Associations between charcoal rot disease and grain yield in different sowing dates in spring maize (Zea mays L.)

Five maize hybrids of different maturity groups (PMH 10, PMH 8, PMH 7, PMH 2 and DKC 9108) were evaluated against charcoal rot (Macrophomina phaseolina) on five different sowing dates viz. 20th January (D1), 1st February (D2), 15th February (D3), 1st March (D4) and 15th March (D5) during spring 2018 and 2019. As the sowing delayed from 20th January to 15th March, disease severity increased and grain yield decreased. Maximum mean disease severity (61.32%) was observed in hybrids sown on D5 and minimum (40.91%) in hybrids sown on D1 during spring 2018. Mean grain yield decreased from 74.28 to 51.27 q/ha as sowing delayed from D1 to D5 during spring 2018. Same trend was observed during spring 2019, however severity of charcoal rot was comparatively less leading to more yields in the succeeding year. On comparing the hybrids sown on different dates, PMH 10 showed minimum mean disease severity with maximum grain yield during both the years. The morphological traits viz; plant height and ear height of hybrids also tend to decrease as sowing delayed from mid-January to mid-March. There was negative correlation between severity of charcoal rot and plant height (r = − 0.79) and ear height (r = − 0.81) of maize hybrids. In contrast, days to tasseling (r = 0.79) and silking (r = 0.83) had direct effect on grain yield, however disease severity decreased with increase in days taken for tasseling (r = − 0.80) and silking (r = − 0.80). Exposure of late sown hybrids to high temperature (32.71 °C), low relative humidity (37.29%) and less rainfall (6.6 mm) at tasseling and silking stage predisposed them to charcoal rot. Considering these factors, new breeding strategies could be designed for the management of this genetically diverse soil-borne pathogen, M. phaseolina. © 2022, Indian Phytopathological Society.