ABSTRACT

Parching (Hurda) sorghum is one of the special varieties of sorghum, which are suitable for making good quality hurda and well fit it into commercial utility. These hurda sorghum varieties are susceptible to several insect pests from the seedling stage to harvest. The experiment was conducted at the RARS, Vijayapura, to study the insect pest reactions in parching sorghum genotypes. Among the genotypes SMJ-1, RSJ-1 demonstrated superior tolerance to shoot fly, stem borer, aphid and shoot bug infestations, resulting in higher grain (2172 kg/ha) and stover yields (2114 q/ha). Conversely, TAKPS-5 was more susceptible to pest damage, leading to lower productivity (1495 kg/ha). Further, morphological and biochemical analyses indicated that genotypes with higher trichome density and lower sugar content in the leaves, were positively correlated with resistance to pests. Whereas DJ6514, lacking trichomes and with higher sugar content was more susceptible.
Among different sowing dates, SMJ-1 sown on I fortnight (FN) of September had highest number of shoot fly eggs (3.80/plant) and dead heart (70.47%). With late sowing in I FN of November the shoot fly incidence was declined by recording lowest number of eggs (0.37/plant) and dead heart (17.44%). On the contrary, aphid and shoot bug infestation was lower in early September sowing, increasing significantly and peaking by early November sowing. Insect pest incidence was negatively correlated with grain and stover yield suggesting yield loss due to insect pest incidence. Assessment of avoidable yield loss due to shoot fly in parching sorghum genotypes under different protection situations recorded minimum avoidable yield loss in SMJ-1(23.63 and 16.00%) while it was maximum in Phule Uttara (33.87 and 17.82%) in cage and RPP plots, respectively. Under RPP, yield loss could be prevented to the extent of 17.72 per cent which was lower than the cage control plot (29.43%).