Significant Mean Squares Research Articles

Combining ability of yield attributes traits, oil and protein contents in oil seed rape (Brassica napus) under normal and restricted nitrogen application

Combining ability of yield associated traits has been studied quite frequently in oilseed rape (Brassica napus L.) but it was hardly ever studied based on nitrogen levels variations. Six parents along with their 15 F2 half diallel crosses were evaluated in two nitrogen (N) levels including N0 and N+. Analysis of variance revealed significant mean squares of general and specific combining abilities (GCA and SCA) for all the traits studied. The high narrow-sense heritability estimates were found for seed yield and harvest index, implying the more importance of additive genetic effects for and consequently high selection efficiency for improving these traits. Due to low narrow-sense heritability estimates for oil and protein contents and therefore more importance of non-additive genetic effects, selection for improving these traits should be done in later segregating generations. The GCA × N level interaction was significant only for oil content which is indicating of more differences of GCA effect of this trait at two nitrogen levels. Significant N × SCA effect mean squares for harvest index and oil content, revealed significant variation of SCA effects of these traits in nitrogen levels application. Most of the crosses with high seed yield at N0 and N+ had at least one parent with positive GCA effect at both N levels. Among the six parents, PF7045/91 appeared to be the best combiner for seed yield at the N0. This variety also showed high GCA at the N+ but its low oil content at the N+ is certainly disadvantageous as the quality of the hybrid is often intermediate between the two parents.

Sugarcane Genotype Performance in Three Environments (Based on Crop Cycle) at Mardan, Pakistan

Sugarcane breeders often face significant genotype x environment interactions in their trials grown under multiple environments. Hence, genotypes need to be tested for their stability across different environments keeping in view the significant interactions. An experiment comprising 28 sugarcane genotypes (including 2 checks) was planted in two plant and one ratoon crops during 2010 to 2013 in a randomized complete block design with 3 replications. Data were recorded on cane, yield, and quality characters. Analyses of variance showed significant mean squares for crops, genotypes, and their interactions. The linear contrasts of two plant crops were found non-significant for tillering, vigor rate, stalk diameter, Brix, Pol, recovery, and cane yield. However, the contrast for plant crops versus ratoon was non-significant for stalk diameter only. Shukla’s stability variances and yield stability indices (Ysi) showed that no single genotype was stable for all characters. However, genotypes MS-2003-CP-209, MS-2003-CP-275,CoJ-76, MS-2003-CR2-131, and MS-2003-CR5-245 were stable for cane yield. The results of the study indicate the Original Research Article American Journal of Experimental Agriculture, 4(3): 362-375, 2014 363 importance of genotype x environment interaction and stability in the ongoing varietal development program.

Combining Ability Analysis of Some of Grain Yield Stress Indices in Rapeseed (Brassica Napus L.) Varieties

Although most of investigations showed that nitrogen fertilizers gave substantial rapeseed yield increases even in diverse and contradicting conditions but in a few studies were focused on genetic parameters of nitrogen stress effects. Combining ability of some of important grain yield stress indices based on application and non application of nitrogen (N+ and N0) was studied using half diallel of six spring rapeseed varieties and their 15 F2 progenies. Significant mean squares of general and specific combining abilities (GCA and SCA) were observed for potential yield(Yp), Stress yield(Ys), mean productivity (MP), geometric mean productivity (GMP), tolerance index (TOL), stress tolerance index (STI) and stress susceptibility index (SSI), indicating importance of additive and non-additive genetic effects for them. Non significant ratio of GCA to SCA mean square and low narrow-sense heritability estimates were detected for all the indices, indicating the prime importance of non-additive genetic effects. Significant positive GCA effect of Yp, Ys, MP, GMP and STI for PF7045/91 and significant negative GCA effects of them for Option500, indicated the same direction of GCA effects of these indices and GCA effects of Yp and Ys. On compare to SCA effects, most of crosses had significant high parent heterosis for Yp, Ys and and all the stress indices, therefore selection the better combinations based on heterosis will be more effective than SCA effect.

Identification of Potential F<sub>1</sub> Hybrids in Maize Responsive to Water Deficient Condition

The assessment of heterotic F1 combinations is a basic requisite for hybrid seed development. A set of 30 F1 hybrids along with their parental inbred lines were evaluated under both normal and water deficit conditions for various physiological and agronomic traits. Highly significant mean squares due to general combining ability, specific combining ability and reciprocal effect were observed for all traits under both water regimes. Components of variation exhibited greater estimates for GCA variance (б2g) than SCA variance (б2s) for majority of the traits under both normal and stress conditions depicting the predominant role of additive genetic component. Inbred lines NCIL-20-20, D-157 and OH-8 were found to be the best general combiner on the basis of performance regarding grain yield per plant under water deficit condition. The F1 combinations namely, NCIL-20-20 × D-109, NCIL-20-20 × OH-8 and D-157 × NCIL-20-20 were out-performers based on yield and yield attributes under water deficit conditions. On the basis of our results, we recommend these hybrids for further exploitation to assess their potential for commercial cultivation under water deficit condition.

Evaluation of New Yellow Inbred Lines of Maize in Their Testcross for Ear Position and Grain Yield

General and specific combining ability were estimated for different traits in a lines x testers crossing program comprising 36 top crosses produced by crossing eighteen yellow inbred lines with two testers; i.e., inbred line Sk-11 and promising single cross Sk136 (commercial name S.C177, 2013) in 2012 season. The resulting 36 test crosses along with two check hybrids, i.e. SC.168 and TWC353 were evaluated at Sakha and Sids Agric. Res. Stations in 2013 growing season. Significant and highly significant mean squares were found due to locations and hybrids for all traits, also the interaction between locations x hybrids was significant and highly significant for grain yield and ear position, respectively. Mean squares due to lines (L) and testers (T) and their interaction were significant and highly significant for all the studied traits, except testers for grain yield and L x T for ear diameter. The additive gene action was more important than nonadditive gene action for all the studied traits, except ear length and grain yield, while, the non-additive gene action was the most sensitive to environmental conditions than additive gene action for all traits except ear length. The best parental inbred lines which revealed desirable GCA effects were Sk-6054/61 for days to 50% silking and plant height, Sk-6036/58 and Sk-6043/60 for ear position, Sk6061/63 and Sk6061/64 for ear length, Sk-521 for ear diameter and Sk-6035/57 and Sk-6061/63 for grain yield. Whereas, the tester SC Sk-136 was the best combiner for all studied traits except days to 50% silking and plant height. Five crosses, i.e., Sk-5002/47 x SC-Sk-136, Sk-6043/60 x Sk-11, Sk6061/3 x Sk-11, Sk-6061/64 x Sk-11and Sk-521 x Sk136 showed the best specific combining ability effects for grain yield. The best hybrids that showed useful heterosis for both ear position and grain yield were Sk-6035/57 x Sk-11, 6035/57 x SC Sk-136 and Sk-521 x Sc sk136. Two single crosses, i.e.; Sk-6035/57 x Sk-11 (37.03 ard fed -1 ) and Sk6061/63 x Sk-11 (37.25 ard fed -1 ) were significantly superior and outyielded check hybrid SC168 (33.50 ± 2.95) and fourteen three-way crosses were significantly superior and out yielded check hybrid TWC 353 (26.37 ± 2.95 ard. fed -1 ) These single and three crosses

Indian Collections of Turmeric (Curcuma longaL.): Genetic Variability, Inheritance, Character Association and Performance

Twenty seven genotypes of turmeric (Curcuma longa L.) were evaluated to estimate the variability and inheritance pattern, to suggest suitable breeding strategies and to identify productive genotypes. Highly significant mean squares for all the traits indicated large variation among genotypes. High genetic gain through selection is expected for shoot length, leaf area, rhizome yield and dry matter yield because of additive gene inheritance; while curcumin accumulation in rhizome could be improved by selecting the heterotic seedlings as it is governed by non-additive gene. Furthermore, leaf length and curcumin content could be the most effective and reliable selection indices, as indicated by correlation and path coefficients, in identifying the curcumin-rich productive genotypes. A variety of North East India ‘Megha Turmeric-1’ excelled for the traits of commercial importance (dry matter recovery and curcumin yield). Conclusively, the genotypes of North East India were superior to other parts of India for most of the economic traits and potentially useful for genetic enhancement as well as for varietal improvement of turmeric.

Test Cross Mean Performance and Combining Ability Study of Elite Lowland Maize (Zea mays L.) Inbred Lines at Melkassa, Ethiopia

In Ethiopia, there are several maize production constraints, among which shortage of improved varieties is the major one. The objective of this study was to observe the mean performance of crosses and estimate combining abilities for grain yield and other agronomic traits in thirty six maize inbred lines using Line x Tester mating design. Seventy-two lines x test crosses (L1xT1, L1xT2, L2xT1, L2xT2… L36xT1 and L36xT2) and three standard checks were evaluated for 11 traits in alpha lattice design at Melkassa, Ethiopia. Analyses of variances showed significant mean squares due to crosses for all traits. Among the crosses, L34xT2, L36xT2, L30xT1, L19xT1 and L33xT2 crosses were the top five highest grain yield mean performance. While L35xT1, L23xT1, L13xT1, L24xT2 and L15xT1 crosses were lowest mean grain yield performance. GCA Mean squares were significant, but SCA mean squares were non-significant for all traits. The ratio of GCA/SCA mean square was high which exhibited the preponderance of additive gene effects in the inheritance of all traits. Furthermore, the GCA sum of square component was greater than the SCA sum of square for all traits, supported that variation among crosses was mainly due to additive rather than non-additive gene effect. Inbred lines L15, L25, L27, L33, L34 and L35 were the best general combiners for grain yield, and hence were promising parents for hybrids as well as for inclusion in breeding programmes for yield improvements. Inbred lines L2, L3, L4, L6, L10, L27, L30, L31 and L32 had negative and significant GCA effects for the days to anthesis, indicating that the lines had gene combinations that can enhance early maturity.

Combining ability studies for grain yield and other traits in maize (Zea maysL.) over locations

Combining ability analysis for yield and its component traits in maize was performed with 10 parents and the resulting 45 hybrids using diallel cross analysis (excluding reciprocals) in three locations. The results of combining ability analysis revealed significant mean squares due to general and specific combining ability indicating that both additive and non-additive gene actions were important in the inheritance of characters studied. Variances due to specific combining ability (sca) were larger than general combining ability (gca) for all the characters indicating the predominance of non-additive gene action in the expression of various traits. The parents BML-6, BML-7 and BML-5233-5 were good general combiners for yield and majority of the traits over the locations. Hence, these parents can be used in crossing and further exploited for improvement of traits in the population. BML-5233-5 and BML-2 are good general combiners among the parents for earliness i. e. days to 50% tasseling, days to 50% silking and days to maturity. Whereas the hybrids BML-15 × BML-2910, BML-6 × BML-3044, BML-2782 × BML-7, BML-7 × BML-3044 and BML-2486 × BML-3044 were identified as potential ones for yield and yield components based on high sca effects along with high per se performance. These hybrids may be exploited for commercial cultivation by testing them over locations and years for their yield stability.

COMPARATIVE STUDIES OF SOME LONG STAPLE COTTONS AT DIFFERENT LOCATIONS

Comparative studies for thirty eight genotypes descending from twenty one crosses and the two check varieties Giza 90 and Giza 80 were included in Trial A at Seds Agricultural Experimental Station in 2012 season, eighteen genotypes descending from sixteen crosses and the two check varieties Giza 90 and Giza 80 were grown in Trial B at five locations in Middle and Upper Egypt in the same season. The results obtained from Trial A showed that the strains H5118/2011 and H5124/2011 of the cross (G 83 Rad. x Aust.) x G 91, H5128/2011 and H5129/2011 cross [(G 80 x Aust) x G 83], H5150/2011 cross (G 83rad x Kar) x [(G 83 x G 80) x G 89], H6198/2011 cross[[(G 83 x G 80) x G 89] x (G 83 x Delta Pine)]], H7215/2011 cross [(G 83 x G 80) x G 89] x Aust, H8238/2011 cross (Dand. Rad x Karsh), H9244/2011cross [G 90 x Pima S62 (24240)], H9253/2011 cross [G 91 x Pima S62 (24240)], H10268/2011 [G 83 x (G 72 x Dand.) x G 91], H11281/2011[G 83 x (G 72 x Dand.) x G 85] and Breeder1 of the promising cross [G 83 x (G 72 x 5844)] x G 80] recorded significant higher seed cotton yield (SCY) and lint cotton yield (LY) compared with the check varieties Giza 90 and Giza 80. While the crosses [(G 85 x G 83) x G 90], [(G 83 x G 80) x G 89] x Aust, C.B 58 x G 90, H8249/2010 descending from the crosses G 91 x Pima S62 (24202), [G 83 x (G 75 x 5844) x G 91], [(G 83 x G 72) x Dand] x G 85 respectively and breeder2 of the promising cross (Giza90 x Aus) had higher seed and lint cotton yield (SCY and LY) compared with the check varities Giza 90 and Giza 80 in Trial B. The mean squares of the genotypes in Trial A were highly significant for all yield components traits. Combined mean squares results in Trial B of the genotypes (G) were highly significant and significant for all yield traits except for lint index (LI). Environments (E) mean squares were highly significant for all studied yield traits. Genotypes-environments interactions (G x E) mean squares were highly significant for all yield traits except for lint percentage (L%) which showed significant combined mean squares, indicating change in performance of genotypes from one location to another. In other words, the rank of a genotype differed from one location to another. High heritability estimates in broad sense (h.b.s %) were computed for all yield traits in Trial A, indicated that the environment had slightly influence on these traits. Broad sense heritability estimates (h.b.s %) for yield traits in Trial B were low for seed cotton yield (SCY), lint yield (LY) and boll weight (BW), indicated that the environmental factors had effect on these traits. On the other hand, lint percentage (L %), seed index (SI) and lint index (LI) recorded high heritability estimates in broad sense (h.b.s %) (more than 50%), indicating that environment had considerable effect on these traits.. The G.C.V % values ranged from 2.54% for lint index (LI) to 61.65% for lint yield (LY) in Trial A and ranged from 3.98% for lint percentage (L %) to 50.0% for lint yield (LY) in Trial B. These values indicated variable environmental effects on all studied traits.

English

Diallel mating design was used to generate fifteen single cross hybrids including fifteen reciprocals. The hybrids were evaluated together with their parents and thirteen checks at Samaru, Northern Guinea Savannah, of Nigeria in the years 2005 and 2006. The experimental design used was 7 x 7 incomplete lattice designs with three replications. There were significant differences between the various genotypes for all the fifteen traits observed. There was a highly significant difference in replication within year for the traits; days to tasselling, ash contents and ear height while significant differences were observed for the traits; emergence count, plant height, one thousand grain weight and grain yield. The significant mean squares observed for all the agronomic traits indicates that the genetic variability could be utilized for the improvement of yield and other desirable traits in quality protein maize breeding programs. The combined analysis of variance, the source of variation for entries, was partitioned into hybrids vs. parent’s mean squares which were significant for all traits observed except moisture content. This is a preliminary indication of the presence of heterosis in the single cross hybrids. The observed variabilities could be used to develop suitable hybrids and varieties.    Key words: Quality protein maize, variability, hybrids, performance. &nbsp

Hermaphroditism: A Primitive Sex Form for Improving Plant Architecture, Earliness and Yield Traits in Monoecious Ridge Gourd (Luffa acutangula Roxb.)

The present experiment was carried out to evaluate the breeding value of Satputia inbreds and to formulate suitable breeding strategies following 7 × 7 half-diallel mating design for genetic improvement of ridge gourd (Luffa acutangula Roxb.). Twenty-one F1 hybrids along with seven parental lines, including two hermaphrodite inbreds, were evaluated in randomized block design with three replications. The highly significant mean squares due to parents, hybrids and parents versus hybrids for all the eleven traits studied indicate the presence of sufficient amount of genetic variation. Prevalence of additive genetic variance indicates the usefulness of hybridization followed by selection approaches for plant stature and earliness parameters, while heterosis breeding would be suitable to improve yield potential as indicated by predominance of non-additive genetic variance. Plant stature and earliness are peculiar traits of hermaphrodite ridge gourd which is inherited in its progenies. The parents DRG-2, Satputia Long and Satputia Small were good combiners for a number of characters, including yield/plant. Ten crosses having hermaphrodite inbred as one of the parents, excelled for high per se performance along with desirable specific combining ability effects. The present findings reveal the breeding value and potentiality of hermaphrodite Satputia lines in the genetic improvement for “ideal plant type” in ridge gourd.

ESTIMATION OF GENETIC COMPONENTS, HERTABILITY AND CLUSTER ANALYSIS FOR SOME AGRONOMIC CHARACTERS IN RICE.

Nine parents of rice were crossed to obtain 36 F1 hybrids, through half diallel cross. These parents included one exotic variety, four commercial varieties and four promising lines. Hayman's 1954 method was employed for this purpose. The nine parents and their F1s were grown in randomized complete block design with three replications at the Rice Research and Training Center Farm, Sakha, Kafr El-Sheikh, Egypt. Results revealed highly significant mean squares for all characters, suggesting the presence of genetic differences among genotypes for all studied traits. Significant or highly significant and positive of additive component (D) for all characters except for panicle weight and number of panicles plant-1 were found. The dominance components H1 and H2 were highly significant for all characters studied. The environmental component (E) was insignificant for all characters except spikelet fertility% and grain yield plant-1. Heritability estimates in broad sense were high for all studied characters. The nine parents were distinctly classified into five clusters (below 25 Euclidean distance) according to the similarity.

EVALUATION OF SOME EGYPTIAN COTTON GENOTYPES UNDER DIFFERENT ENVIRONMENTS

Thirty-six new cotton strains descending from fourteen Egyptian cotton crosses were included in trial A, and sixteen strains descending from ten crosses were included in trial B in 2009 season using three promising crosses and the commercial variety Giza 86 as checks. All the genotypes belong to Gosssypium barbadense L. Trial A was conducted at Kafr El-Sheikh, whereas trial B was out lined at five locations (Kafr El-Sheikh, El-Dakahleia, El-Monofeia, El-Sharkeia and El-Gharbeia) in Lower Egypt. The results of trial A showed that most of the genotypes belong to crosses significantly surpassed the check variety Giza 86 in both yield and its components. While, trial B showed that the seven strains were superiority across five locations. High heritability estimates in broad sense were recorded for most studied traits in trials A & B indicating that phenotypic selection for these strains could be highly effective. The present study aimed to evaluate some of Egyptian cotton genotypes using stability statistic analysis which were applied to seed cotton yield, lint cotton yield, boll weight and earliness index. The studied traits showed highly significant mean squares for, genotypes, environments and genotype x environment. The genotypes no. 10, 11, 13, 16 and the two promising crosses 10229 x Giza 86 and Giza 89 x Giza 86 observed average level of stability and surpassed mean performance for seed and lint cotton yield. The genotypes no. 10, 12, 13, 15 and the two promising crosses 10229 x Giza 86 and Giza 75 x Sea behaved the same way for boll weight and the genotypes no. 1, 5, 6, 8, 9, 10, 14, 15 and the three promising crosses 10229 x Giza 86, Giza 75 x Sea and Giza 89 x Giza 86 for earliness index. Therefore, these genotypes may be recommended to be released as a commercial stable high yielding cultivar and / or incorporated to be as a breeding stock in any future breeding program aiming for producing stable high yielding lines for seed cotton yields, lint cotton yield, boll weight and earliness index.

English

A study was undertaken to estimate the combining ability in brown sarson through diallel analysis involving ten diverse genotypes. The combining ability analysis revealed significant mean squares for general and specific combining ability for all the traits studied. The estimates of variance due to dominance deviation () were much higher than the corresponding additive genetic variance () for all the traits. The predictability ratio was less than unity for all the traits which indicated that performance on general combining ability of parents alone would not be advisable to select materials in segregating generations, but a combination involving both general and specific combining ability of the parents and particular crosses along with their per seperformance would be more useful in selecting materials in the segregating generations. None of the parents revealed significant and desirable general combining ability effects for all the traits. The study of specific combining ability effects revealed that none of the crosses was a desirable specific combiner for all the traits under study. However, several cross combinations were observed to have highest desirable significant sca effects for these traits. Key words: Combining ability, general combining ability (gca), specific combining ability (sca), brown sarson.

COMBINING ABILITY AND HETEROSIS FOR MAIZE GRAIN YIELD AND SOME AGRONOMIC CHARACTERS

The present study was carried out at the Experimental Station Farm, Faculty of Agriculture, Mansoura University, Dakahlya Governorate, during the two successive seasons of 2011 and 2012 to determine general, specific combining abilities and heterosis for grain yield and yield associated traits by crossing 6 inbred lines of maize in a half diallel mating design. Fifteen F1 single crosses with their parents were planted in a randomized complete block design with three replicates. Results showed that mean squares of crosses were significant for all studied traits i.e. number of days to 50% tasseling and silking, plant height, number of rows/ear, number of grains/row, 100-grain weight, grain yield/plant and shelling percentage. The analysis of variance revealed highly significant mean squares of general combining ability (GCA) and specific combing ability (SCA) for all studied traits, indicating the importance of both additive and non additive genetic effects for these traits. GCA/SCA variances ratios were found to be greater than unity for number of days to 50% tasseling and silking, plant height and 100-grain weight, indicating that the additive and additive×additive types of gene action were greater importance in the inheritance of these 4 traits. Best GCA effects for earliness traits (number of days to 50% tasseling and silking) achieved inbred lines P4 (Inb.173) and P5 (Inb.174), for plant height were P1 (Sd63), P3 (Inb.19), P4 (Inb.173) and P5 (Inb.174), for number of rows/ear were P1 (Sd63), P3 (Inb.19) and P4 (Inb.173), for 100-grain weight was P1 (Sd63). Inbred lines P1 (Sd63) and P2 (Sd7) showed best GCA effects for grain yield. Also P2 (Sd7) and P6 (Inb.170) showed best GCA effects for shelling percentage. Hybrid combinations P2×P5 and P3×P6 showed largest SCA effects for number of days to 50% tasseling, for number of days to 50% silking were P1×P2, P1×P6, P2×P5 and P3×P4, for plant height were P1×P3, P1×P5, P2×P3, P2×P6, P4×P5 and P4×P6, for number of rows/ear were P1×P2, P1×P4, P2×P3, P3×P4, P4×P5 and P5×P6 and for shelling percentage were P1×P3, P1×P4, P2×P3, P2×P4, P3×P4 and P5×P6. Concerning number of grains/row, grain yield/plant and100-grain weight, most of crosses recorded positive significant or highly significant SCA effects. Results showed significant or highly significant heterosis for all studied traits. Cross P3×P6 was the best, with highly significant negative heterosis over mid and better parents for number of days to 50% tasseling. Cross P2×P3 recorded the highest negative heterosis over mid and better parents for number of days to 50% silking. Regarding to plant height, none of the cross combinations showed negative heterosis over mid and better parents. The best cross over mid and better parents for number of grains/row, grain yield and 100-grain weight was P1×P2. Crosses P1×P4 and P5×P6 recorded the highest positive heterosis over mid and better parents for number of rows/ear and shelling percentage, respectively. Therefore, it could be stated that parents with good positive GCA for grain yield (P1 and P2), negative GCA for tasseling, silking date (P4 and P5) and dwarf plant height (P1, P3, P4 and P5) may be extensively used in hybridization program as a donor. The better performing four crosses (P1×P2, P1×P4, P1×P6 and P2×P3) can be utilized for developing high yielding hybrid varieties as well as for exploiting hybrid vigor.

VARIATION, HERITABILITY AND SELECTION RESPONSE OF SEVERAL CHARACTERS IN WHITE YAM (dioscorea rotundata poir)

Phenotypic and genotypic coefficients of variation, heritability, expected genetic gain and selection response were estimated for several agronomic characters among 40 selected clones of white yam. Three hybrid varieties (89-02565, H-2665, 89-2677) were included in the study as checks. Significant mean squares were observed in days to emergence, vine length, spininess, number of vines, and number of tubers, tuber length, tuber girth, tuber yield per hill, fresh tuber yield, and dry tuber yield among the selected 40 clones. Among the selected clones, fresh tuber yield varied from a minimum of 1.5 t/ha to a maximum of 25.5 t/ha. On the contrary, the fresh tuber yield of hybrid checks varied from a minimum of 6.0 t/ha to a maximum of 13.5 t/ha. The magnitude of phenotypic variance and phenotypic coefficient of variation were higher than genetic variance and genotypic coefficient of variation for all characters respectively. High heritability along with high genetic gain and high response to selection were observed for days to emergence, vine length, number of leaves, leaf area, number of vines, number of tubers, tuber per vine, tuber yield per hill, fresh tuber yield, and dry tuber yield. The study revealed that under more suitable environment, single plant selections followed by vegetative propagation should improve selection progress for higher tuber yield.

Stability of seed oil quality traits in high and mid-oleic acid sunflower hybrids

Seed oil content and composition are important considerations in sunflower breeding programmes because these traits are related to oil quality. They are complex traits that are determined by genotypic factors and environmental conditions. The objective of this study was to estimate the interaction between genotype and environment for oil content and major fatty contents in traditional, high and mid-oleic sunflower genotypes and to identify stable genotypes. Combined analyses of variance of oil, oleic and linoleic acid content of 16 genotypes tested over six locations showed highly significant mean squares for genotype, environment and the interaction between them. On average the mid-oleic and standard genotypes had similar oil contents, but the high oleic genotypes had lower oil contents than the standard genotypes. Stability analyses indicated that one standard, one high oleic and one mid-oleic genotype were relatively stable with average to above average oil content. One high oleic genotype was stable across locations with an oleic acid content of above 80 %. The unstable high oleic acid genotypes that showed variation for oleic acid content across locations may be a consequence of location, temperature and rainfall effects. With adequate location and planting dates, high and mid-oleic hybrids could be produced with oil that meets the oil quality standards.

Hermaphrodite inbreds with better combining ability improve antioxidant properties in ridge gourd [Luffa acutangula (Roxb.) L.

An experiment was conducted with the objectives to evaluate the breeding potential of hermaphrodite lines and to suggest suitable breeding approaches following half-diallel mating design for genetic improvement of antioxidant content and activity in ridge gourd [Luffaacutangula (Roxb.) L.] fruits. Twenty-eight genotypes, including seven parental lines and 21 crosses, were grown in randomized block design with three replications for fruit sample collection. The highly significant mean squares due to parents, hybrids and parents versus hybrids; and GCA and SCA for yield and antioxidants (ascorbic acid, total carotenoids, total phenolics, DPPH-RSA, ABTS-RSA and CUPRAC assay) indicate the existence of abundant genetic variation. The per se performance and combining ability of hermaphrodite parents (Satputia Long and Satputia Small) and hybrids of “monoecious × hermaphrodite” cross were found to be superior for antioxidants along with yield potential. The cross combinations with superior per se performance coupled with high SCA estimates and having at least one hermaphrodite parent would be useful for concentrating desirable alleles to improve the antioxidants and yield simultaneously. Thus, hermaphrodite lines in combination with monoecious counterpart have enormous potential to breed “genotypes for higher antioxidants” without compromising yield in ridge gourd.

Combining ability of nitrogen deficiency stress indices for plant height in rapeseed varieties

Although an average plant height is more preferable in most of agronomic crops, less reduction of this trait in stress condition makes yield components and seed yield sustainable in rapeseed varieties. Combining ability, heterosis and heritability of plant height at application and non-application of nitrogen environments (Hp and Hs, respectively) and its related stress tolerance indices were detected in half F2 diallel crosses of six spring rapeseed varieties. Significant mean squares of general and specific combining abilities (GCA and SCA) were detected for Hp, Hs, mean productivity (MP), geometric mean productivity (GMP) and stress tolerance index (STI), indicating the importance of additive and non-additive genetic effects for them. A high narrow-sense heritability estimate was exhibited for STI, emphasizing the prime importance of additive genetic effects for this stress tolerance index. A significant correlation among Hp, Hs, MP, GMP and STI showed the efficiency of these stress indices for improving plant height in plant breeding programme. In comparison to SCA effects, most of the crosses had significant high parent heterosis for Hp, Hs and all the stress indices. RGS003 with a significant positive GCA effect of Hs was considered as a suitable parent for improving this trait and most of the combinations of this genotype had significant negative SCA effects.

Heterosis and Combining Ability in Maize using Diallel Crosses among Seven New Inbred Lines

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.