Manifestation and variability of biometric signs in Line-parental components and maize hybrids using different genetic plasma under irrigation

Abstract

The largest absolute indicators of plant height were the lines of late maturity group (FAO 550), namely: B73, X84, X908, X902.

In the late-ripening group of parental forms was the greatest height of plants (184.2 - 247.1 cm). In the Reid plasma lines (BSSS), on average, an excess of the trait was recorded in comparison with other groups of embryonic plasmas (237.0 - 245.1). It was minimal in lines X902 and X908 and was 230.4 cm and 232.5 cm, respectively.

In the Lancaster plasma group, the maximum was recorded in the line Kr9698 (FAO 420) - 219.7 cm, the minimum - 158.7 cm in the medium-ripe line DK296 (FAO 250). The paratypic variability (Vm) of the trait was low, which indicates a sufficient level of homozygosity and stability of the trait under irrigation.

The height of Iodent plasma plants ranged from 169.2 cm in line X22 (FAO 250) to 208.9 cm in line X221 (FAO 270).

The rate of genotypic variability (Vg) within the Lancaster plasma was significantly higher than the rate of modification variability - 11.9% vs. 0.8%. The same trend was observed in the Iodent plasma group - the index of genotypic variability was 6.4% higher than the modification one. The value of genotypic variability among the parental forms as a whole was 12.9%, which indicates the priority of the influence of genotype on the nature of the manifestation of the studied trait and a sufficient variety of baseline.

Newly created lines (parental components) in plant height had slightly lower values from 169.1 to 216.7 cm. The maximum height of plants was observed in the line HN-52-16 (FAO 400) plasma Iodent - 216.7 cm. The minimum - in the line HN-16-16 (FAO 250) plasma Mixed - 169.1 cm.

The newly created lines were characterized by a low level of paratypic variability of the studied trait - 0.95–1.21%, which indicates a high level of homogeneity and a sufficient level of selection stability of the trait. The value of genotypic variability among the newly created lines (parent components) averaged 8.16%. The rate of genotypic variability (Vg) within the Lancaster plasma lines was almost twice as high as the rate of modification variability (2.71% vs. 1.01%, respectively). A similar trend was observed in the parental plasma components Iodent and Mixed, where the coefficient of genotypic variability was significantly higher than the modification (10.2% vs. 0.93% and 8.73% vs. 1.03%, respectively). This indicates a high level of genotypic diversity among the newly created baselines and a high level of stability of the "plant height", which is due to a sufficient level of homozygosity of the new source material.

The level of the trait "plant height" in F1 hybrids is quite convenient to characterize through the abstract indicators of true (Gist) and hypothetical (Ggip) heterosis, which is expressed as a percentage. The Gist indicator shows the ratio of the value of the trait in the F1 hybrid to the parent form with a larger value. The Ggip index, in turn, is calculated by the ratio of the value of the trait studied in the F1 hybrid to its average value in the parental forms.

In our experiments, the highest indicators of true and hypothetical heterosis on the basis of "plant height" were characterized by the following hybrid combinations: DC 445 x HN-19-16 (Gist = 140.8%, Ggip = 144.5%), DC 205710 x HN-15 -16 (Gist = 141.9%, Ggip = 143.6%), HN-7-16 x HN-5-16 (Gist = 127.9%, Ggip = 148.7%), belonging to maturity groups FAO 300–400. These hybrids most fully manifested the effects of overgrowth of tallness.

The manifestation and variability of traits "plant height" and "height of cob attachment" in the lines - parent components and hybrids of corn with the use of different genetic plasmas. The level of heterosis in newly created test crosses under irrigation conditions was determined. The dependences of biometric parameters and their correlation with grain yield in the test of hybrids obtained with the participation of newly created initial forms of different embryonic plasmas were established.

The index of genotypic variability (Vg) was higher than the index of modification variability, which indicates a high level of genotypic diversity among the parental components and a high level of stability of the indicator "plant height". The stability of the manifestation of the feature indicates a sufficient level of achievement of homozygosity of the new source material.

The research was conducted during 2015–2019 in the research field of the NAAS, according to generally accepted methods of field research and guidelines. The following methods were used: general scientific, special, comparative-analytical, regression, information-logical analysis and mathematical modeling.

The ratio of hybrid plant height by maturity groups and yield level showed that for the middle-early group, in the phase of cessation of linear growth, the plant height is 235–265 cm, the grain yield is 12.98–13.81 t/ha; for the middle-ripe group - 255–257 cm with a grain yield of 15.17–15.82 t/ha. For medium-late hybrids, the optimal plant height to ensure high grain yield (more than 15 t/ha) is in the range from 270 to 280 cm. A low stable positive correlation between plant height and grain yield of maize hybrids (r = 0.361), increasing the height of plants with increasing duration of the growing season. There is no straight relationship between yield and the index of the ratio of the height of the attachment of the ear to the height of the plant. The maximum grain yield of the created maize hybrids was observed at the index of the ratio of the height of attachment of the cob to the height of the plant from 0.400 to 0.450. The ratio of the height of attachment of the cob to the height of the plant is a genetically determined trait, well identifies samples of corn and can be used to compile a description and characteristics of the new material.