Effect of Temperature and Humidity on Seed Setting in Maize ( Zea mays L.)

摘要

Maize is a highly cross pollinated crop and used as a test crop in genetic improvement of crop species. Heterosis and hybrid vigour was commercially exploited first time in maize. A large number of hybrids, synthetic and composite varieties of maize have been developed using heterosis breeding. A pre-requisite of hybridization programme in maize is to know the effect of day-to-day weather conditions on cross pollination and seed setting. Keeping this important aspect in mind, a pilot experiment was undertaken to study the effect of temperature and relative humidity on seed setting in maize during hybridization/sib-mating in summer season.Three different populations, namely, ZM-421 (QPM line from CIMMYT), BVM-2 (an extra early maturing composite) andwhite local bulk (WLB, local collection from farmer's field of Jharkhand),were staggered sown on 30-03-2003 and 10-04-2003 in research farm of BAU, Ranchi under irrigated conditions. The silking was started after 38,45 and 50 days of sowing in WLB, BVM-2 and ZM-42, respectively.Bagging was done in healthy and disease free plants in all populations. Hand pollination was started on 22-05-2003 in WLB population (for sib-mating) and continued up to 20-06-2003 for different crosses and ZM-421. Observationson daily mean temperature and relative humidity (maximum and minimum) was recorded for that period. Hand pollinated ears (sibbed and crossed) were tagged, bagged and harvested separately after maturity. Number of seed set per ear were counted. Average seed set was calculated sib/cross wise(.i.e. sib-1 = WLB # (40 plants), cross 1 = WLB x BVM-2 (43 plants), cross 2 = WLB x ZM-421 (24 plants), cross 3 = BVM 2 x WLB (15 plants), cross 4 = BVM-2 x ZM-421 (25 plants), cross 5 = ZM - 421 x WLB (15 plants), cross-6 = ZM 421 x BVM-2 (22 plants) and sib 2 = ZM 421 # (20 plants). Further, data were pooled date wise and average seed set was calculated. Data on number of seed set (pooled) from 22-5-2003 to 20-06-2003 have been presented in Table 1. The maximum temperature ranged between 31.0 deg C and 41.4 deg C on 20.6.2003 and 2.6.2003 respectively, whereas minimum temperature was 21.5 deg C and 28.0 deg C on 7.6. 2003 and 27.5.2003, respectively.