Genotypic specificity of soybean [Glycine max (L.) merr.] plastid pigments content under sowing date and interrow spacing

Abstract

Soybean [Glycine max (L.) Merr.] is a legume and the second most planted crop after maize in worldwide. The objective of this study was to evaluate the change in the total plastid pigments content in three soybean varieties depending on the date of sowing and the row spacing was studied during four consecutive years (2018-2021). The Avigea, Isidor and Richi varieties, sown on three dates (I - 28 March - 05 April; II - 19-24 April; III - 09-14 May) at row spacing of 25, 45 and 70 cm were studied in field conditions. The plastid pigments (chlorophyll a, chlorophyll b, carotenoids) was determined in fresh plant samples in the beginning of pod formation stage. The total content of plastid pigments and the chlorophyll a/chlorophyll b and chlorophyll a + chlorophyll b/carotenoids ratios were calculated. The total plastid pigments content varied by years and varieties depending on the date of sowing and row spacing. The date of sowing was found as a factor with stronger effect on the plastid pigments content compared to the row spacing. On average for the period it was found that the total plastid pigments content in the Avigea variety decreased compared to the first date of sowing at all three row spacing, most pronounced at 45 cm. The reduction reached 25.59% on the second date and up to 19.02% on the third sowing date. The strongest effect of the date of sowing on the plastid pigments content was found in the Richi variety on the third date of sowing, where the increase was up to 64.33% at a row spacing of 25 cm and up to 36.02% at a row spacing of 70 cm compared to the first date. The row spacing factor had a smaller effect - for Avigea variety a decrease of 12.31% was reported on the second sowing date and a row spacing of 45 cm compared to the 70 cm accepted row spacing and for Richi variety by 15.79% on the first date and row spacing 45 cm. The chlorophyll a/chlorophyll b ratio decreased at a row spacing of 25 at the second (for Isidor and Richi) and third sowing dates (for Avigea and Isidor).