Evaluation of new single and three- way maize crosses for resistance to downy mildew disease and grain yield under different environments [electronic resource].

By: Contributor(s): Language: English Summary language: Arabic Description: P. 35-43Other title:
  • تقويم هجن فردية و ثلاثية جديدة من الذرة الشامية لمقاومة مرض البياض الزغبي و محصول الحبوب تحت ظروف بيئية مختلفة [Added title page title]
Uniform titles:
  • Alexandria journal of agricultural research, 2005 v. 50 (2) [electronic resource].
Subject(s): Online resources: In: Alexandria Journal of Agricultural Research 2005.v.50(2)Summary: New white 21 inb1'f!d lines of maize were mated to the two testers, inbred line Sd 63 and promising SC Sk17 at Sakha Agricultural Research. Station during 2002 season. The resulting 42 top crosses and the two checks, SC10 and TWC324 , were evaluated in two trials: the first trial during 2003 season at two locations, Sakha and Mallawi, to estimate silking date, ear position, grain yield, ear length and number of rows! ear. While, the second trial was performed in the disease nursery at Sakha Agricultural Research Station during 2003 and 2004 seasons under artificial infection by downy mildew disease to estimate the resistance for this disease. Combining ability analysis for all studied traits were computed via line x tester procedure, as proposed by Kempthorne (1957). The results of the present study were combined over the two locotions in the first trial and over the two years in the second trial and could be summarized as follows: Mean squares d1Ie to lines, testers and their interaction were highly significant for all studied traits, except for testers and lines x testers interaction for number of rows! ear and resistance to downy mildew disease, and lines x testers interaction for ear position. The estimates of the genetic variance indicated that the additive genetic variance was the more important component in the inheritance of silking date, ear position and resistance to downy mildew disease. While, the non-additive genetic variance played the major contribution in the inheritance of grain yield, ear length and number of rows! ear. Whereas, the additive genetic variance was more interacted with environment than non-additive one for all studied traits, except for grain yield and resistance to downy mildew disease. The parental inbred lines, that revealed the highest and desirable GCA effects, were Sk5170/6 for silking date, Sk5l70/1 for ear position, Sk132/234 for ear length, Sd 1011 for number of rows! ear and resistance to downy mildew disease and Sk8170/4 for grain yield. Promising SC Sk17 as a tester was the best general combiner for all studied traits. The highest and desirable SCA effects were obtained for the top crosses, Gm147 x SC Sk17 for silking date, ear length and grain yield, Sk8170/4 x Sd 63 for number of rows! ear and Gm152 x SC Sk17 for resistance to downy mildew disease. The three- way crosses, Sk8170/7 x SC Sk17 and Sd1031 x SC Sk17 were superior for grain yield (38.12 and 38.81 and/fad. respectively), earliness and resistance to downy mildew disease, compa1'f!d to SC10 and TWC 324 for which the grain yield was 37.15 and 36.46 and/fad d, respectively. While, Sk8170/4 x Sd 63 and Sdl0l1 x Sd 63 single crosses exhibited 100% resistance to downy mildew disease under artificial infection. These results suggest the use of these crosses in maize breeding progranu to obtain high yielding ability and high resistance to downy mildew disease.
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New white 21 inb1'f!d lines of maize were mated to the two testers, inbred line Sd 63 and promising SC Sk17 at Sakha Agricultural Research. Station during 2002 season. The resulting 42 top crosses and the two checks, SC10 and TWC324 , were evaluated in two trials: the first trial during 2003 season at two locations, Sakha and Mallawi, to estimate silking date, ear position, grain yield, ear length and number of rows! ear. While, the second trial was performed in the disease nursery at Sakha Agricultural Research Station during 2003 and 2004 seasons under artificial infection by downy mildew disease to estimate the resistance for this disease. Combining ability analysis for all studied traits were computed via line x tester procedure, as proposed by Kempthorne (1957). The results of the present study were combined over the two locotions in the first trial and over the two years in the second trial and could be summarized as follows: Mean squares d1Ie to lines, testers and their interaction were highly significant for all studied traits, except for testers and lines x testers interaction for number of rows! ear and resistance to downy mildew disease, and lines x testers interaction for ear position. The estimates of the genetic variance indicated that the additive genetic variance was the more important component in the inheritance of silking date, ear position and resistance to downy mildew disease. While, the non-additive genetic variance played the major contribution in the inheritance of grain yield, ear length and number of rows! ear. Whereas, the additive genetic variance was more interacted with environment than non-additive one for all studied traits, except for grain yield and resistance to downy mildew disease. The parental inbred lines, that revealed the highest and desirable GCA effects, were Sk5170/6 for silking date, Sk5l70/1 for ear position, Sk132/234 for ear length, Sd 1011 for number of rows! ear and resistance to downy mildew disease and Sk8170/4 for grain yield. Promising SC Sk17 as a tester was the best general combiner for all studied traits. The highest and desirable SCA effects were obtained for the top crosses, Gm147 x SC Sk17 for silking date, ear length and grain yield, Sk8170/4 x Sd 63 for number of rows! ear and Gm152 x SC Sk17 for resistance to downy mildew disease. The three- way crosses, Sk8170/7 x SC Sk17 and Sd1031 x SC Sk17 were superior for grain yield (38.12 and 38.81 and/fad. respectively), earliness and resistance to downy mildew disease, compa1'f!d to SC10 and TWC 324 for which the grain yield was 37.15 and 36.46 and/fad d, respectively. While, Sk8170/4 x Sd 63 and Sdl0l1 x Sd 63 single crosses exhibited 100% resistance to downy mildew disease under artificial infection. These results suggest the use of these crosses in maize breeding progranu to obtain high yielding ability and high resistance to downy mildew disease.

Summary in Arabic.

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