Studies On Mazia Breeding:

Abd Elsattar Ahmad Abd El-sattar

This study investigated the extent of heterosis, combiningability and their interactions with three nitrogen fertilizer levels (asthree different environmental conditions) for some agronomic characters.Path coefficient analysis for grain yield, regression analysis, and thepredictionof possible double crosses yield were also included. Twosets of diallel crosses were used in this study. The first diallel setinvolved eight inbred lines i,e, Moshtohor 28 (M.28), M.33, M.41, M.44,M.50, M.70c, M.103 and Giza 307-A. The second diallel set involvedseven inbred lines i.e. Moshtohor 50 (M.50), M.54, M.lDl, M.103, M.104,Giza 102 and Giza 307-A, representing wide range of variability inmost of the studied traits. In 1989 growing season, these lines foreach diallel set were sown and were crossed in all possible cross combinationwithout reciprocals to obtain grains of 28 FI straight crosses(first diallel set) and 21 F 1 straight crosses (second diallel set) atthe Agricultural Research and Experiment Center of Faculty of Agriculture,Moshtohor, Kalubia Governorate. In 1990 season, three adjacentexperiments for each diallel set were conducted at the ExperimentalStation of the National Research Center, at Shalakan, Kalubia Governorate.The three experiments were fertilized by 40, 80 and 120 KgN/fed. The first diallel set included 28 FI Ihybrids and D.C. 204 (checkvariety). While, the second set of diallel included 21 FI hybrids andD.C. 204. The experimental design used a randomized complete blockswith three replications In each experiment. Data of the followingtraits were recorded on ten individual plants chosen at random fromeach plot, except silking and tasseling dates where the plot meanbasis was used.Data recorded on :A. Agronomic characters:1. Tasseling date3. Ear height5. Leaf area2. Silking date4. Plant height6. Ear huskB. Yield and yield components:I. Number of ears/plant.3. Ear diameter5. Number of rows/ear7. Grain yield/plant.2. Ear length4. Number of kernels/row6. IDO-kernel of weightAn ordinary analysis of variance was first performed foreach experiment and then a combined analysis was carried out wheneverhomogenity of error variances was realized. Heterosis was computedas the percentage deviation of F I mean performance from check varietyD.C. 204 average value for individual crosses. General and specificcombining ability estimates were obtained by employing Griffing’s(1956) diallel cross analysis designated as method 4 model I. The obtainedresults can be summarized as follows :-I. Nitrogen levels mean squares were highly significant for all studiedtraits except number of ears/plant for both diallel set. Most traitswere significantly increased as the level of nitrogen increased.2. Genotype mean squares were highly significant for all the studiedtraits except number of ears/plant at 40, 80 and 120 Kg N/fed.and combined analysis in the first and second diallel sets, earlength at 110and 120 Kg N/fed. and ear diameter at 110,80 and120 Kg N/fed. and combined analysis in the second diallel set.3. For grain yield/plant, the hybrid (3xll) gave the highest valuefollowed by cross (lIx5) and- then by cross (5x6) in the first diallelset. While, the cross (Jx3), (lIx5) and (lIx5) expressed the highestgrain yield/plant at 110,80 and 120 kg N/fed., respectively.II. The interactions between nitrogen fertilizer levels and hybridsmean squares were significant for all the studied traits exceptnumber of ears/ plant, ear length and number of kernels/ row inthe first diallel set, and for ear height, leaf area, ear husk, 100-kernel weight and grain yield/plant in the second diallel set.5. Heterosis estimates percentages revealed that the first diallelcross, the five crosses; (3xll), (lIx5), (5x6), (7x8) and (Jx2) outyieldedthe D.C. 2011 by 311.11, 26.90, 18.87, 17.117and 13.56 %,respectively over the three nitrogen levels. In the second diallelset, the four F I hybrids (lIx6), (3x6), (2x6) and (2xll) significantlyout-yielded the check variety by 12.16 to 20.79 % with a meanvalue 15.82 % over the three nitrogen fertilizer levels.6. General combining ability mean squares reached the significantlevel of probability for all agronomic traits, yield and yield componentsexcept number of ears/plant in the first diallel set. Whilein the second diallel set, g.c.a. mean squares were significantfor agronomic attributes, number of rows/ear, 1DO-kernel weightand grain yield/plant in the three nitrogen levels as well as atthe combined data, and ear diameter at 120 Kg N/fed. and thecombined analysis.7. Specific combining ability mean squares were significant for allagronomic attributes in two diallel set except plant height at£f0 Kg N/fed. in the second diallel set. In the first diallel set,s.c.a, mean squares were significant for yield and yield componentsexcept number of ears/plant. While, in the second diallel set,s.c.a, variances were significant for 100-kernel weight, grain yield/plant, in the three nitrogen levels and the combined analysis,ear length at 80 Kg N/fed. and the combined data, ear diameterat 120 Kg N/fed., number of rows/ear at 120 Kg N/fed. and thecombined analysis and number of kernels/row at £f0 Kg N/fed.8. High g.c.e.l s.c.e, ratios which largely exceed the unity were obtainedfor all cases except, (ear height at 80 Kg N/fed. in the seconddiallel set), 100-kernel weight at the three nitrogen levels andthe combined analysis, grain yield/plant at £f0 and 80 Kg N/fed.and the combined analysis, and ear length at £f0and 120 Kg N/fed.in the first diallel set, and ear length at 80 Kg N/fed. and numberof kernels/row at £f0 Kg N/fed. in the second diallel set. While,ear length at 80 Kg N/fed. and the combined analysis and grainyield/plant at 120 Kg N/fed. had g.c.a./s.c.a. ratio was equalto unity.9. In both diallel sets, the mean squares of interaction between thethree nitrogen fertilizer levels and both types of combining abilitywere significant for all the studied traits, indicating that themagnitude of g.c.a. and s.c.a. varied from nitrogen fertilizerlevel to another.10. The best combiners were: Parental inbred line Moshtohor 50 forearlines and leaf area, parental inbred line Moshtohor 44 for heightof plant and ear in the first diallel set, parental inbred line Moshtohor28 for earliness and height of plant and ear, parental inbredline Moshtohor 103 for leaf area in second diallel set, and parentalinbred line Moshtohor 103 for yield and most of yield componentsin two diallel set.I J. The three combinations; (3x4), (4x5) and (5x6) in the first diallelset and (4x6), (3x6) and (2x6) in the second diallel set appearedto be the most promising crosses for breeding towards high yieldingpotentiality. Also, the four crosses (2x4), (3x6), (Jx2) and (2x7)would be promising for; earliness, short plant and ear height,leaf area and ear husk in the first diallel set, and, cross (2x6)earliness, short plant and ear height and cross (lx2) for leaf areaand ear husk in the second diallel set.12. Significant positive phenotypic correlation values were obtainedbetween grain yield/plant and number of kernels at 120 Kg N/fed.and 100-kernels weight at 40 and 120 Kg N/fed. in the first diallelset. Also, it were significant between grain yield/plant and eachof its components at 120 Kg N/fed. and each of number of rows/earand 100-kernel weight at 80 Kg N/fed. and 100-kernel weightat 40 Kg N/fed. in the second diallel set.13. Based on multiple linear regression analysis, three characterscould be arranged in their relative contributions in grain yieldas 100-kernel weight, number of rows/ear and number of kernels/row in two diallel set.14. Based on path coefficient· analysis, the most important sourcesof variation in plant yield were: the direct effect of 100-kernelweight, number of rows/ear and number of kernels/row at thethree nitrogen levels in the first and second diallel set.15. Predictions of the yield for the possible 210, 105 double crossesin the first and second diallel set, respectively were estimated.The predictions of double crosses: (lx3) (2x4), (lx3) (4x6), (lx5)(2x4), (lx5) (4x6), (2x4) (3x5), (3x5) (4x6), (3x5) (4x7), (3x5) (4x8),(3x7) (4x8), (4x6) (5x7) and (4x8) (5x7) at 40, 80 and 120 Kg N/fed.as well as at the combined data in the first diallel set, and doublecrosses : (lx4) (2x6), (lx6) (3x4), (Lxs) (2x3), (2x3) (4x6), (2x6)(3x4), (3x4) (6x7) and (3x7) (4x6) in the second diallel set overthe three nitrogen levels would exhibited high performance andout-yielded the check variety D.C. 204. It could be concludedthat these double crosses offer a possibility for increasing grainyield of maize especially at 80 Kg N/fed.