General and specific combining ability for some physiological characters and yield of maize (zea mays l.) [electronic resource].

Includes references.

Six inbred lines of maize differ in leaf area, dry weight and physiological characters were employed to obtain half diallel of 15 F₁, excluding reciprocal during summer season of 1998, aiming to study gene action and general (GCA) and specific combining ability (SCA) that control some physiological characters in maize. Fifteen F₁ + 6 inbred lines during summer of 1999 were evaluated in Randomized Complete Block Design in three replications in two different environmental conditions, Sakha (Middle Delta) and Sids (Upper Egypt). During summer season of 2000 F₁ ,s + F₂,s (selfed F₁ plant during 1999) + 6 inbred lines were evaluated in RCBD in three replications for leaf area/plant (LA/P), Total dl1' weight/plant (TDW), crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR), specific leave area (SLA) and grain yield (ard/fed) for the genetics of these characters_ and detected the program breeding for improving these characters in maize. The collected data were statistically and genetically analyzed according to Griffing (1956) Model-I, Method-2. The obtained results indicated that the ratio between variance of general to specific combining ability (σ²GCA/(σ²SCA) was more than unity for specific leaf area and relative growth rate in both locations. Meanwhile, values of (σ²GCA/σ²SCA) were less than unity for leaf area/plant, total dry weight, crop growth rate, net assimilation rate and grain yield (ard/fed)in both locations. The inbred lines of maize 2 and 3 showed positive and significant GCA ,effects for leaf area/plant, total dry weight/plant, crop growth rate, relative growth rate and net assimilation rate in both locations. Inbred lines No-1 and No-5 for specific leaf area and No-2 and No-4 for grain yield ard/fed, sbowing that these lines art .good general combining for these characters and can be use in breeding program to improving these traits. Single crosses (2x3,1x5 and 1x6), (2x3, 2x4 and 4x5),(4x5, 1x5, 2x4 and 4x6), (5x6), (1x2, 2x3, 2x4, 2x5, 3x6, 4x5and 4x6) gave positive and significant specific combining ability effects in both locations, giving evidence for (LA/plant), (TDW/plant), (CGR), (NAR) and (grain yield ard/fed) to improve these crosses in breeding program, in the same followed order. These combinations are given valuable information for maize breeder to improve grain yield through physiological characters and this trend one of the greatest interest, nowadays, all over the world to incorporate physiological characters to obtain higher grain yield in maize.

Summary in Arabic.

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