The influence of the temperature, sufficient humidity and illumination duration on the (Cg2/+) hybrid expression --Rusanovskaya, EG, Krivov, NV The expression of heterochronous mutations depends on growing conditions. The reaction of the plants carrying the Cg gene to the differences in the light period duration has been first observed by W.R. Singleton (MNL 23, 1949). We evaluated the Cg2 gene expression by the male inflorescence which has had no branches in mutant plants and was only represented by a central axle. Besides, we measured plant height, panicle length, shoot, node and producing ear corn numbers, leaf length and width, and ear corn diameter in the maize hybrid plants.

As we expected, 100% penetration of the Cg2 gene was observed in the Cg2-220 x sr1 bm2, Cg2-220 x lg1 gl2 v4, lg1 gl2 v4 x Cg2-220, and y1 pb4 x Cg2-143-41 combinations grown in both the field and greenhouse. Ordinary branched panicles were only observed in a significant part of the plants in the +o2 gl/Cg2-220 + + hybrid, which did not differ from the common maize phenotypically (Table 1), i.e. growing of hybrid offspring in the greenhouse contributes to the increase in percentage of plants with the heterochronous Cg2 phenotype.

The hybrids grown in the greenhouse had few tillers with shorter and narrower leaves and shortened panicles and reduced plant heights (Graph 1). Graph 1 shows that the cytoplasm of the maternal line changes the distribution pattern of these traits in hybrid plants, i.e. if a marker line is used as a maternal plant, the hybrid offspring are taller and less tillered.

Three major factors, including temperature, efficient water supply and light period duration, influenced the formation of the maize hybrid plants. A four hour illumination in the greenhouse significantly increased the winter daylight. Therefore, the impact of this factor on the reduction of the hybrid plants in the greenhouse was insufficient. A low temperature in the greenhouse making 20 C2 at a sufficient water supply can contribute to the modification of quantitative traits in maize hybrids, which are largely heterozygous for Cg2.

Table 1. The influence of growing conditions on the Cg2 expression combination.
 
  Combination wt Cg2 % wt plant
Field Cg2-220 x o2 gl 131 14 86.2
Greenhouse   6 26 17.8
Field o2 gl x Cg2-220 39 23 62.9
Greenhouse   10 11 47.6

Graph.
 
 


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