Good General Combiner For Number Research Articles

Combining Ability Analysis of Yield and Quality Traits in Pumpkin [Cucurbita moschataduch. Ex Poir

The present analysis was carried out with aims to estimate the general and specific combining ability of pumpkin involving six parents namely, Arka Chandan (P1), Ambili (P2), Arka Suryamukhi(P3), Pusa Vishwas (P4), CO 2 (P5) and CO 1 (P6) and 30 F1 hybrids obtained through full diallel analysis in randomized block design with three replication. The observation were recorded for eighteen traits viz., vine length, node number at which first male flower anthesis, node number at which first female flower anthesis, number of primary branches vine-1, days to first male flower anthesis, days to first female flower anthesis, number of male flowers vine-1, number of female flowers vine-1, sex ratio, number of fruits vine-1, fruit weight, polar diameter of fruit, equatorial diameter of fruit, flesh thickness, 100 seed weight, carotene content, total soluble solids and yield vine-1.. The analysis of variance for combining ability among various traits in pumpkin revealed that there were significant differences for all the traits. Among the parents, Ambili was the best general combiner for number of fruits vine-1, yield vine-1 and yield contributing traits. The highest desirable SCA were obtained from a cross of Ambili x Arka Suryamukhi for yield and attributing traits, which was the best and promising hybrid.

Combining Ability Studies on Yield and Yield Related Traits in Tomato (Solanum lycopersicum L.)

Aim: The present study was conducted to generate information regarding the general combining ability (GCA), specific combining ability (SCA), genetic parameters and GCA and SCA variances in tomato.
 Study Design: The parents and F1s were laid out in Randomized block design with 3 replications.
 Place and Duration of Study: The present study was conducted at research farm of Banaras Hindu University, Varanasi. Crosses were generated in Line x Tester design and resultant F1, F2 and parents were evaluated.
 Methodology: After genetic diversity evaluation, ten genotypes were selected and used as females which were crossed with three other selected genotypes used as males in Line × Tester mating design followed by evaluation of their F1 hybrids along with parents.
 Results: The study concluded that Pant T-3 was a good general combiner for plant height, days to 50% flowering and days to first fruit set, Kashi Amrit was a good general combiner for number of primay branches/plant, CO-3 was a good general combiner for number of flower clusters/plant, number of flowers/cluster and number of fruits/plant, H-86 was a good general combiner for number of fruits/cluster, Fla 7171 was a good general combiner for fruit length, fruit width and fruit weight. Based on sca effects best specific combiner for plant height and fruit yield was Punjab Upma × Azad T-5. The ratio of σ2gca/σ2sca is less than unity for all characters except fruit shape index which also indicated the preponderance of non additive genetic variance. High heritability (>60%) combined with high genetic advance (>20%) was observed for fruit yield, number of primary branches/plant, plant height, number of flower clusters/plant, number of flowers/cluster, fruit weight, number of fruits/cluster, number of fruits/plant. These traits can be improved by simple selection in tomato breeding programme.
 Conclusion: From the study it was concluded that best general combiners for various yield and yield related traits were Pant T-3, Kashi Amrit, CO-3, H-86 and Fla 7171. Based on sca best specific combiner for plant height and fruit yield was Punjab Upma × Azad T-5.

Heterosis for yield and its component traits in Indian mustard (Brassica juncea L., Czern & Coss)

Four lines were crossed with eleven testers in line x tester mating design for estimation of combining ability and heterosis for yield and its component characters in mustard (Brassica juncea). Lines PM-25 and PM-27 were foundto be superior general combiners for length of siliqua and seed yield. PM-25 was also found to be a very good general combiner for number of seeds/siliqua and 1000 seed weight. The cross Varuna x Pusa Tarak showed high sca for seed yield followed by Varuna × Pusa LES-39 while for 1000 seed weight trait, Varuna x PM-28 and Varuna x PM-25 were found to be better. Varuna x Pusa Tarak also showed high sca for total number of siliqua/plant.Among the 44 hybrids, Varuna × Pusa LES-39 recorded highest heterosis for seed yield /plant over mid parent and better parent followed by Varuna × PM-27, Varuna × PM-26, Kranti× PM-27 and Varuna × Pusa Tarak. The resultsof this study suggest that the cross Varuna x Pusa Les 39 is best for high seed yield due to high siliqua length, number of siliqua at main axis, total number of siliqua/plant and number of seeds/siliqua.

Estimates of Combining Ability and Association among Morpho-Agronomic Traits of Single Cross Maize (Zea mays L.) Hybrids

Screening genotypes have a crucial role to increase the efficiency of selections in plant breeding program. Therefore, this study was emphasized to determine combining ability and the association between traits among themselves and yield. The experiment was conducted at Haramaya University Research Station (Raare) for two years (2018 and 2019) using 4x7 alpha-lattice design with three replications. Pooled analysis of variance revealed highly significant (p≤0.01) variations among crosses for grain yield and related traits. According to the result of combining ability analysis, parental line L3 was identified as a good general combiner for grain yield, ear diameter, 1000-kernel weight, and days to maturity. Similarly; L1, L2, and L8 proved as the best general combiner for number of kernels per row. Crosses L1×L6, L3×L5, L4×L6, L4×L8, and L5×L7 were found good specific combiners for 1000-kernel weight. Furthermore, the cross L5×L6 was the best specific combiner for ear diameter, whereas L4×L7 for both number of kernels per row and 1000-kernel weight. Likewise, the crosses L1×L5, L3×L8, L6×L7, and L7×L8 were identified as the best specific combiner towards earliness. Moreover, thousand kernel weight showed significant positive correlation with grain yield, conversely, days to anthesis, days to silking, ear aspect, and Puccinia sorghi exhibited significant negative correlation with grain yield at genotypic and phenotypic levels. Ear length, 1000-kernel weight, number of kernel rows per ear, and Turcicum leaf blight had positive direct effect on grain yield at genotypic and phenotypic level. In general, the result presented in the study might be useful for further breeding process to improve the productivity of maize.

Combining Ability of Selected Soybean [Glycine max (L.) Merrill] Parental Lines

Background: The success of hybridization programme depends on the combining ability of parental lines. Methods: Seven soybean genotypes and all their partial diallel crosses in the F2 generation were evaluated in a randomized complete block design at two locations in Nigeria, during the 2017-2018 growing season. Result: Analysis of variance showed that both environments and genotypes were significantly different for all measured traits. The genotype TGx 1988-5F was the best general combiner for earliness in flowering and poding, while TGx 1448-2E was the best general combiner for number of pods/plant and seed yield/plant. Crosses having significant and positive specific combining ability effect for number of pods/plant and seed yield/plant were TGx 1485-1D × TGx 1448-2E and TGx 1988-5F × TGx 1989-19F, respectively. Genotypes TGx 1988-5F and TGx 1448-2E exhibiting good general combining ability for earliness and seed yield/plant, are thus, promising for utilization in the future hybridization programme for soybean improvement.

Combining ability analysis for yield and yield components in bread wheat

Combining ability analysis was studied in a twelve parents of bread wheat (Triticum aestivum L.). Which were crossed in a diallel fashion (without reciprocals) and their 66F1’s were grown in a field experiment at Wheat Research Unit, Dr. P.D.K.V., Akola during in 2017-18 to study the combining ability for grain yield and its component traits. The gca and sca components of variances were significant for all studied characters. The (gca/sca) variances below unity in the generation showed the predominance of non-additive gene actions effects for all the traits. On the basis of general combining ability (gca) effect and per se performance, parents AKAW-5014 and AKAW-4924 emerged as good general combiners for grain yield per plant and average to high combiners for almost all the traits under study. Parent AKW-1071 was good general combiner for number of tiller/ plant and parents AKAW-5014 and AKAW-4924 also exhibited positive gca effects for days to 50% flowering, days to maturity, plant height, number of seed/earhead and grain yield. On the basis of sca effects, the crosses AKW-1071 xHPBW-01, AKAW-5017 x AKAW5014, AKAW-4924 x GW-322 and AKAW-5014 x WB-2 emerged as good specific cross combinations for grain yield per plot. Hybridization scheme for wheat improvement, such as multiple crossing or bi-parental mating could be useful in further manipulation of genes for economic purposes.

Combining ability analysis in sesame (Sesamum indicum L.)

An attempt was made to study the general and specific combining ability in sesame (Sesamum indicum L.) through line x tester analysis by using five lines and ten testers. A total of fifty crosses were developed and eleven quantitative traits were studied. Among the line AT-231 was the best general combiner for days to 50 % flowering, days to maturity, number of capsule per plant, number of seed per capsule, 1000 seed weight, oil content and seed yield per plant and the line RT-54 for days to maturity, width of capsule, 1000 seed weight and seed yield per plant and oil content. Among the tester KMR-69 showed positive gca effects for seed yield per plant and 1000 seed weight. The tester GT-3 was the best general combiner for days to 50 % flowering, oil content, length of capsule and width of capsule. The tester LOCAL was the best general combiner for number of capsule per plant, number of seed per capsule and 1000 seed weight. The tester PRACHI was the best general combiner for number of branches per plant. The cross RT-54 x KMR-69 exhibited significantly high sca effects for the characters viz., number of capsule per plant, width of capsule, 1000 seed weight and seed yield per plant and hence these crosses could be utilized for yield improvement through heterosis and pedigree breeding.

Study of combining ability analysis for seed cotton yield, yield contributing and fibre quality traits in Desi cotton (Gossypium arboreum L.)

The present investigation entitled “Study on heterosis and combining ability for yield, its components and fibre characters in Desi cotton ( Gossypium arboreum L.)” was undertaken to estimate general combining ability effects (GCA) of the parents and specific combining ability effects (SCA) of the crosses. The experimental material comprised of 24 F 1 hybrids obtained by crossing 4 lines with 6 testers in line x tester mating system. Sum total of 36 treatments consisting of 24 crosses, 10 parents and three standard checks were sown in Randomized Complete Block Design. The analysis of variance for combining ability revealed significant general combining ability effects (GCA) and specific combining ability effects (SCA) for all the traits. Among ten parental lines, most of the lines were found to be best general combiner, which had significant general combining ability (GCA)effect for seed cotton yield and its contributing characters including fibre quality traits. Analysis of variance for means revealed significant differences for all the eighteen characters studied. Among females, PA 741 was found to be the best general combiner for 3 characters viz ., days to 50 per cent flowering, days to 50 per cent boll bursting and days to maturity had significant GCA effects. The female PAIG 77 was the best general combiner for three characters viz ., number of bolls per plant, number of seeds per plant and boll weight. The female PA 809 was the best general combiner for 2.5 per cent span length, fibre fineness/micronaire, fibre strength, uniformity ratio and short fibre index. Among males, AKA 2004-29 found to be best general combiner for days to 50 per cent flowering, days to 50 per cent boll bursting, days to maturity and ginning outturn. Male parent ARBAS 1301 was also found to be best general combiner for number of sympodia per plant, number of bolls per plant,number of seeds per boll, seed cotton yield per plant, lint index, seed index, plant height, 2.5 per cent span length, fibre fineness, short fibre index and fibre strength. Male parent GAM 162 found to be best genral combiner for ginning outturn, 2.5 per cent span length and short fibre index whereas, CNA 1016 for boll weight. There was close agreement between per se performance and GCA as well as SCA effects for most of the characters. Observations on various characters indicated that the crosses showing high heterosis and high SCA effects had high per se performance and they involved at least one high combining parent. The combinations PAIG 77 x ARBAS 1301, PA 734 x ARBAS 1301, PA734 x CNA 1016, PA 809 x ARBAS 1301 and PA 741 x JLA 0614 showed significant and desirable SCA effects for most of the yield and fibre quality traits studied, indicating potential for exploiting hybrid vigor in breeding programme.

English

Combining ability estimates were studied for pod shattering and other agronomic traits in eight  parental soybean genotypes of different pod shattering group namely: susceptible to pod shattering, moderately resistant to pod shattering were crossed in a 4 x 4 North Carolina mating design II to generate 16 crosses, due to missing stands encountered in some crosses, 9 successful F1S hybrids were obtained in the present study and evaluated along with the parents to estimate the mode of gene action controlling pod shattering in soybean and the combining ability for pod shattering and other agronomic traits in soybean. The mean square from the analysis of variance for the ten traits measured showed highly significant differences (p<0.01) among the genotypes. This has demonstrated the existence of genetic variability among soybean genotypes with pod shattering under additive gene action. TGX1955-10E, NG/AD/11/08/023 and NG/SA/07/100 were good general combiners for resistance to pod shattering, plant height, days to 50% flowering and days to maturity while NG/MR/11/11/060, NGBOO/08, TGX1740-1F and NG/SA/07/055 are good general combiner for number of seeds/ pod, pod length, hundred seed weight and grain yield. NG/SA/07/100 x TGX1740-1F, NG/MR/11/11/060 x NGBOO129 and NG/MR/11/11/060 x NG/AD/11/08/023 had positive specific combining ability effects for number of branches/ plant, number of pods/plant, pod length, number of seeds/pod, hundred seed weight and grain yield.  NG/MR/11/11/060 X NG/SA/07/055had negative SCA effects for plant height. This implied that these hybrids performed better than the parents GCA effects. This suggests that the cross combination can be advanced for selection in later generation. Key words: Combining ability effects, soybean genotypes, pod shattering, Samaru.

Heterosis F1 Hibrida dan Daya Gabung Galur Mandul Jantan dari Tiga Tipe Sitoplasma dan Galur Pemulih Kesuburan Padi (Oryza sativa L.)

The combining ability provides information on parental lines selection and F1 hybrids having high yield potential. The analysis important to evaluate new parental lines used at hybrid rice breeding. The objectives of the research were to study combining ability of line (CMS/A) and tester (Restorer/R) in producing the new hybrid rice, and to evaluate those new hybrid performance. The research was conducted in November in 2014 to February in 2015 at Indonesian Center for Rice Research field station, in Sukamandi. Mating design and analysis were done using line x tester design. Thirty hybrids and their parental lines were planted in the field using randomized complete block design with three replications. The characters of yield and yield components were observed. Among the lines, CMS IR 58025A was a good general combiner for number of filled grain per panicle, while GMJ 14A was a good general combiner for maturity, and seed set. Among the testers, PK 12 line was the best general combiner for maturity and seed set, while BP 11 was the best general combiner for number of filled grain per panicle. The new hybrid rice with high specific combining ability for grain weight per hill were GMJ 13A/PK 90 (WA), IR 80154A/R 32 (Gambiaca), and GMJ 14A/R 3 (Kalinga). The hybrids rice with the highest standard heterosis compared than Maro and Ciherang, were GMJ 13A/BP 11, GMJ 14A/PK 90, and GMJ 15A/PK 90, each with CMS with genetic background group of WA, Kalinga, and Gambiaca, respectively.

Combining Ability of Yield and Yield Components in Eggplant (Solanum melongena L.) During Summer

Combining ability in eighteen eggplant genotypes were studied at Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur, Bangladesh during March 2007 to September 2009. Eggplant genotypes were evaluated for different quantitative characters. Highly significant variances due to general combining ability (GCA) and specific combining ability (SCA) for all the studied characters indicated the importance of both additive and non-additive gene actions. The predominance of additive gene action was found for most of the studied characters. Considering GCA effects, the parents P 1 , P 2 and P 6 were the good general combiner for number of fruits per plant and yield per plant; P 3 , P 5 and P 8 for fruit weight; P 4 for fruit length and P 3 and P 8 for fruit breadth and P 1 , P 6 , P 2 and P 7 for yield per plant. Considering SCA effects, the crosses P 5 x P 7 were important for fruit length, fruit weight, number of fruits and yield per plant; P 5 x P 8 for fruit breadth, fruit weight, and yield per plant; P 1 x P 6 and P 2 x P 7 for fruit breadth, number of fruit and yield per plant; P 1 x P 6 , P 2 x P 7 , P 4 x P 7 and P 5 x P 7 for number of fruits and yield per plant.

Combining Ability of wheat yield and Some yield Attributes Under Normal and Water Stress Conditions

A half diallel cross among six parents of wheat (Triticum aestivum L.) was achieved for combining ability under recommended irrigation and water stress at Etay EL-Baroud Agricultural Research Station, Agricultural Research Center, Egypt, during 2009/2010 and 2010/2011 seasons in RCBD with three replications. Data were recorded from F1 generation for days to heading, days to physiological maturity, plant height, flag leaf area, spike length, number of spikelets spike-1, number of kernels spike-1, number of spikes plant-1, 1000-kernel weight and grain yield plant-1. Mean squares for genotypes, parents, crosses and parent vs. crosses were significant for all the studied traits in both irrigation treatments. General combining ability (GCA) and specific combining ability (SCA) mean squares were significant for all the studied traits in both irrigation treatments. High GCA/SCA ratios which largely exceeded the unity were detected for all studied traits, except for grain yieldplant-1 under the study in both conditions. Wheat genotype Line 1 (P6) showed the maximum desirable GCA values for days to heading, days to physiological maturity, flag leaf area, spike length, under water stress, number of kernels spike-1and 1000-kernel weight under both conditions. For shortness, the cultivar Sakha 93 (P2) proved to be the best general combiner for plant height under both environments. Meanwhile, Sham 6 under normal conditions and Sahel 1 under water stress conditions were the best combiners for plant height concerning breeding for tallness. The cultivar Gemmeiza 9 proved to be a good general combiner for number of spikelets spike-1 under both conditions. The cultivar Misr 1 found to be the best general combiner for number of spikes plant-1 and grain yield plant-1 under normal condition, while the cultivar Sakha 93 found to be the best general combiner for number of spikes plant-1 and grain yield plant-1 under water stress condition. The cross (Sahel 1 x Sham 6) showed the maximum desirable SCA values for days to heading and days to physiological maturity under both water regime treatments. The cross (Misr 1 x Line 1) exhibited the maximum SCA for plant height under normal conditions, while (Sahel 1 x Gemmeiza 9) showed the maximum SCA for plant height under water stress condition. The cross (Sahel 1 x Misr 1) showed maximum SCA value for flag leaf area under both environments. The cross (Sham 6 x Line 1) was the best specific combiners for spike length under normal conditions, while (Sahel 1 x Sham 6) was the best for spike length under stress conditions. The best specific combiner for kernels spike-1 under both conditions was the cross (Misr 1 x Line 1). The cross (Sakha 93 x Misr 1) showed the best SCA for number of spikes plant-1 under normal conditions while the cross (Sakha 93 x Line 1) was the best one under water stress conditions. For 1000-kernel weight the cross (Gemmeiza 9 x Misr 1) was the best specific combiner under both irrigation conditions. The cross (Sakha 93 x Line 1) exhibited the maximum SCA for grain yield plant-1 under normal conditions while the cross (Sakha 93 x Gemmeiza 9) was the best one under water stress conditions. The crosses (Sakha 93 x Gemmeiza 9), (Sakha 93 x Line 1) and (Misr 1 x Line 1) were prospective in wheat breeding programs since they expressed significant and desirable (ŝij) effects for most traits.

Genetic Mechanism of Morpho-Physiological and Some Agronomic Characters of Ten Bread Wheat Genotypes

Ten bread wheat cultivars from Egypt were crossed in a half diallel design without reciprocals in 2009 /10 season to estimate the genetic effects. Parents and F1`s were evaluated in a randomized complete block design (RCBD) with three replicates in 2010/11 season at Sakha Agric. Res. St. Data were recorded on some morphophysiological and agronomic characters. High significant differences were observed among genotypes for all studied traits. Significant mean squares of combining ability for all characters reflected the role of additive and non-additive effects in the inheritance of the characters. The ratio of general combining ability to specific combining ability (GCA: SCA) indicates that the effect of general combining ability was more prominent for all characters except for grain yield per plant. Among parents, Sids 12 proved the best general combiner for number of days to heading, number of days to maturity, number of kernels per spike, kernel weight and grain yield per plant. Meanwhile, Sakha 94, Gemmeiza 9, Gemmeiza 11 and Misr 2 were the best general combiners for plant height. Moreover, Sids 13, Misr 1 and Misr 2 were the best general combiners for number of spikes per plant. So, these general combiners should be used in breeding programs to enhance most of studied traits. The crosses; Sakha 93 × Sids 12, Gemmeiza 11 × Shandweel 1, Sids 12 × Sids 13, Sids 12 × Misr 1 and Misr 1× Misr 2 included the good combiner parents for improvement of grain yield. The additive genetic component (D) and dominance components (H1 and H2) proved to be significant for most of studied characters. Mean degree of dominance (H1/D) 1/2 indicated over dominance gene effects for all studied characters except for plant height which is controlled by partial dominance gene effects. Moderate to high heritability estimates in narrow sense (h 2 n) were detected for all studied traits except for grain yield per plant which had low estimate.

Estimation of Combining Ability Effects in Mungbean (Vigna radiata L. Wilczek) Crosses 213

An experiment was conducted to estimate the combining ability in mungbean in order to select good general combing parents and desirable crosses. Analysis of variance revealed that the variances due to GCA and SCA were highly significant, indicating importance of additive and non additive gene action in the inheritance of six different characters such as, plant height, number of clusters/ plant, number of pods/ cluster, number of pods/ plant, pod length and test weight. Genotype SML 382 was found to be the best general combiner for all nine characters under study and PUSA 9871 was found to be desirable parent for seven characters viz., plant height, number of primary branches/ plant, number of pods/ cluster, number of pods/ plant, number of seeds/ pod, 100-seed weight and seed yield/ plant. ML 287 and NARP 1-1 were identified as good general combiners for six characters whereas and WGG 37 identified as good general combiner for number of primary branches, number of clusters/ plant, number of pods/ cluster and number of pods/ plant. The crosses SML 382 x WGG 37, PUSA 9871 x WGG 37 and NARP 1 -1 x SML 382 showed significant SCA effects for seed yield/ plant and other yield contributing characters.

BREEDING POTENTIAL OF INDIAN GERMPLASM OF CUCUMIS SATIVUS VAR. HARDWICKII FOR CUCUMBER IMPROVEMENT

The Cucumis sativus var. hardwickii lines had high number of lateral branches per plant (6.44) and number of fruits per plant (18.57) but fruit length (5.03 cm), fruit diameter (3.84 cm) and average fruit weight (53.37 g) were low. Fruit yield per plant ranged from 316.83 g (IC 277048) to 1563.95 g (IC 331620) and its mean value was recorded as 707.22 g. Highly significant and positive phenotypic correlation was found between fruit yield per plant and number of fruits per plant (0.76), average fruit weight (0.73), pulp breadth (0.73), fruit length (0.71) and fruit diameter (0.68). Only one cross PCUC 15 × P 7 showed superiority over better parent (PCUC 15) in negative direction for days to female flower anthesis. Seven crosses exhibited significant heterosis over standard parent in positive direction for no of lateral branches per plant. Three crosses showing significant heterobeltiosis for number of fruits per plant were PCUC 8 × P 7 (44.22%), PCUC 28 x P 5 (18.61%) and PCUC 15 × P 7 (18.44%). Four crosses showed superiority over better parent (cucumber genotypes) for fruit yield per plant. The highest value of heterobeltiosis was estimated in cross PCUC 15 × P 3 (61.61%) followed by PCUC 15 × P 7 (50.90%), PCUC 8 × P 7 (43.01%) and PCUC 15 x P 5 (28.43%). The cucumber genotype PCUC 28 was identified as the best general combiner for earliness, number of fruits per plant, average fruit weight, fruit length and fruit yield per plant. The Cucumis sativus var. hardwickii genotypes P 7 , P 1 and P 3 have been identified as good general combiner for number of fruits per plant and fruit yield per plant. Generation mean analysis showed that additive components were predominant for days to female flower anthesis, vine length and average fruit weight. Interaction effects were predominant for number of lateral branches, number of fruits per plant, fruit length and fruit yield per plant. This study showed that Indian germplasm of Cucumis sativus var. hardwickii has great potential for their utilization for future cucumber improvement program.

GENETIC ANALYSIS AND POWDERY MILDEW RESISTANCE IN BITTER GOURD (MOMORDICA CHARANTIA L.)

The present experiment was conducted at Vegetable Research Farm, Department of Horticulture, Allahabad Agricultural Institute-Deemed University, Allahabad during the years 2003, 2004 and 2005. Ten parents (six lines and four testers) of diverse nature, namely: MC-84 (L 1 ), S-17 (L 2 ), JMC-21 (L 3 ), NDBT-15 (L 4 ), VRBT-94 (L 5 ), Gy-I (L 6 ), VRBT-6-9 (T 1 ), JMC-22 (T 2 ), VRBT-89 (T 3 ), and MC-56 (T 4 ) were selected from 28 lines of bitter gourd for this study. These lines and testers were crossed in a line x tester fashion and 24 hybrids (F 1 ) were made. These hybrids were grown in a randomized block design with three replications. All the genotypes, parents, and hybrids differed significantly for all the traits. In terms of general combining ability, Gy-I (L 6 ) was good general combiner for number of fruits per vine, internodal length, days to first appearance of male flower and vine length. For yield per vine, yield/ha, fruit width, and days to first appearance of female flower, MC-84 (L 1 ) was found to be the best general combiner and S-17 for fruit length. VRBT-6-9 was recorded to be a comparatively better general combiner for powdery mildew resistance. The crosses MC-84×JMC-22 (L 1 ×T 2 ) for yield/ha, MC-84×VRBT-6-9 (L 1 ×T 1 ) for yield per vine, fruit width, days to first appearance of female flower, number of primary branches per vine, and S-17×VRBT-6-9 (L 2 ×T 1 ) for powdery mildew resistance exhibited significant specific combining ability (SCA). Some of the crosses manifest significant parent heterosis for many of the horticultural traits. Vine length and fruit length showed positive significant heterosis, while days to first appearance to female flower manifest negative significant heterosis for several crosses. Two crosses namely, MC-84×VRBT-6-9 and MC-84×JMC 22, were found to have greatest potential in terms of yield/ha, while two other crosses, viz., S-17×VRBT-6-9 and S-17×JMC-22, were found superior in terms of powdery mildew resistance.

STUDIES ON COMBINING ABILITY IN BLACK GRAM (Vigna mungo(L) Hepper)

Combining ability was studied in a 6 x 6 diallel set in blackgram (Vigna mungo (L.) Hepper) for seed yield and its seven components. The g.c.a. effects of the parents showed that T9 was a good general combiner for number of pods per plant and seed yield. The crosses Du 1 x ADT 3 and NPRB 2 x KB 70 gave positive significant s.c.a. effects for number of clusters per plant, number of pods per plant and seed yield per plant. These were identified as promising crosses.

Line x tester analysis for fixed effect model in cotton (Gossypium hirsutum L.)

The data from an experiment in cotton consisting of three testers and 12 lines selected deliberately have been analysed. The investigation showed higher specific combining ability variance for yield of seed cotton and number of bolls, indicating the predominance of non-additive gene action. Of parental lines, H777 was found to possess high g.c.a. effects for seed cotton yield, number of bolls and number of sympodes. Parent H842 contributed only for boll weight, whereas H655 was good general combiner for number of monopodes. There appeared to be better chances for increasing the yield by exploiting hybrid vigour for the number of bolls and boll weight. The presence of marked non-additive gene effects, in addition to additive gene effects, indicated the need for exploiting both the fixable and non-fixable components of genetic variance for increasing productivity in cotton.

STUDIES ON COMBINING ABILITY IN STRAWBERRY (FRAGARIA × ANANASSA): I. NUMBER OF INFLORESCENCES, NUMBER OF FLOWERS, DAYS TO MATURITY AND NUMBER OF FRUITS

A 10 × 10 complete diallel cross was carried out in the strawberry (Fragaria × ananassa Duch.). Significant general (gca) and specific combining ability (sea) effects were recorded. The variances due to general combining ability exceeded the variances due to specific combining ability. Cytoplasmic effects were also noted. The variety Kalimpong Local was found to be a good general combiner for number of inflorescences, number of flowers and number of fruits. The variety Albritton had highest gca effect for number of inflorescences. The variety Premier was a good general combiner for number of flowers. The Redcoat showed highest gca effect for days to maturity. The best specific combination for number of inflorescences was Phenomenal × Jeolikote Local in F1 and Premier × Kalimpong Local in F2. For number of fruits Albritton × Kalimpong Local and Premier × Cavalier were the best.