0, 100, and 200 mg/L) treatments on the narrow-leaved weed (i.e., Avena fatua L.) and broad-leaved weeds as well as yield and chemical properties of wheat (cv. Sakha 94) was explored. The findings showed that the wheat plants were infested by seven weed species. Such weeds were notably controlled using herbicidal treatments, particularly annual sowthistle (Sonchus oleraceus L.) (94.1 and 92.0%) and field binder (Convolvulus arvensis L.) (91.5 and 93.6%) were very highly susceptible to pallas herbicide in both seasons. Likened to control group, the application of GA₃ (especially at 200 mg/L) or pallas herbicide observably decreased the dry weight of wild oat (Avena fatua L.) and broad-leaved weeds, which contributed positively to the increase of plant height, No. of spikelet's/spike, 1000-grain weight, and grain yield (P < 0.05) in both seasons. Moreover, spraying of sulfo-s herbicide maximized spike length of wheat plants (16.0 cm) in the 2^nd season, whereas plots treated with derby had the highest spike weight (7.64 and 7.17 g) and No. of grains/spike (62.0 and 58.8) in two seasons. Furthermore, the maximal grain yield was recorded following the synergistic spraying of pallas and GA₃ at 200 mg/L (7278 kg/ha in the 1st season) as well as sulfo-s and GA₃ at 200 mg/L (6935 kg/ha in the 2nd season). Relative to control, significant increases in protein (by 46.99 and 50.47%) and nitrogen content (by 46.93 and 50.54%) were also noticed after the use of derby and 200 mg/L GA₃ in 1^st and 2^nd season, respectively (P < 0.05), implying the improvement in the quality of wheat grains. Most remarkably, Pearson's correlation demonstrated that the reduction in Avena fatua L. and broad-leaved weeds was accountable strongly for 66 to 96% of the enhancement in yield and chemical properties of wheat under the application of herbicides and GA₃ treatments. The current findings may be very relevant in guiding farmers in the selection of suitable agronomic treatments (i.e., herbicides and GA₃) that may maximize wheat yield and quality.