INHERITANCE OF COLD TOLERANCE IN CORN

Abstract

Low temperature during early vegetation one of the imitated factor of corn growing in north area. It is necessary to grow cold tolerant hybrids, which will not reduce the yield in case of cold weather in north part of Ukraine. During breeding cold tolerant hybrids, it is important to know about cold tolerance of parental forms. In the same time it is necessary to know how cold tolerant will be inherent by future hybrids from inbred lines.

For cold tolerance testing breeders use laboratory and field methods. Field method is early corn sowing in soil with low temperature (below 10°C). In this case, it is possible to range cold tolerant genotype. Next step is investigation of cold tolerant inheritance by progeny.

The purpose of research –isdefining the character of inheritance cold tolerance in corn. For this were used 10 inbred (7 cold tolerant and 3 nontolerant) for creating 45 hybrids and afterwards their testing on inheritance issue. Hybrids and their parents forms were sown with soil temperature +6-6,5 °Сin lab of breeding and genetic department of National University of Life and Environmental Sciences of Ukraine in 2011. For inheritance of cold tolerance were checked germination rate. Inheritance calculated with method ofG.M. Beil. andR.E. Atkins.  

Results of study.The feature “cold tolerance” usually inherit with positive overdominance, germination rate in hybrids higher than in parental forms. Positive overdominance registered in 51% of hybrids, positive dominance registered in 27% of hybrids,intermediate inheritance in 16%, negative dominance in 4% and negative overdominance in 2% of hybrids. High percent of positive overdominanceand positive dominanceindicates that feature “cold tolerance” has additive genes influence.

During analysis of hybrids which consist from cold tolerant and nontolerant inbred line found that main part of hybrids had positive overdominance and positive dominance – 61,9% and 33,3% accordingly.  One combination (4,8%) had intermediate inheritance. It is mean, that using of one cold tolerant parent increase cold tolerance of future hybrid.

   In case of crossing two nontolerant inbred lines, all hybrids had positive overdominance of this feature.

Crossing two cold tolerant inbred lines produced hybrids with different character of inheritance. 7 combinations (33,3%) had positive overdominance, 5 combinations (23,8%) hadpositive dominance, 6 combinations (28,6%) had intermediate inheritance. Negative overdominance and negative dominance checked in 2 (9,5%) and 1 (4,8%) accordingly. This indicates thatin combination of two cold tolerant inbred lines present different type of genes interaction. In addition to additive influence, there is epistasis that cause decreasing of germination rate compare to parental forms. 

From tested cold tolerant inbred lines the best donors of this feature are Q 170, UCH 37, Ak 135 та FV 243. All received hybrids that included one of these lines had positive overdominance with hp 1,1-3,3 and field germination in rate – 63,1-82,5%.

Conclusions.

1. Involving in crossing one cold tolerant inbred corn line influent positively on cold tolerance of future hybrid.
2. In case of crossing two cold tolerant inbred lines, it is high probability of receiving cold tolerant hybrid. At the same time possible cold tolerance decreasing due to epistasis effect.
3. In 78% hybrids found positive overdominance and positive dominance of cold tolerance inheritance. This indicates that it is necessary to use cold tolerant inbred lines for breeding high yielding corn hybrids for growing in north Uckraine.

4.      Inbred lines Q 170, UCH 37, Ak 135 and FV 243is recommended to use as donors of cold tolerance in breeding process as they transfer this feature to hybrids in crossing.