Introduction: Plant breeders are in search of traits for high grain yielding hybrids (GYHs), genotypes or populations in several crop species including maize. So, the research has been designed to examine a variety of SG traits during entire grain filling (GF) and their association to grain yields (GYs) among the fifteen newly bred single cross maize hybrids. Materials and methods: An RCBD trial of three replications was conducted planting seeds of the hybrids on October 3, 2012 at Rampur, Chitwan in the subtropical foot plain of Nepalese Himalaya. The sowing date of the trial was arranged to expose flowering and grain filling to natural winter and to represent the commercial hybrid maize production season in granary belt. Results and discussion: Although previous studies reported that leaves that stay green long have been found positively grain yield attributing; this study have depicted either long, or short stay-green (SG) are high grain yielding. Polynomial regression equations (PREs) obtained between GYs and numbers of green leaves below ear (BtmGrn) on 110, 125 and 140th day during GF of the FHs (fifteen hybrids) had coefficient of determination (r2) less than 18%. Although it is so, there is still two diagnostic association curves for high GYHs 8, 12, 11, 13, 5, 6 and 7 and medium to low GYHs 10, 1, 14, 2, 9, 15, 4 and 3 separately. After the date, high GYHs still displayed association curve between GYs and BtmGrn. In addition; PREs obtained between GYs and numbers of green leaves above ear (TopE0Grn) during entire GF of the FHs had r2 19 to 53%. Although it is so, there is still separate diagnostic association curve for high GYHs 8, 12, 11, 13, 5, 6 and 7; and medium to low GYHs 10, 1, 14, 2, 9, 15, 4 and 3. High GYHs and medium to low GYHs similarly displayed different association curve between GYs and numbers of total green leaves (GrnLves) on 110 to 155th day during entire GF and that had r2 equal to 21 to 53%. Although r2 of the PRE formed between GYs and days for net ear senescence duration (ErSenDur) has been found higher than PREs formed for days for ear senescence completion (ErSenCmp) and net ear senescence duration (ErSenDur); two meaningful separate quadratic curves can form between ErSenIni and GYs of high GYHs and medium to low GYHs. Curve formed between GYs and days for 0% green PP (plant population) (days for 100% PP senescence) of the FHs reflect strong positive correlation and almost straight line regression among fourteen hybrids except the highest GYH 8. Although the hybrid 8 lost SG almost earliest; but, its GY has been found highest. It means that the hybrid had highly photosynthetic leaves to contribute to high GY. But; fourteen high to low GYHs are inside the strong positive correlation pattern except GYH 8. So, number of days required by hybrids for 0% SG PP can be positive marker for selection of high GYHs.