GENOTYPE X ENVIRONMENT INTERACTION FOR GRAIN YIELD AND ITS COMPONENTS OF SOME YELLOW MAIZE CROSSES

The present study was undertaken to study the gene action, narrow sense heritability, interrelationships among traits and path coefficient analysis for grain yield and its components, silking date, plant and ear height, leaf area index (LAI), specific leaf weight (SLW) and specific leaf area (SLA). Fifteen hybrids produced using a half diallel fashion in 2008 season were evaluated for grain yield and its components and morpho- physiological traits during 2009 season. The obtained results indicate that all estimates of VA and VD were significant for all traits except VA for specific leaf weight and ear length. In addition, VD for grain yield per plot, leaf area index, specific leaf weight, plant height, ear length, ear diameter, number of rows per ear and number of kernel per row. However, the magnitude of VA was consistently larger than that of VD for all traits. High narrow sense heritability estimates were detected for leaf area index (93%), leaf angel (90%), plant height (90%), ear height (89%), ear length (89%), number of rows per ear (89%) and number of kernel per row (83%). However, moderate narrow sense heritability estimates were obtained for grain yield per plot (77%), one hundred kernel weight (77%), silking date (74%), ear diameter (74%), specific leaf area (64%) and specific leaf weight (55%). While it was very low for stay green (5%). These results indicate the importance of choosing the suitable segregating generations for exhibiting the best expression of gene of different studied traits. Correlation coefficients among traits indicated that grain yield was positively and significantly associated with ear diameter (0.788**), one hundred kernel weight (0.747**), ear length (0.600**), specific leaf weight (0.518**), leaf area index (0.466**), number of rows per ear (0.458**), plant height (0.408**), number of kernels per row (0.361*) and silking date (0.351*). The path coefficient analysis was calculated to detect the relative importance of characters contributing to grain yield per plot. Data show that each of ear diameter, one hundred kernel weight and ear length had high positive direct effects on grain yield per plot.

F1 and F2 seeds of four crosses were formed during 2001 and 2002 growing sea-sons. The F2 population’s plants were evaluated during 2003 growing season under the two planting dates (14th May and 29th June) to estimate the phenotypic correla-tion coefficients among eight plants characters and their contributions in the varia-tion of grain yield/ plant at the Agric. Res. Stat. of Fac. of Agric., Ain Shams Univ., Shalakan, Kalubia Governorate, Egypt. Results showed that grain yield/ plant under normal planting date correlated positively and significantly - in most cases - with each of ear diameter, ear length, number of kernels/ row, 100-kernel weight, number of rows/ ear, ear height, plant height and days to silking, while under late planting date, it correlated with each of number of kernels/ row, ear diameter, 100-kernel weight, ear length, number of rows/ ear, ear height and days to silking. Path coeffi-cient analysis estimates indicated that ear diameter; ear length and number of ker-nels/ row can be considered as the most important sources of plant grain yield varia-tion under normal planting date while, under late planting date they were number of kernels/ row, ear diameter, 100-kernel weight and ear length. It was concluded that each of ear diameter, ear length and ear length through its indirect effects via ear di-ameter are considered as the most important sources of plant grain yield variation.

Aim: A study was carried out to evaluate the magnitude of correlation between grain yield and its various contributing characters. Methodology: 39 genotypes of maize, comprising 31 hybrids and 8 parents, were assessed using randomized block design with three replications. The data recorded on twelve quantitative characters including days to 50 percent tasseling, days to 50 percent silking, days to maturity, plant height (cm), ear height (cm), ear length (cm), ear diameter (cm), number of kernel rows per ear, number of kernels per row, 100 kernel weight, shelling percentage and grain yield per plant. Results: The results of this study showed higher genotypic correlation coefficient for all the characters studied compared to the corresponding phenotypic correlation coefficient. This suggests that, despite the strong inherent association between the traits under study, environments’ influence masked its expression. Ear diameter was found to have a strong and significant positive correlation with grain yield per plant at phenotypic (0.9016) and (0.9540) genotypic level followed by ear length (0.8976, 0.9360), number of kernels per row (0.8905, 0.9247), plant height (0.8399, 0.8697), 100 seed weight (0.8070, 0.8544), ear height (0.7170, 0.7550) and number of kernel rows per ear (0.3240, 0.3901). Days to 50% silking and days to 50% tasselling, however, exhibited significant negative association with grain yield, while days to maturity showed non-significant negative. In path coefficient analysis the maximum positive direct effect on grain yield per plant was found by the ear diameter (0.3505), followed by the 100 seed weight (0.2362), ear length (0.2273), number of kernels per row (0.1827), days to 50% silking (0.1269), and shelling percentage (0.1223). Conclusion: The strong correlation of ear diameter, 100 seed weight, ear length and number of kernels per row (0.2971) with grain yield per plant appears to be mostly due to their high direct effects. Therefore, improving yield could be achieved through direct selection for these attributes.

Nine advanced tropical sweet corn (Zea mays L.saccharata) inbred lines were evaluated to determine their performance, to estimate broad-sense heritability of the traits measured and to determine phenotypic correlations among the traits. The inbred lines showed a wide range of performance for husked fresh ear yield and its components. Based on performance and earliness, inbred lines Bakti-1-S7, TSS Melaka-S5, Thailand-S6, MM x Indonesia-S4 and Manis Madu-S7 were found to be superior and could be short-listed for further testing for general and specific combining ability analysis towards development of hybrid varieties. Broad-sense heritability (h2B) estimates obtained from the variance components method were found to be high for number of days to silking (80.5%), plant height (79.9%), number of days to tasseling (66.9%) and ear height (63.7%), moderate for husked ear yield (56.7%), total soluble solid concentration (54.2%), number of kernel rows per ear (53.9%), ear diameter (46.7%), dehusked ear yield (43.1%), number of kernels per row (42.6%) and number of ear per hectare (34.5%), while lowest estimates for dehusked ear length (12.9%) and husked ear length (0.3%). Traits found to be highly correlated with husked ear yield were dehusked ear yield (0.97), number of kernel rows per ear (0.71), plant height (0.69), husked ear length (0.67), ear height (0.66), dehusked ear length (0.63), ear diameter (0.55), number of kernels per row (0.50) and number of ears per hectare (0.49). For selection purposes, it is therefore suggested that emphasis should be given on traits like number of kernel rows per ear, plant and ear height and ear length for yield improvement among the inbred lines.

This study was conducted to analyze the combining ability for yield and some agronomic traits of maize inbred lines at two locations, Tacroof, Kassala Research Station farm and Sawagi in a farmer field, at Kassala state, Sudan Five parental line (TZBRD-ADQ-2, TZBRD-ADQ-3, TZBRD-ADQ-4, TZBRD-AD-5 and TZBRD-COMP-6) and their ten single cross (F1hybrid) (TZBRD-ADQ-2× TZBRD-ADQ-3, TZBRD-ADQ-2× TZBRD-ADQ-4, TZBRD-ADQ-2× TZBRD-AD-5, TZBRD-ADQ-2× TZBRD-COMP-6, TZBRD-ADQ-3× TZBRD-ADQ-4, TZBRD-ADQ-3 ×TZBRD-AD-5, TZBRD-ADQ-3× TZBRD-COMP-6, TZBRD-ADQ-4× TZBRD-AD-5, TZBRD-ADQ-4× TZBRD-COMP-6 and TZBRD-AD-5× TZBRD-COMP-6) of maize developed by using Diallel mating design. Four experiments were conducted in two consecutive summer seasons 2016 and 2017. The studied traits included days to 50% tasseling, days to 50% silking, plant height (cm), ear height (cm), ear length (cm), ear diameter (cm), number of rows per ear, number of kernel per row, 100 kernel weight (g), and grain yield (ton/ha). Out of the five parents considered as the best combiner at Kassala site, such as parent TZBRD-COMP-6, TZBRD-ADQ-3 and TZBRD-ADQ-4, which showed a highly significant general combining ability effects in desirable direction for all studied traits. Therefore, these lines could be utilized in improvement of the respective traits in any breeding programs where hybridization was involved. Regarding to, Sawagi location, the best combiner were the parents TZBRD-ADQ-3, TZBRD-COMP-6, and TZBRD-ADQ-2 recorded highly significant general combining ability effects in desirable direction for 50% tasseling, days to 50% silking, ear length, ear diameter, 100 kernels weight, number of row per ear, number of kernel per row and grain yield. Among the ten cross combinations, the best cross was, TZBRD-ADQ-2× TZBRD-ADQ-3 recorded significant SCA effect in the desirable direction for all traits except days to 50% silking, plant height and number of kernel per row at Kassala location, but at Sawagi location cross TZBRD-ADQ-3×TZBRD-COMP-6 recorded significant SCA effect in the desirable direction for days to 50% tasseling, days to 50% silking, plant height and number of kernel per row, followed by cross TZBRD-ADQ-2×TZBRD-ADQ-3 which recorded a significant SCA effect in the desirable direction for ear height, ear length and grain yield.

Maize is a crop with broad usage globally and is significant in various areas. From an agronomic perspective, it is known for its diversity in both quality traits and adaptation to different conditions. Particularly, there is notable variation in maize genotypes regarding color-related traits and anthocyanin compounds, which have been the focus of recent studies. Commercial maize varieties are widely grown, but efforts to develop new varieties with superior agronomic and nutritional traits are ongoing. Rich in genetic variation, colored maize genotypes are characterized by their high phenolic content and antioxidant activity, which are essential in terms of nutritional and health benefits. This study was conducted to determine the agronomic characteristics of 14 local maize genotypes with varying grain colors and 2 standard varieties under Çanakkale conditions during the main summer cropping seasons of 2021 and 2022, using a randomized block design with three replications. In the study, traits such as days to flowering, plant height, first ear height, ear length, ear diameter, ear weight, kernel weight per ear, and the number of kernels per ear were examined. Significant variation was observed among the local maize genotypes for the traits examined. The days to flowering ranged from 54.9 to 70.0 days, plant height from 114.61 to 230.8 cm, first ear height from 40.8 to 110.8 cm, ear length from 12.9 to 17.7 cm, ear diameter from 29.1 mm to 37.7 mm, ear weight from 59.8 to 109.4 g, kernel weight per ear from 46.3 to 93.7 g, and the number of kernels per ear ranged from 324.5 to 611.4. The local maize genotypes coded as POP3, POP4, POP14, POP5, POP7, and POP9 were found to be promising in terms of kernel weight per ear and plant height traits. These materials are considered potential genetic resources for future breeding programs, especially when evaluated for grain quality and color characteristics.

The present investigation was conducted with nine genotypes in randomized block design during Rabi, 2019-20 at the instructional-cum-research farm, Assam Agricultural University, Jorhat. All the characters exhibited significant genotypic mean squares in analysis of variance except anthesis silking interval, kernel rows per ear and 100 kernel weights. High heritability coupled with high genetic advance was observed for the traits plant height, ear height, ears per plant, ear length, kernels per row, chlorophyll content, leaf area index 60 days after sowing (LAI 60 DAS), LAI 90 DAS, harvest index, grain yield per plant and grain yield per hectare. Significant genetic association of grain yield per plant and grain yield per hectare with days to 50% pollen shed, days to 50% silk, days to 100% dry husk, ear height, kernels per row, LAI 60DAS and LAI 90 DAS. Genotypic path analysis revealed that the characters, days to 50% silk, days to 100% dry husk, plant height, ears per plant, ear diameter and harvest index had the highest positive direct effects on grain yield per hectare while days to 50% pollen shed and ear height had the highest negative direct effect on grain yield per hectare. The hybrids namely, PAC 751, CP 333 and PAC 751 ELITE, were found to be the three best hybrids to possess a high estimate of desirable traits such as days to 50% pollen shed, days to 50% silk, days to 100% dry husk, plant height, ear height, ear diameter, leaf area index at 60 days after sowing, lea area index at 90 days after sowing, grain yield per plant and grain yield per hectare.

Twenty four inbred lines developed by the Ethiopian National Maize Breeding Program were evaluated at Jimma Agricultural Research Center during the main season of the year 2016 in an 8 X 3 Alpha Lattice (0, 1) design with three replications. The objective was to determine the phenotypic and genotypic association among traits in Ethiopian maize inbred lines and to compare the direct and indirect effects of traits on grain yield. Analysis of variance showed statistically significant (p<0.01) differences among the tested maize inbred lines for most of the traits indicating the existence of sufficient genetic variability which can be exploited in future breeding programs. Grain yield per hectare, thousand kernels weight, ear height, ear diameter, anthesis-silking interval, and plant aspect had higher phenotypic and genotypic coefficients of variation. Grain yield showed positive and highly significant (p<0.01) genotypic association with ear diameter, number of kernels per row, days to 50% silking, number of kernel rows per ear, 1000-kernels weight and leaf width. Grain yield also had positive and highly significant (p<0.01) phenotypic correlation with number of kernels per row and ear diameter. Path coefficient analysis revealed that number of kernels per row, number of kernel rows per ear, plant height, days to maturity, 1000-kernels weight, leaf width and plant aspect had a positive direct genotypic effect on grain yield. Number of kernels per row, number of kernel rows per ear, plant height and 1000-kernels weight exerted high direct effects and also indicated positive and strong association with grain yield indicating that they can be used for indirect selection of inbred lines having higher yield potential per se.   Key words: Character association, inbred lines, morphological traits, path coefficient analysis.

Fifteen newly developed yellow maize inbred lines were topcrossed to each of three inbred line testers, i.e.Gz. 658, Sd. 3118 and Sd.3120 at Sids Agricultural Research Station during 2014 growing season.In 2015 season, resulting 45 topcrosses along with three commercial hybrids as check varieties, i.e.SC.162, SC.168 and SC.176, were evaluated in a replicated yield trail conducted at Gemmeiza and Sids.Data were recorded for days to 50% silking, plant and ear height (cm.), ear length (cm), ear diameter (cm) and grain yield adjusted to 15.5 % grain moisture.Combined analysis over the tow locations showed significant differences between the two locations for all studied traits except for grain yield.Mean squares due to crosses, lines and testers were significant for all studied traits.Mean squares due to lines x testers were significant for plant and ear height, ear diameter and grain yield.Mean squares due to lines x locations were significant for all studied traits except for ear diameter.Mean squares due to testers x locations were significant for all studied traits except for ear length.Mean squares due to lines x testers x locations interaction were highly significant for all studied traits except for ear length and ear diameter.The magnitude of δ 2 GCA (average) was larger than that of δ 2 SCA for days to 50% silking, plant height and grain yield.It was recommended that inbred lines 1 , 2 and 4 which possessed the highest GCA effects for grain yield may be considered promising lines for improving grain yield.Also, the crosses ( L7 x Gz. 658), (L8 x Gz. 658) and (L10 x Sd 3118) may be released for commercial cultivation after further testing and evaluation.

A half diallel cross between 7 inbred lines of maize was evaluated under two different nitrogen rates for six quantitative characters. Nitrogen rates, genotypes, parents, hybrids and parents vs crosses mean squares were significant for all traits. Significant genotype x nitrogen rate mean squares were obtained for days to 50% maturity, No. of rows ear-1 and shelling%. Significant interaction mean squares between hybrids x nitrogen rates were detected for days to 50% maturity, No. of rows ear-1 and grain yield plant-1. General and specific combing ability (GCA and SCA) mean squares were significant for all traits. GCA/SCA ratios revealed that the additive and additive x additive types of gene action were the most important expressions for days to 50% maturity, number of rows ear-1 and shelling% in both and nitrogen rates and combined analysis. Significant interaction mean squares between nitrogen rates and GCA and SCA were detected for most traits. The crosses P1xP2 and P1xP7 at the low nitrogen level, P1xP4, P1xP6, P1xP7 and P2xP5 hybrids at the normal nitrogen level and the hybrid P1xP7 in the across nitrogen levels, were out yielded the check hybrid (Pioneer 30K8). Also, single cross P1xP7 did not differ significantly from the hybrid Hytech 2031 in low nitrogen rate and combined analysis for grain yield plant-1. The parental inbred line No. 4 gave a good combiner for No. of rows ear-1 and grain yield plant-1 at both and across nitrogen rate. The most desirable inter and intra allelic interactions were presented by combinations: P1xP6, P1xP7, P2xP6 and P5 xP6 for 100-kernel weight, P1xP2, P1xP4, P1xP6, P1xP7, P2xP3, P2xP5, P2xP7 and P4xP7 for grain yield plant-1 and P1xP4 andP4xP7 for shelling%. These crosses may be prime importance in breeding programs either towards hybrid maize production or synthetic varieties composed of hybrids which involved the good combiners for the traits in view.

Combining ability estimates are important genetic attributes to maize breeders in anticipating improvement via hybridization and selection. To determine the combining ability for yield and yield associated traits, 8 diverse corn inbred lines were used in a half diallel mating design. Twenty eight F1 progenies along with their parents were planted in randomized complete block design with four replications in two locations during two years. Combined analysis of variance showed significant mean squares of general combining ability (GCA) and specific combing ability (SCA) for Days to silking emergence (DS), plant height (PH), 1000-kernel weight (KW), number of kernels in ear row (KR), number of rows in ear( NR ) , ear diameter (ED), cob diameter (CD), kernel yield (KY) indicating that the importance of both additive and non additive genetic effects for these traits. However, high narrow-sense heritability estimates, low degree of dominance and the ratio of estimates of GCA to SCA effects for DS , NR and CD indicated that additive genetic effect was more important for these traits. Most of the crosses with significant SCA effects for KY had at least one parent with significant GCA effects for the same traits. Significant positive correlations were detected between KY and other yield components including KW, KR, NR and ED, therefore these traits can be used as indirect selection criteria for KY improvement. The crosses MO17 × Line8, MO17 × Line 10 and MO17 × Line 12, Line 8 × Line 10 and Line 8 × Line 21 with high values of KY were considered as good cross combinations for improving the trait.

ten advanced yellow maize inbred lines were topcrossed to two inbred lines testers at Giza Agricultural Research Station in 2013. Resulting 20 topcrosses a long with two standarad check hybrids were evaluated for grain yield and some agronomic traits at three locations, i.e., Sakha, Mallawy and Ismaelia Agricultural Research stations during 2014 growing season. Analysis of variance indicated significant mean squares due to crosses for days to 50 % silking, plant and ear heights and grain yield. The Inbred lines; GZ-656, GZ-658, GZ-661 and GZ-662 were high general combiners for grain yield. Among the crosses, four test crosses (GZ-654x078, GZ-656x078, GZ-660x021 and GZ- 661x078) were found to possess positive significant SCA effects mean while better mean performance for grain yield. Negative and significant SCA effects were also observed in two crosses (GZ- 654x021 and CML-121x078) for number of days to 50 % silking.

A half diallel cross between 7 inbred lines of maize was evaluated under two different nitrogen rates for six quantitative characters.Nitrogen rates, genotypes, parents, hybrids and parents vs crosses mean squares were significant for all traits.Significant genotype x nitrogen rate mean squares were obtained for days to 50% maturity, No. of rows ear -1 and shelling%.Significant interaction mean squares between hybrids x nitrogen rates were detected for days to 50% maturity, No. of rows ear -1 and grain yield plant -1 .General and specific combing ability (GCA and SCA) mean squares were significant for all traits.GCA/SCA ratios revealed that the additive and additive x additive types of gene action were the most important expressions for days to 50% maturity, number of rows ear-1 and shelling% in both and nitrogen rates and combined analysis.Significant interaction mean squares between nitrogen rates and GCA and SCA were detected for most traits.The crosses P1xP2 and P1xP7 at the low nitrogen level, P1xP4, P1xP6, P1xP7 and P2xP5 hybrids at the normal nitrogen level and the hybrid P1xP7 in the across nitrogen levels, were out yielded the check hybrid (Pioneer 30K8).Also, single cross P1xP7 did not differ significantly from the hybrid Hytech 2031 in low nitrogen rate and combined analysis for grain yield plant -1 .The parental inbred line No. 4 gave a good combiner for No. of rows ear -1 and grain yield plant -1 at both and across nitrogen rate.The most desirable inter and intra allelic interactions were presented by combinations: P1xP6, P1xP7, P2xP6 and P5 xP6 for 100-kernel weight, P1xP2, P1xP4, P1xP6, P1xP7, P2xP3, P2xP5, P2xP7 and P4xP7 for grain yield plant -1 and P1xP4 and P4xP7 for shelling%.These crosses may be prime importance in breeding programs either towards hybrid maize production or synthetic varieties composed of hybrids which involved the good combiners for the traits in view.

Twenty four white maize inbred lines were top crossed with two testers i.e. SC 162, SC 166 in 2009 growing season. Resulting 48 crosses in addition to two commercial check hybrids i.e. SC 162 and TWC 352 were evaluated at Sakha, Mallawy and Ismaelia Agriculture Research Station Farms during 2010 growing season. Data were estimated on the following traits: silking date, plant height, ear height, grain yield, number of ears /100-plant, ear length and ear diameter. Mean squares for Lines (L), testers (T) and L x T interaction were significantly for all studied traits, except for grain yield and ear length of tester and for ear height and No.of ears/100-plant of L x T interaction. The best GCA effects for grain yield, number of ears/100-plant, ear length and ear diameter were obtained by inbred lines SK5001/1, SK5001/2, SK5001/6 and SK5001/9, respectively. Also, the inbred lines SK5002/12, SK 5002/19 and SK5002/19 showed better GCA effects for silking date, plant height and ear height, respectively. The tester SC162 showed the best GCA effects for grain yield, number of ears/100-plant, ear length and ear height. Moreover, the tester SC166 was the best combiner for earliness, shorter plant type and ear diameter. The best crosses for specific combining ability were SK 5001/6 χ SC162 for earliness, SK5002/20 χ SC162 for plant height, SK5002/22 χ SC166 for grain yield, SK5001/2 χ SC162 for number of ears/100- plant and SK5002/10 χ SC166 for ear length and ear diameter. The highest mean values of crosses for grain yield were obtained from the SK5001/1 x SC162 (33.67 ard. /fed.), SK5001/7 x SC162 (33.59 ard./fed.). These three way crosses outyielding significantly than the commercial hybrids TWC 352 (27.54 ard./fed.) and SC 162 (30.86 ard./fed.). The additive gene effects were more important for silking date, plant height, ear height, grain yield, No.of ears/100-plant and ear diameter. While, the non additive gene effects were important for ear length. Moreover, non additive genetic effects was more interacted by locations than additive gene effects for all studied traits.

Aim: The aim of the present research work was to estimate the genetic variability, broad sense heritability and genetic advance for various yield and its contributing characters of 39 maize genotypes. Methodology: 39 maize genotypes were sown in randomized block design and replicated thrice to evaluate various genetic parameters. The data was recorded on twelve quantitative traits including days to fifty percent tasseling, days to fifty percent silking, days to maturity, plant height, ear height, ear length, ear diameter, number of kernel rows/ear, number of kernels/row, 100kernels weight, shelling % and grain yield/plant. Results: The mean sum of squares due to genotypes for each of the 12 traits under study indicated significant differences in analysis of variance. High to moderate genotypic and phenotypic coefficients of variation as well as genetic advance were observed in the traits yield per plant, plant height, ear height, number of kernels per row, and 100-kernel weight. These findings suggest that the heritability of these traits is most likely the result of additive gene effects and that selection in early generations may be effective for these traits. On the other hand, the remaining characters days to 50% tasseling, days to 50% silking, number of kernel rows per ear, and shelling percentage were recorded with high heritability with low genotypic and phenotypic coefficient of variation and genetic advance suggesting non-additive gene action for control of these traits which provides limited scope for improvement by selection. Conclusion: Among the characters studied, grain yield, plant height, and ear height had high heritability and high values of genetic advance indicating that these characters were controlled by additive gene action and so phenotypic selection is effective for improvement of these traits.