Since we determined stay-green characteristics and characters related to stay-green in inbred lines, to find out the heterosis and heritability of stay-green characters we crossed three inbred lines, Ga209, Hi39 and KS75 in a half diallel and got the three crosses of F1 and F2 selfed from the F1. We planted the three parent lines, and three F1 and F2 generations, and estimated the heterosis, heritability of stay-green characters, days from silking to ear leaf senescence (DELS), fresh leaf number, fresh leaf area and chlorophyll content.

High heterosis was expressed in DELS of the F1 and even of the F2 population in Hi39/KS75. A high positive heterosis of fresh leaf number, fresh leaf area and chlorophyll content was observed in the F1 but a negative heterosis in the F2 populations except for Hi39/KS75. Inbreeding depression in the fresh leaf number, fresh leaf area and chlorophyll content appeared remarkably associated with the progress of growth, especially from 30 to 52 days after silking (DAS) in an April 23 planting, but Hi39/KS75 had low inbreeding depression in DELS compared to the other two F2 populations. Among the characteristics related to stay-green, the fresh leaf number showed the highest heritability. The other characteristics, except the days from silking to maturity, also exhibited relatively high heritability. Hi39/KS75 showed very high heritability irrespective of planting dates. The stay-green score was found to be significantly correlated with the fresh leaf number, fresh leaf area and chlorophyll content at 52 DAS. A multiple regression analysis with the F2 populations revealed that the fresh leaf number was mostly accountable for the variation in DELS and stay-green score, but less accountable at the later growing stage. 

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