Correlation and path coefficient analysis for grain yield and its attributing traits of maize inbred lines (Zea mays L.) under heat stress condition

Heat stress during the flowering,pollination and grain filling periods affect maize grain yield and itsattributing  traits. Twenty maize inbredlines were evaluated in alpha lattice design with two replications under heat conditionduring spring season from February to June, 2016 at Rampur, Chitwan, Nepal. Meterological data showed maximum mean temperature (46.2–43.28ºC) and minimum(30.52-30.77ºC) in with relative humidity 37.05 to 49.45% inside thetunnel during in April-May which coincided with the flowering, pollination andgrain filling periods. The data wereanalyzed statistically to study the correlation and path coefficient. Theanalysis of variance showed that all the lines were significantlydifferent from each other for all traits anthesis silking interval, SPAD chlorophyll and leaf senescence, tassel blast, leaffiring, plant and ear height, leaf area index, ear per plant, cob length anddiameter, number of kernel ear-1, number ofkernel row-1, number of kernel row, silk receptivity, shelling percentage, thousandkernel weight and grain yield. Grain yield had positive and significantphenotypic correlation with silk receptivity, shelling percentage, cob lengthand diameter, number of kernel ear-1, numberof kernel row-1, number of kernel row, SPAD chlorophyll, thousandkernel weight and significant and negative correlation with tassel blast,anthesis silking interval, leaf area index, leaf firing. Path analysis revealedthat of thousand kernel weight, shelling percentage, number of kernel ear-1and silk receptivity exerted maximum positive direct effect on grain yield.Therefore, selection of genotypes having maximum thousand kernel weight,shellingpercentage, silk receptivity and number of kernel ear-1 andshorter anthesis silking interval, no leaf firing and tassel blast ispre-requisite for attaining improvement in grain yield under heat stresscondition.