Genetics of resistance to charcoal rot in maize (Zea mays L.)

Abstract

Among the prevalent diseases of maize, post flowering stalk rot (PFSR) is a disease of economic significance in majority of the maize growing regions of the world. The disease complex is caused by a number of fungal pathogens, of which Macrophomina phaseolina (Tassi) G. Goid (charcoal rot), Fusarium spp. (fusarial stalk rot), Cephalosporium maydis Samra, Sabet and Hingorani (late wilt) and Cephalosporium acremonium Cda (black bundle) are of significance under Punjab conditions [1]. In the PFSR complex, percent incidence varied from 5 to over 40 percent in various locations [2]. Breeding for disease resistance is must for such a disease complex. The genetics of charcoal rot resistance was worked out under artificial epiphytotic conditions. Forty-five crosses developed through diallel crossing in ten inbred lines of maize (Table 1: five lines resistant and five lines susceptible) and inbred parents were evaluated in a randomized complete block design using three replications and two environments [winter 2001-02 (E1) and spring 2002 (E2)]. At flowering stage, 5 random plants were inoculated using tooth pick method of inoculation [3] in a row to create epiphytotics for charcoal rot. Moisture stress was created immediately after inoculation for 10 days to facilitate early establishment of infection. The infection w~s recorded on 1-9 rating scale as suggested by Payak and Sharma [4]. The Percent Disease Index (POI) was calculated by using the formula suggested by Mc Kinney [5].