Using Plant Growth-promoting Fungi (PGPF), as a Biofertilizer and Biocontrol Agents against Tetranychus cucurbitacearum on Nubian Watermelon (Citrullus lanatus L.)

Abstract

Plant growth-promoting fungi (PGPF) have attracted considerable interest as biofertilizers and biocontrol due to their multiple beneficial effects on plant quantity and quality as well as their positive relationship with the ecological environment. The objective of this study was to determine the efficacy of different concentrations 25, 50, 75 and 100% from cultural filtrate of Trichoderma viride and T. harzianum to induce the two-spotted spider mite, Tetranychus cucurbitacearum (In vitro), and their ability to improve the growth dynamics of Nubian watermelon plants in field experiment during two growing summer seasons of 2017 and 2018.
 In general the effect of tested concentrations of T. viride were non effective on egg deposition by adult females after five days from treatment, while in T. harzianum, the concentration 75% was the most effect than the other concentrations. Also, egg hatchability % decreased with increased of two egg age (1 – 2 day old) at treatment by concentrations 25 and 50% of both fungal. In field experiment, the test compound (vertimec) was the more effective against egg stage of spider mite T. cucurbitacearum than motile stages of both T. viride and T. harzianum treatments. Also, plants inoculated with T. harzianum showed increases in vegetative growth parameters included numbers of leaves, Leaf dry weight, stem length and numbers of branches and biochemical analysis of leaves included chlorophyll content and percentages of NPK at 30 and 60 days from sowing during both seasons compared to uninoculated control plants. Also, enzymes activities, treatment T2 (inoculated with T. viride) recorded the highest values at all growth stages, which recorded 155.77, 257.29 and 114.62 mg TPF g-1 soil day-1 for dehydrogenase and 113.79, 201.03 and 115.24 mg NH4+- N g-1 soil d-1 for urease at 30, 60 and harvest during 2017 growing season, respectively. The same trend was observed in total count of fungi during both seasons.
 For fruit yield, T. viride (T2) had significantly the highest number of fruits per plant, number of seeds per fruit, fruit weight (g) and dry weight of 100 seeds (g) which recorded 1.92, 273.07, 1126 g and 16.29 g as compared to untreated control treatment, which attained 1.21, 185.08, 526.66 g and 14.41 g at 2017 season, respectively. Therefore, these results reflected to increase fruit yield (Kg/m2), seed yield (g/m2) and weight of yield (ton fed.-1) during both seasons.