Effect of different proportions of exotic germplasm on grain yield and grain moisture in maize

Abstract

Two main questions in programs introgressing exotic maize germplasm into temperate materials are the choice of available exotic sources to work with, and the proportion of exotic germplasm that should be incorporated into adapted germplasm. The objective of this study was to compare effects of different proportions of tropical maize inbred line NC298 in hybrids male parent on grain yield and grain moisture content, using method of orthogonal polynomials. Methods of direct crosses and backcrosses were used to form four hybrid groups (six hybrids each) containing 0, 25, 50 and 75 percent of tropical exotic germplasm, respectively, by their male parent (or one half of mentioned proportions in the corresponding hybrids). The linear components of the germplasm proportions sum of squares, were significant (p lt 0.01) for both grain yield and moisture content and the cubic effect (p lt 0.05) for grain yield only. Results in this study clearly suggested backcross foundation populations with an adapted line to be appropriate selection sources for both grain yield and grain moisture content.

Inkorporacija egzotične germplazme u genetički materijal umerenog klimata nameće dva osnovna pitanja: izbor i proporciju odgovarajućih egzotičnih izvora. Cilj ovog istraživanja je bio poređenje efekata različitog udela tropske linije kukuruza NC298 u očinskoj komponenti hibrida, na prinos zrna i udeo vode u zrnu, primenom metode ortogonalnih polinoma. Metodom direktnih i povratnih ukrštanja dobijene su četiri grupe hibrida (po šest hibrida u svakoj) koje su sadržale 0, 25, 50 i 75 procenata tropske germplazme, u njihovoj očinskoj komponenti (ili jednu polovinu pomenutih procenata u odgovarajućim hibridima). Sume kvadrata linearne komponente, bile su značajne (p lt 0.01) za prinos zrna i za udeo vode u zrnu, dok su sume kvadrata kubnog efekata bile značajne (p lt 0.05) samo za prinos zrna. Rezultati ovih istraživanja jasno ukazuju da su početne populacije nastale povratnim ukrštanjem sa adaptiranom linijom pogodan izvor za selekciju na prinos zrna i udeo vode u zrnu.