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Drought is one of the most damaging environmental stresses, which decreases the achene yield of sunflower (Helianthus annuus L.). The objectives of our experimentations were to determine the type of gene action in sunflower under drought stress, for the identification of the lines with higher achene yield for purpose of developing hybrid with higher achene yield. Thirty-two single cross hybrids from 12 inbred lines were developed through line × tester mating design through crossing 8 drought tolerant inbred lines with 4 drought susceptible lines. The evaluation experiment was performed under an alpha (0,1) lattice incomplete block design with three replications. The achene yield related traits like DF, DM, PH, NL/P, HD, SG, AY/P and TAW were evaluated under normal irrigation and drought stress conditions. Values of degree of dominance greater than one indicating that traits were under the control of dominant genetic effect. Based on GCA effects, L1 proved good combiner for early flowering, maturity and short stature; while L6 was a good combiner for NL/P, HD and AY/P while L8 for HD, SG, AY/P and TAW under drought stress condition. Based on SCA effects, Hybrid 20 was found a good SCA combiner for early flowering, early maturity, short stature, higher HD, AY/P and TAW under normal as well as drought stress conditions. It was suggested form our study that the lines L1, L6 and L8 can be further used to develop drought tolerant hybrids for higher yield and L5 × L12 (Hy 20) was proposed for general cultivation in irrigated as well as rainfed areas of Pakistan. [ABSTRACT FROM AUTHOR]

An F1 hybrid of Brassica napus L., derived from 5 × 5 diallel, was studied to estimate combining ability, heritability and gene action of morphological and yield associated traits, utilizing randomized complete block design (RCBD) with two replications, at Bacha Khan Agricultural Research Farm (BARF), Charsadda, Khyber Pakhtunkhwa, Pakistan during the growing season of 2017-18. The data were collected for pods related traits and total yield. The results of the study showed significant differences among parents and F1's for all the studied traits. General and specific combining ability analysis revealed non-significant results for the traits under consideration, suggesting the involvement of non-additive type of gene action. A higher broad sense heritability estimate was evident. It was concluded from the combining ability analysis of the present study that genotype 2702 was best general as well as a specific combiner for pod length (PL), seeds pod-1 (SPP), total yield (TY), and 1000 seed weight (SW). In addition, maximum pod length, seeds pod-1, total yield, 1000 seed weight and pods plant-1(PPP) were observed for those F1 hybrids where genotype 2702 was used as seed setter, i.e. 2702 × P1-119 and 2702 × DUNCLED. Higher broad-sense heritability and nonadditive type of genetic variability indicated that it could be integrated as a valuable tool in breeding strategies to choose genotypes of B. napus L. for high yielding traits. [ABSTRACT FROM AUTHOR]

The current trial was conducted in the field area of Plant of Breeding and Genetics, University of Agriculture, Faisalabad, Punjab, Pakistan during 2018-19. Total five female lines (PBG-101,102,103,104 and105) were crossed with three testers (PBG-106,107 and 108) to produce fifteen crosses. The female lines were crossed for production of hybrids in first season. Then these sunflower hybrids with their parents were sown in randomized complete block design (RCBD) using three replications in subsequent season for checking their performance. Then combining ability (GCA and SCA) of different yield contributing and quality related traits was checked. Among the lines (PBG-105) had shown highly considerable negative GCA for plant height, PBG-103 had shown the significant general combining ability (GCA) for head diameter, PBG-104 had shown the highest GCA effect for total achene yield/plant, PBG-104 had maximum oil content. Among the selected testers PBG-106 had highly considerable GCA for head diameter, PBG-108 had the highest GCA effect for oil contents and PBG-107 had maximum GCA for protein contents. Among the crosses PBG-101×PBG-107 had shown the highest negative specific compbining ability (SCA) for plant height (-15.71 cm), PBG-101×PBG-108 had shown the highest SCA for stem girth (0.42 cm), PBG-104×PBG-108 had shown the highest SCA for head diameter (1.29 cm) PBG-103× PBG-107 had shown the highest SCA for oil contents (1.63%) and PBG-104×PBG-108 had shown the highest SCA for protein contents (1.22%). Hybrids showing better results would be used for improvement of local hybrids. [ABSTRACT FROM AUTHOR]

To identify the best parents for using in breeding program to develop drought tolerant genotypes, combining ability analysis was performed for root shoot ratio and relative water contents by using seven genotypes as female and five as male in a line × tester fashion. Thirty five crosses along with twelve parents were grown at the Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad during the year 2017 in randomized complete design in three replications. Data were subjected to analysis of variance and combing ability factor analysis. General combining ability (GCA) and Specific combining ability (SCA) effects were significant for both traits. The parent genotypes 9860, Manthar 2003 and 9610 transmitted high relative water contents and root shoot ratio to its off spring based on positive and significant value of GCA in both moisture environments.. Cross combinations Aas 2011×9610 and Manthar 2003×9495 indicated highest positive significant SCA effects for root shoot ratio and relative water contetns in normal and water deficit conditions. Therefore, these hybrids can be recommended for water deficit tolerant heterosis breeding. [ABSTRACT FROM AUTHOR]

Wheat (Triticum aestivum L.) the most widely grown crop across the globe is considered as the staple food of about 35% population of the world. Being a water-deficit country, Pakistan faces major reduction in wheat production especially in rainfed areas. Photosynthate or current assimilates are among the major carbon sources used during the grain filling period, whereas during moisture stress these may not be available. Hence reserves present in stem and other parts of the plant are important carbon sources for grain filling under stress conditions. Under treatment of Potassium iodide genotype LLR-22 showed the better performance while Nacozari showed the highest grain yield under rainfed conditions. Among crosses, cross LLR 20 x Parula showed the highest value for yield under both environments. Combining ability analysis revealed that under stress conditions, the traits showed different behaviour than the control condition. GL, GW, NGS, PH, DH and SL showed non-additive gene action (GCA< SCA) under control conditions while GW, TGW, YLS and NGS depicted non-additive gene action under treated conditions. GL, PH and DH showed additive type of gene action under treated condition. The crosses Nacozari x LLR 22, LLR 22 x CB 42, CB 42 x LLR 21 and LLR 22 x LLR 20 showed highest SCA effects for traits under study viz. grain yield, grains per spike, plant height and days to heading respectively. LLR 21 can be considered as the best general combiner for multiple agronomic traits under study. [ABSTRACT FROM AUTHOR]

Six maize (Zea mays L.) open pollinated varieties (OPVS) viz; PSEV-3, Azam, Sarhad white, Jalal, Iqbal and Pahari were used in this experiment to determine their combining ability through 6 x 6 diallel mating design. The research was laid out in randomized complete block design with three replications at Cereal Crop Research Institute (CCRI) Pirsabak, Nowshehra (K.P.K) Pakistan during the year 2015. The results displayed highly significant (P≤0.01) variation among above six OPVS for days to germination, plant height, leaf area, number of grains ear-1, grains moisture % at harvest, grain yield and biological yield. Mean square values due to general combining ability were highly significant (P≤0.01) for all the experimental parameters except grain yield and biological yield. Highly significant specific combining ability for direct and reciprocal crosses shows highly significant differences for all the studied parameters. PSEV-3 proved best combiner for days to germination and grains moisture % at harvest while Azam for grain yield and biological yield. Sarhad White was the best combiner for grain yield. Reciprocal effects of Jalal x Iqbal exhibited best combination for leaf area and number of grains ear-1 while Pahari × Sarhad White for grain yield. [ABSTRACT FROM AUTHOR]

Genetic components of wheat were estimated using line × tester mating design in the Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad during the year 2010-11. The study involved six parents i.e. three lines (9021, 9244 and 9247) and three testers (Seher 2006, Miraj-2008 and Lasani-2008). Nine cross-combinations alongwith their six parents were grown under RCBD with three replications in rabi season of 2011-2012. The traits studied were spikelets per spike, grains per spike, grain weight per spike, 1000-grain weight and grain yield per plant. Data were subjected to analyse of variance for these traits. Among genotypes, highly significant differences were recorded for all traits. The line × tester analysis displayed highly significant differences among parents, crosses, parents × crosses interaction, lines, testers and line × tester interactions for almost all the characters studied. Among parents 9021 showed higher mean values for spikelets per spike, grains weight per spike and 1000-grain weight. In case of cross-combinations 9247 × Lasani-2008 had maximum mean values for number of grains per spike and grain weight per spike. Genotype 9247 proved as a good general combiner for spikelets per spike, grains per spike and grain weight per spike while genotype Seher-2006 showed superiority for 1000-grain weight and grain yield per plant. The cross-combination 9021 × Lasani-2008 proved as a good specific combiner for spikelets per spike. These results can be used for future breeding programmes to develop new wheat varieties along with mentioned new traits. [ABSTRACT FROM AUTHOR]

An experiment to study combining ability effects through 6×6 diallel model in maize inbred lines, was laid out in randomized complete block design with three replications at Agricultural Research Institute, Dera Ismail Khan, Pakistan, during 2012. Variance analysis exhibited highly significant (P 0.01) variation among genotypes for days to 50% silking, ear length, kernel rows ear-1, kernels row-1, kernels ear-1 and grain yield. Mean square values due to general combining ability were highly significant (P 0.01) for all studied attributes except kernels ear1 and grain yield. Highly significant variations for specific combining ability of direct and reciprocal effects were observed for all attributes. Azam proved good combiner for days to 50% silking and kernel rows ear-1 while Islamabad Gold for kernels ear1 and grain yield. Islamabad White × Sadaf was the best combiner for grain yield. For reciprocal effects, BS-I × Sahiwal 2002 proved good combiner for kernels row1 and kernels ear-1 while BS-I × Islamabad White for grain yield. Selection in early generation will be more effective in Islamabad White whereas Islamabad Gold in later generation due to dominant and additive genetic background, respectively. [ABSTRACT FROM AUTHOR]

Genetic potential and combining ability were studied in 6 × 6 F1 cross of Gossypium hirsutum L. at the University of Agriculture, Peshawar, Pakistan. Six parental genotypes (CIM-446, CIM-496, CIM-499, CIM-506, CIM-554 and CIM- 707) and their 30 F1 diallel progenies were grown in a randomized complete block design with three replications. Significant (p<0.01) differences were observed among the genotypes for bolls per sympodia, bolls per plant, boll weight, seed cotton yield per plant, lint % and lint index. F1 hybrids showed significant increase over parental means for all the traits. Mean squares due to GCA and SCA were highly significant for all the traits. The GCA mean squares were higher than SCA for majority traits which revealed that additive genes controlled the inheritance. Utilization of best general combiners (CIM-446 and CIM-554) as one of the parents produced promising F1 population (CIM-446 × CIM-554, CIM-446 × CIM-496 and CIM-506 × CIM-554) with desirable SCA and mean performance for yield and fiber traits. Therefore, high × low, low × high and in some cases high × high GCA parents showed best performance for majority traits. Correlation of seed cotton yield was significantly positive with yield related traits however, the association was negative with lint %. Additive gene action controlled the inheritance, and selection in above promising hybrids could be used in early segregating generations and in hybrid cotton production to enhance the seed cotton yield. [ABSTRACT FROM AUTHOR]

Eight promising genotypes were crossed in all possible combinations using 8x8 diallel system for combining ability analysis. Data was recorded for seed yield and some important yield attributes. The results for combining ability analysis indicated significant general combining ability for most of the traits except plant height and siliqua length. UCD-8/4, KJ-119 and BRS-2 were good general combiners for yield related traits. A cross BRS-2 x UCD-8/4 showed best desired SCA for number of primary branches and siliquae per plant. S-9 x Canola Raya for siliqua length, Canola Raya x UCD-8/4 for number of seeds per siliqua, KJ- 119 x BRS-2, BARD-1 x NIFA Raya for 1000-seed weight while cross BRS-2 x UCD-8/4 for seed yield showed good positive SCA, involving at least one of the promising general combiner parents. It was suggested that selection should be delayed up to sixth segregating generation for number of primary branches, number of siliqua per plant, siliqua length and seed yield due to highly significant genotypic mean square and pre-dominant role of non- additive type of gene action while for number of seeds per siliqua and seed weight, selection in early generations would be suitable due to prominance of additive gene action. [ABSTRACT FROM AUTHOR]