Interactive Application of Zinc and Herbicides Affects Broad-leaved Weeds, Nutrient Uptake, and Yield in Rice

Due to the ability of weeds to deplete nutrients from the soil, crop plants become subjected to a complex of abiotic and biotic stresses. Thus, the interactive effects between one of the most important micronutrients, i.e., zinc (Zn) and some herbicides on weeds, rice yield and nutrient uptake were investigated. The experiment was carried out in a randomized complete block design in factorial arrangement using three replicates. Ten combinations of two Zn levels (without Zn, Zn−, and with Zn, Zn+) as well as four herbicides (halosulfuron–methyl, bentazon, azimsulfuron, pyrazosoulfuron–ethyl), and unweeded treatment were investigated. Findings clarified that application of halosulfuron–methyl herbicide whether with Zn− or Zn+ were the effective combinations for decreasing weed biomass. Halosulfuron–methyl and pyrazosoulfuron–ethyl had similar impact either with Zn− or with Zn+ resulted in minimum values of K uptake by weeds. The increases in grain yield ha−1 due to the application of halosulfuron–methyl, pyrazosoulfuron, azimsulfuron, and bentazon reached 13.4, 15.9, 21.3, and 24.8%, respectively, under Zn+ greater than Zn−. Halosulfuron–methyl x Zn+ was the promising interaction treatment for increasing P, K, and Zn uptakes by rice. Correlation coefficient showed that fertile panicle number, fertile grain number, rice N and K uptakes, weed biomass, and weed P uptake were the most closely associated traits with grain yield. Our study proved that there is a positive correlation between Zn and the applied herbicides in rice. Zn application alleviated the herbicidal pressure (abiotic stress) and decreased weed harmful impacts (biotic stress) on rice plants. Thus, it should be focused on the complementary effect between Zn and applied herbicides in breeding programs for generating new rice genotypes which are efficient in Zn utilization and tolerant to herbicides.