HETEROSIS AND COMBINING ABILITY OF SOME GRAIN SORGHUM GENOTYPES UNDER NITROGEN STRESS CONDITIONS

doi:10.12816/ejpb.2019.256683

HETEROSIS AND COMBINING ABILITY OF SOME GRAIN SORGHUM GENOTYPES UNDER NITROGEN STRESS CONDITIONS

Document Type : Original research

10.12816/ejpb.2019.256683

Abstract

Thirty grain sorghum genotypes [twenty F₁ crosses, nine parents and a commercial check hybrid H-306] were assessed under two levels of nitrogen (100 kg. N/fed. as a recommended level and 60 kg. N/fed. as a stress level, one feddan = 4200 m²). These crosses and their parental lines were evaluated in the summer seasons of 2017 and 2018 at Shandaweel Agric. Res. Station. The obtained data showed significant differences between years for all the studied traits. Likewise, highly significant differences between the two levels of fertilizer and among genotypes. As well, the differences among crosses, lines, tester, lines × tester and parents were highly significant for all the studied traits in the two seasons except the lines effects for days to 50% flowering and panicle length in 2017 season. Beside, highly significant differences were obtained for crosses vs. parents for all the studied traits in the two seasons, reflecting the presence of heterosis for all the studied traits. A number of crosses was earlier than their parents and several crosses were heavier in 1000- grain weight than the best parents. Moreover, most of the crosses were taller and higher in grain yield per plant than the best parents under the two levels of nitrogen fertilizer and combined across the two seasons. Additionally, decreasing nitrogen fertilizer from 100 kg N/ fed., to 60 kg N/ fed resulted in a decline in plant height, panicle length, 1000 grain weight and grain yield/plant. Decreasing nitrogen fertilizer from 100 kg N/fed. to 60 kg N/ fed led to increasing the days to 50% flowering. Results indicated that the best crosses were (Ash-33 xRsh-76), (Ash-32 xRsh-38) and (Ash-32 x ICSR-92003) each of them gave the highest grain yield / plant across the two seasons under both nitrogen levels. Also, these crosses significantly out-yielded the check hybrid H-306. The female line Ash-32 and the male line ICSR - 92003 were good combiner for grain yield per plant. Thus, these two lines can be used in sorghum breeding program for improving grain yield. Moreover, some crosses showed positive and highly significant SCA for grain yield per plant and 1000 grain weight under both nitrogen levels.

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