Response of Snap Bean Grown under High Temperature Conditions to Mycorrhizae and Trichoderma Inoculation, Along with Glycine Betaine and Trehalose Foliar Treatments

The growing challenges of high-temperatures have necessitated cultivating crops like Phaseolus vulgaris during late dates to bridge the gap between supply and demand. This study aimed to investigate the effects of mycorrhizae and trichoderma inoculation, along with foliar spray of glycine betaine and trehalose on the growth performance, oxidative-activity and green pod yield of Phaseolus vulgaris variety Bronco under high-temperature conditions. Experimental treatments include the combined inoculation of mycorrhizae at 500 g feddan-1 and trichoderma at 1ℓ feddan-1, mycorrhizal alone, trichoderma alone, and control without additives, in addition to foliar spray of combined glycine betaine at 200 ppm and trehalose at 500 ppm, glycine betaine alone, trehalose alone, and control with tap water. The results demonstrated significant improvements in the growth performance, leaf content of chlorophyll and carotene and green pod yield components of snap bean treated with combined soil and foliar treatments under high-temperature conditions. Specifically, the inoculation of mycorrhizae plus trichoderma and spraying with glycine betaine and trehalose led to enhanced plant height, number of leaves and branches plant-1, and fresh and dry weight plant-1, and increased leaf chlorophyll and carotene contents and pod yield while decreasing peroxidase and catalase activities and proline level. Inoculation of mycorrhizae and trichoderma, plus spraying glycine betaine and trehalose can be used as a promising practice for enhancing the tolerance of snap bean to high-temperature stress by improving growth performance, increasing leaf content of chlorophyll and carotene and increasing pod yield.