Morpho-physiological and Biochemical Variability in Greengram [Vigna radiata (L.) Wilczek] Varieties for Mungbean Yellow Mosaic Virus (MYMV) Resistance under Natural Field Conditions

Abstract

Background: Mungbean yellow mosaic virus (MYMV) is economically most important disease of greengram reducing grain yields by 20-70%. Whiteflies and thrips are the most important insect pests which transmit the viral diseases MYMV and LCV respectively. The host plant resistance to MYMV disease in greengram genotypes has a great importance. The morpho-physiological and biochemical traits play an important role in host plant resistance against MYMV disease through insect vector resistance.Methods: A field experiment was conducted during rabi 2017-18 and 2018-19 at RARS Lam Guntur in a randomized block design with eight greengram genotypes and replicated thrice under receding soil moisture condition. The experiment was conducted using eight greengram varieties (WGG 42, Pusa Vishal, LGG 607, LGG 630, LGG 601, LGG 610, LGG 460 and LGG 450) obtained from RARS Lam Guntur and the genotype LGG 450 was considered as a susceptible check. The estimation of sugars, phenols, tannins, trichome density and SCMR was done at vegetative and reproductive stages of crop growth.Result: A significant variation was observed among the varieties for all the traits observed at vegetative and reproductive growth stages during both rabi 2017-18 and 2018-19. The total sugar content of the greengram varieties varied from 25.55 to 47.32 mgg-1 FW; the leaf phenolic content values ranged from 12.09 to 26.83 mg g-1 FW and the tannins content of the dried leaf samples ranged from 0.020 to 0.055 mgg-1 DW. The Trichome density of the greengram varieties varied from 75 to 162/cm2 of leaf area and the SCMR values ranged from 35.12 to 58.67. Higher seed yield was recorded in the variety LGG 630 followed by WGG 42 and the lower seed yield was recorded in the variety LGG 450 during rabi 2017-18 and 2018-19. The MYMV resistant varieties showed relatively higher phenolic, tannins content and trichome density and lower total sugar content in the leaf. The total sugar content showed a significant negative correlation with the seed yield. The SCMR value was significantly lower in the susceptible varieties of greengram with higher disease scores.