Researches on the influence of the sowing period of simple hybrids on seed production for the Turda 200 maize hybrid.

INTRODUCTION The production of certified seed for maize double hybrids is based on the crossing of two simple maize hybrids, one of which is used as a seed producer (maternal form, AxB) and another as pollinator (paternal form, CxD). The production of the seed in the case of double hybrids presents some advantages because the production obtained in the hybridization lot is high, the cost of lower seed production and includes a minimum risk (Penčić and Hadžistević, 1982). Seed quality indices are generally better than by simple hybrids, especially when adverse conditions occur during production (Sarca, 2004). In the production of corn seed, the relationship between the maternal and paternal form is determined by the amount of the pollen of the paternal form, the habitus of the two partners, the sowing mode of the two cross-breeders (concomitant or offset). The possibilities of seed ratio provided by the existing seeds on the agricultural holding and the mode of harvesting each parental form (Haș, 2006). The main features of seed production at the Turda 200 hybrid recommended by ARDS Turda in 2001 year were: – The reaction to androsterility of the maternform: androsterile; – The mother/ father sowing ratio recommended by SCA Turda (2001) was 6: 2 or 12: 4, the recommended density was 50.000-60.000 plants per hectare for the parental form and 60.000-70.000 plants per hectare for the father form; – The sowing mode of the two parental forms was concomitant; – Special works: control of androsterility; – The amount of useful heats needed for maturity of the maternal form of 1.090 ° C Haş et al. (1982) have found that under certain warmer summer conditions there may be a gap in favor of blooming father form up to -8 days. In this situation, it is appropriate to make the offset sowing of the two parental forms, in the first epoch, to resemble the matern form, and the sowing of the pollination form to be done at the rising of the maternal form. Our study aims to verifying the sowing ratio between simple parental hybrids at HD Turda 200, and indentifying the influence of concomitant/ offset sowing of simple parental hybrids on seed production F1 and its characters.