Effectiveness of Improving Groundnut Productivity Using PGPR and Foliar Spraying with Some Micronutrients

Abstract

One of the main obstacles to the decline in groundnut production is related to micronutrient deficiency, the deficiency of which leads to significant disruption of various physiological and metabolic processes within the plant. This study aimed to investigate the response of the Bradyrhizobium-groundnut symbiosis system to inoculation either individually or combined with some rhizobacteria (a mixture of Ps. fluorescens, B. polymyxa, B. megaterium and B. circulans), foliar spraying of some micronutrients and their interactions on the nodulation pattern, growth productivity, and some chemical traits of groundnut seeds. Two factorial experiments were conducted during two successive summertime of 2021 and 2022 at Kom-Ombo Agricultural Research Station, Aswan Governorate, Upper Egypt. Where, the treatments were allocated to experimental units in a split-plot design. The results showed that uninoculated groundnut had the least nodulation features, lowest values for vegetative growth and yield parameters, and lowest shelling percentages. However, inoculation with Bradyrhizobium significantly enhanced all previous groundnut parameters. The co-inoculation strategy treatment (Bradyrhizobium and a mixture of PGPRs) showed a promotive impression in all measurements. Foliar spraying  with two levels of tested micronutrients (M1 and M2) significantly affected nodule traits, growth aspects, groundnut yield, shelling percentage, seed quality characteristics, and nutrient uptake compared to the unamended treatment (M0). In most cases, the foliar spray treatment (M1) was superior. Co-inoculation with Bradyrhizobium and PGPRs combined with any level of micronutrients was superior over all treatments and caused remarkable increases in all previous groundnut parameters. The synergistic effects of bacterial co-inoculation along with micronutrient application as foliar spray (M1 level) registered the highest values of all above tested groundnut parameters. Excess spray of micronutrients foliar nutrition (M2 level) led to an insignificant decrease compared to (M1 level), but still higher than other tested combinations and came in second rank.