Broad-sense Heritability Estimates Research Articles

Genetic Parameters for Sorghum Varieties in Different Population Densities

Experiments were carried out at Field Crop Dept., College of Agric., Univ. of Baghdad, during spring and fall seasons of 2013. The objectives were to estimate the:1- Phenotypic, genotypic and environmental variations, 2- Genotypic and phenotypic coefficient of variation and 3- broad sense heritability for seven traits days to 50% anthesis (DTA), plant height (PH), leaf area (LA), panicle length (PL), panicle weight (PW), crop growth rate (CGR), and grain yield per plant (GY). These traits and variances were recorded on three genotypes of sorghum (Sorghum bicolor L. Moench), Enqath, Rabih, and Kaffier. Results of statistical analysis showed that most traits had higher genotypic and phenotypic variances than environmental variance estimate, which indicated these traits were genotypic origin, and can be exploited in breeding programs. The genotypes exhibited varying degrees ratios of heritability for most traits. Such traits were responded positively to selection due to high broad sense heritability estimates. These data demonstrated high diversity for the traits studied of genotypes used.

Genetic Variability, Performance and Yield Potentials of Ten Varieties of Cowpea (Vigna unguiculata (L) Walp) under Drought Stress

Food security is being threatening globally as a result of climate change and depletion of natural resources. Cowpea is one of the important crops that is needed to solve the world nutrition problem. Improvement for drought tolerance in cowpea can serve to mitigate the effect of drought stress resulted from climate change. Understanding the magnitude and type of genetic variability help the breeder to determine the selection criteria and breeding methods to be used for improvement purposes under drought stress. Ten cowpea genotypes were evaluated on the field during the dry season for two years in a RCBD (r=3) under well-watered (WW) and water-stressed (WS) environments. Data were collected on both morpho-physiological and agronomic characteristics. There was significant varying degree of reduction across the parental lines evaluated for all the characters. With respect to number of pods per plant, the highest reduction (64.8%) was observed in IT99K-513-21 and the lowest (-211.7%) in IT89KD-288; for number of seeds per pods, the highest (51.4%) in IT99K-513-21, the lowest (-2.7%) in TVU7778; for 100-seed weight, the highest (50.0%) in IT97K-499 and the lowest (-1.3%) in IT93K-432-1 and for total seed weight, the highest (82.8%) in IT92KD-357-3 and the lowest (-20.8%) in Danilla. The phenotypic and genotypic coefficient of variations were larger under WS than WW. Broad sense heritability estimates ranged between 12.3% in number of branches per plant to 99.0% for number of days to 50% ripe pods under WS. This genetic variability to drought stress provides opportunity for cowpea genetic improvement.

Heritability and correlation analysis in Bt and non-Bt cotton (Gossypium hirsutum L.) genotypes

The present research was carried out to analysis the heritability and correlation in 24 Bt and non-Bt cotton genotypes for yield, yield related and fiber traits, including plant height (cm), first sympodial node number, first effective boll node number, sympodial branches plant-1, bolls plant-1, boll weight (g), seed index (g), micronaire value (μg/inch), staple length (mm), ginning outturn percentage and seed cotton yield plant-1 (g). The results exhibited that genotypes differed significantly at P ≤0.01 for all the traits studied. It indicates that the significant genetic diversity among the genotypes for further evaluation. High heritability estimates in broad sense was found for most of the studied traits except 1st effective boll node number, which displayed moderate heritability estimates. High heritability values for majority of the traits suggested that the variation observed was mainly under genetic control and was less affected by environmental factors, referring the influence of additive gene action for most of the studied traits. Hence, the improvement of these traits can be made through direct phenotypic selection. Among the recorded traits, only four traits i.e. 1st effective boll node number, sympodial branches plant-1, bolls plant-1 and ginning outturn percentage developed a significant and positive associations with seed cotton yield plant-1. Thus, selection for these traits will assist in selecting genotypes with greater seed cotton yield plant-1. Keywords: Heritability; Correlation; Genetic Advance; Seed cotton yield; Bt-Cotton http://dx.doi.org/10.19045/bspab.2016.50114

Genetic potential and traits association in desi and kabuli chickpea genotypes

The present experiment was carried out at the experimental area, University of Agriculture, Peshawar, Pakistan during the growing season of 2013-14. The current research work was planned to evaluate the genetic potential and traits association in 20 Desi and Kabuli chickpea genotypes (10 Desi and 10 Kabuli). The genetic materials were grown in a randomized complete block design (RCBD) with three replications. Data were collected on plant height (cm), secondary branches plant -1 , pods plant -1 , seed yield (kg ha -1 ), biological yield plot -1 and harvest index. Genotypes revealed significant differences for most of the traits which ranged from 63.66 to 105.28 cm for plant height, 8 to 18 for secondary branches plant -1 , 43 to 64 for pods plant -1 , 862 to 2481 kg for seed yield (kg ha -1 ), 1383 to 3576 g for biological yield plot -1 and 20 to 39% for harvest index. Mean squares showed highly significant differences (P≤0.05) for comparative performance of Kabuli and Desi genotypes. Mean value for seed yield (kg ha -1 ) of Kabuli genotypes was 1210.10 kg, which was comparatively less than mean value of Desi genotypes which was 1823.90 kg. Among Kabuli genotypes, analysis of variance (P≤0.05) showed significant differences for most of the traits. Genotype NKC-5-S14 showed minimum (861.60 kg ha -1 ) seed yield while maximum (1589.30 kg ha -1 ) seed yield was recorded for NKC-5-S16. Mean squares in Desi genotypes also revealed significant differences (P≤0.05) for most of the traits. Maximum (2481.3 kg ha -1 ) seed yield was given by genotype NIFA-2005, while minimum (1002.90 kg ha -1 ) seed yield was recorded for genotype SL-3-29. Broad sense heritability estimates for yield and yield components were moderate to high that ranged from 54% to 92%. Positively and highly significant association of seed yield was observed with biological yield plot -1 (r = 0.85**) and harvest index (r = 0.42**), while significantly negative correlation was observed with 100-seed weight (r = -0.26*). Biological yield plot -1 , harvest index would be the proper choice criteria for better seed yield in chickpea. Results showed that genotypes NIFA-2005, NDC-4-20-5, SL-3-64, NDC-4-20-4 and NKC5-S16 performed better and could be utilized as a part of future breeding projects for the improvement of high yielding cultivars.

Intraspecific trait variation affecting astaxanthin productivity in two Haematococcus (Chlorophyceae) species

Microalgae are increasingly used as commercial sources of high-value compounds. However, the nature and genetic basis of variation in commercially relevant traits remain understudied. This study focuses on the green alga Haematococcus pluvialis, well-known for accumulating the carotenoid astaxanthin. We examined intra- and interspecific variation and correlations between six traits related to astaxanthin productivity among 30 natural isolates and cultivated strains of two Haematococcus species. Significant intraspecific genotypic variation was found for all traits assessed in both species (broad sense heritability estimates H2=0.48–0.89), resulting in a fifteen-fold variation in astaxanthin productivity between the poorest and the best-performing strain. The two species differed in five of the six traits. Cultivated strains had a lower astaxanthin productivity compared to natural isolates of H. pluvialis, possibly reflecting loss of photoprotective capacity during long-term cultivation. In general, trait correlations were weak yet stronger in H. rubicundus than in H. pluvialis. Most of the variation in overall astaxanthin productivity could be explained by the differences in post-stress traits. Our results reveal extensive trait variation among isolates of a commercially interesting microalga. We recommend natural strain panels as a valuable tool for cost-efficient trait mapping and to select targets for genetic engineering, marker-assisted strain selection or breeding aiming at the optimization of astaxanthin productivity.

Gene action and component of genetic variance analysis in the thermo sensitive genetic male sterile (TGMS) line in rice (Oryza sativa L.)

The field experiment conducted with eighteen TGMS lines, seventy two F1’s and four checks in randomized complete block design with three replications at the Norman E. Borlaug Crop Research Centre of Govind Ballabh Pant University of Agriculture and Technology, Pantnagar during Kharif 2013 and Kharif 2014. Estimates of variance of general combining ability were lower than those of variance of specific combining ability for all the traits e.g panicle number per plant (0.54), 1000 grain weight (1.50), harvest index (3.83) and grain yield per plant (17.09) showing preponderance of non-additive gene action except panicle length (1.28) and spikelet number per panicle(522.70) which showed high gca and indicated additive gene action. High estimates of broad sense heritability coupled with high genetic advance in mean percentage for Spikelet number per panicle (98 and 27.23 respectively). For grain yield per plant (98 and 14.38) and grain number per panicle (97 and 19.93) high heritability coupled with moderate genetic advance (98 and 14.38) indicated the scope of getting better recombinants. Selection will be more effective for the traits those have high heritability and high genetic advance.

Broad-sense heritability and variance component estimates for Pratylenchus brachyurus resistance in Brazilian soybean genotypes

Pratylenchus brachyurus has become one of the most serious problems in Brazilian soybean fields. The use of resistant cultivars has long been considered the most practical and effective means of controling nematodes. Nonetheless, to our knowledge, there is no study on the genetic parameters associated with resistance of soybean to P. brachyurus in Brazil. This study was undertaken to estimate resistance genetic parameters under glasshouse conditions. In both trials, we found high phenotypic and genotypic variability, either for reproductive factor or number of nematodes per fresh gram of roots. Furthermore, high coefficients of genotypic determination and variation index were obtained. These results suggest that breeding for this feature can be relatively easy. The next logical step will be to conduct inheritance genetic studies.

Exploring the Genetic Etiology of Trust in Adolescents: Combined Twin and DNA Analyses.

Behavioral traits generally show moderate to strong genetic influence, with heritability estimates of around 50%. Some recent research has suggested that trust may be an exception because it is more strongly influenced by social interactions. In a sample of over 7,000 adolescent twins from the United Kingdom’s Twins Early Development Study, we found broad sense heritability estimates of 57% for generalized trust and 51% for trust in friends. Genomic-relatedness-matrix restricted maximum likelihood (GREML) estimates in the same sample indicate that 21% of the narrow sense genetic variance can be explained by common single nucleotide polymorphisms for generalized trust and 43% for trust in friends. As expected, this implies a large amount of unexplained heritability, although power is low for estimating DNA-based heritability. The missing heritability may be accounted for by interactions between DNA and the social environment during development or via gene–environment correlations with rare variants. How these genes and environments correlate seem especially important for the development of trust.

PHYSIOLOGICAL AND GENETIC PERFORMANCE OF SOME RICE GENOTYPES GROWN IN MEDIUM AND HIGH SALINITY SOILS

Salinity is a common abiotic stress that seriously negatively affects rice production in the world. The investigation was carried out at the Experimental Farm of El-Sirw Agricultural Research Station, Damietta governorate, Egypt to investigate the effect of soil salinity levels (6 and 11 dS m-1) on the morphological, leaf chemical constituents and yield traits and phenotypic and genotypic parameters of twelve rice genotypes (Giza 177, Giza 179, Giza 182, Egyptian Jasmine, GZ 10303, GZ 10305, IET 1444, GZ 10286, GZ 9399, GZ 9461, PLGF101 and Egyptian Hybrid 1) during 2014 and 2015 seasons. The obtained results could be outlined as following: 1- The high level of salinity negatively affected growth parameters (leaf area index, dry matter production and chlorophyll content) and yield related characteristics (heading date, plant height, number of tillers hill-1, number of panicles hill-1, panicle length, number of filled grains panicles-1, 1000-grain weight, grain yield, biological yield and harvest index) in both seasons. It was detected that increasing salinity sharply decreased rice grain and biological yields with reduction percent amounted to 43.66 and 33.81 % for grain yield and biological yield, respectively. On the other side, increasing salinity significantly increased proline content, Na+ % and Na+/ K+ ratio while decreased K+ % in rice leaf. 2- The different genotypes were significantly varied among each other in their growth and yield. Egyptian Hybrid 1 surpassed other tested genotypes in growth parameters, number of tillers and panicles hill-1, panicle length, number of filled grain panicle-1 and grain and biological yields ha-1 in both seasons as compared with the other rice genotypes. On the contrary, the rice genotype of Giza 179 had the lowest unfilled grains panicle-1. The salt tolerant rice genotypes (Egyptian Hybrid 1, Giza 179, GZ 9399, GZ 9461 and IET 1444) had higher proline content and potassium % and lower Na+ and Na+/ K+ ratio, while the sensitive salt rice genotypes showed opposite pattern. 3- The interaction between the tested rice genotypes and salinity levels was significant for studied traits in both seasons. In general, Egyptian Hybrid 1 genotype was superior for the most growth and yield traits when it was grown on medium or high salinity levels followed by GZ 9399 and GZ 9461 genotypes. However, PLGF 101 genotype had the worst performance followed by GZ 10303 and Giza 177 rice genotypes. It could be concluded that Egyptian Hybrid 1 genotype had considerable affinity for withstanding salinity stress to tested levels under the experimental salinity conditions. The maximum reduction for grain yield (65.94 and 66.83%) was produced by planting Giza 177 and Giza 182 genotypes in the first and second seasons, respectively. However, the lowest reductions (23.59 and 18.85%) were obtained by growing Egyptian Hybrid 1 and GZ 9399 in the first and second season, respectively. 4- The phenotypic coefficient of variability (PCV) was slightly higher than those of genotypic coefficient of variability (GCV) for all studied traits of the twelve rice genotypes grown under the salinity levels. The value of GCV % was varied from 21.44 to 41.93 but in PCV% ranged from 23.68 to 52.99 for grain yield. In most characteristics the increasing salinity level raised the contribution of environmental variability in phenotypic variability. High heritability (H2%) estimates in broad sense were detected for most studied traits.

Genetic Variability for Yield and Nutritional Quality in Yam Bean (Pachyrhizus sp.)

The amount of genotypic and phenotypic variability that exists in a species is important for selection and initiating breeding programs. Yam bean is grown locally in tropical countries of the Americas and Asia for their tasty storage roots, which usually have low dry matter content. The crop was recently introduced in Uganda and other East and Central African countries to supplement iron (Fe) and protein content in diets. This study aimed to estimate genetic variability for root yield and quality traits among 26 yam bean accessions in Uganda. A randomized complete block design was used with two replications across two ecogeographical locations and two seasons during 2012 and 2013. Near-infrared reflectance spectroscopy (NIRS) was used to determine quality of storage root samples. Significant differences among genotypes were observed for all traits except root protein, zinc (Zn), and phosphorus contents. Genotypic variance components () were significant for storage root fresh yield (SRFY), storage root dry matter (SRDM), storage root dry yield (SRDY), vine yield (VNY), fresh biomass yield (FBY), and storage root starch (STA) and Fe contents. For traits with significant the broad sense heritability estimates ranged from 58.4% for SRDY to 83.6% for FBY; and phenotypic coefficients of variation were high for SRFY (66%), SRDY (53.3%), VNY (60.5%), and FBY (59%), but low to medium for SRDM (22.6%), STA (15.1%), and Fe (21.3%). Similarly, the genotypic coefficients of variation were high for SRFY (56.7%), SRDY (53.3%), VNY (55%), and FBY (53.9%); and low for SRDM (20%), STA (12.4%), and Fe (17.8%). There were strong positive correlations between SRFY and both SRDY (r = 0.926) and FBY (r = 0.962), but low-to-moderate correlations among quality traits. It should be possible to breed for high dry matter yam beans by using low dry matter accessions due to the observed genetic variation ( = 9.3%2), which is important if the high dry matter Pachyrhizus tuberosus accessions (known as chuin) from Peru cannot be accessed. This study indicated substantial genetic variation for yield and quality traits in yam bean, demonstrating potential for adaptability to growing conditions and consumer needs in East and Central Africa and for genetic improvement through selection.

Kemajuan Genetik dan Heritabilitas Karakter Agronomi Padi Beras Hitam pada Populasi F2

Black rice is a local rice variety with some advantages and weaknesses. The desirable character of black rice is its high anthocyanin content, while the weaknesses are late maturing, tall plant stature and low grain yield. Crosses were made between two parents aimed to recombine the superior traits. The effectiveness and efficiency of selection would be determined by the magnitude of the heritability of traits and the selection progress. This study was aimed to determine the heritability estimates in a broad sense and the genetic advance of agronomic characters of F2 generation, from crosses of local black rice and high yielding variety of white rice. The experiment was conducted in Padasan, Pakembinangun, Pakem, Sleman, Yogyakarta from January to May 2013. The F2 population derived from crosses of black rice x white rice, with the morphological traits of hairless black rice (S) crossed with Situbagendit (G) white rice, Cempo ireng (C) with Situbagendit (G) and Cempo ireng (C) with Inpari 6 (I). The F2 plants population were planted without replication. Genetic parameters estimated were calculated for broad sense heritability and genetic advance from selection. Results showed that the F2 population had high broad sense heritability estimates for all characters observed, including: plant height, flag leaf length, number of productive tillers, panicle length, number of filled grains per panicle, number of empty grains per panicle, maturity and rice color, in the three F2 populations obtained from crosses of S x G, C x G and C x I. Only the plant height of S x G cross had a medium broad sense heritability estimate. The large heritability estimates indicated that the respective character was controlled by genetic factor more than environmental ones. High genetic advance would be obtained in the flag leaf length, number of productive tillers, panicle length, number of filled grains/panicle, number of empty grains/panicle and rice color from S x G, C x G and C x I crosses. Genetic advance of plant height was medium (at S x G and C x I crosses) to high (C x G crosses). The maturity trait had low genetic advance on cross S x G; C x G; and Cx I. The high value of genetic advance of character would suggest that selection on the character’s appearance would be successful.

DETECTING AND ESTIMATION OF DIFFERENT COMPONENTS OF GENETIC VARIATION (ADDITIVE, DOMINANCE AND EPISTASIS) UNDER STRESS AND NON-STRESS CONDITIONS IN BREAD WHEAT

Twenty four common wheat varieties were used to establish the experimental materials for the two biometrical tools used in this concern i.e., triple test cross analysis and six populations analysis. Mean values of backcrosses to F1’s (L3i) showed increased in mean values and surpassed the other backcrosses for all traits studied, showing highly grain yield / plant and other yield contributed traits. It is clear that the backcrosses to L2 (Sids 12) tended to decreased in mean values for most traits showing low grain yield / plant with other yield attributes. On the other side, mean values of hybrids (L1, L2 and L3) surpassed lines in most traits indicating some sort of hybrid vigour. The means of lines and testers differed significantly from each other. The mean square for deviations L1i + L2i – 2L3i revealed presence of highly significant over all epistasis for all traits studied. The data revealed highly significant mean squares due to sums (L1i + L2i) for all traits studied. However mean square due to differences (L1 i- L2i) were significant only for 1000 grain weight, heading date, main culm spike length, number of spikelets / main culm spike, number of spikes / plant and plant height. The highest proportion of recombinants that possible outperform parental range was obtained for number of grains / spikelets followed by main culm spike length and main spike yield. These results reflecting fair amount of genetic variability and considered valuable further breeding studies aiming to improve such chatacters. Significant positive between epistasis gene effects controlling main spike yield and number of grain / main culm spike, and between number of grain / spikelets with number of spikes / plant. The main spike yield, main culm spike length, number of grains / main culm spike and number of spikeletes / main culm spike had a strong relation with grain yield. Dominance gene effects (d) were found to be significant in the four crosses for number of spikelets/main culm spike under 35kg.n./f only. The three epistatic types were found to be significant for most traits under investigation. High heritability estimates in broad sense were detected for nearly all traits studied. High estimates of narrow sense heritability were found for all crosses for heading date, plant height, number of spikes per plant, main culm spike length, number of kernels per spikelets, number of kernels per main culm spike and grain yield per plant under 35 kg.n./f. High genetic advance under selection was found to be associated with high narrow sense heritability estimates for number of spikes per plant and grain yield per plant for all crosses under 35 kg.n./f. for all crosses, number of kernels per spikelets under 35 kg.n./f. for third and fourth crosses.

ESTIMATION OF VARIANCES , GENOTYPIC AND PHENOTYPIC CORRELATIONS FOR SOME TRAITS OF MAIZE UNDER HIGHEST UNDUR NITROGEN ABUNDANCE

The objective of this study was estimation of variances, broad sense heritability genotypic and phenotypic correlation for some traits of maize under nitrogen abundance . the experiment was conducted at the farm of the Dept. of Field Crop Sci., College of Agric., Univ. of Baghdad during the Spring and fall seasons of 2012 under level 400 Kg N. ha rate-1 . Diallel cross was performed among four maize inbred lines (Zm7, Zm607, Oh40, Zr8) to produce six single crosses in spring season . The seeds of parents and crosses were sown in fall season using R.C.B.D. with three replicates. The results showed significant difference among genotypes and the values of the genotypic variance were more than environment variance in all studied characters. The values of phenotypic coefficients of variation larger than the genotypic and the higher rate of genotypic coefficient of variation for 300 grain weight 16.74, no. of grain per row 15.05 and leaves area 12.18. furthermore high estimates of broad sense heritability were observed for all characters and the highest value 81.45 for 300 weight grain and 75.31 for leaves area .The grain yield gave high significant negative genotypic and phenotypic with silking date and positive with plant height , leaves area , no. of grain per row , 300 grain weight. It was concluded that a breeder can use leaves area , no. of grain per row and grain weight as selection index in selection program of maize under high nitrogen

DETECTION AND ESTIMATION OF DIFFERENT COMPONENTS OF GENETIC VARIABILITY (ADDITIVE, DOMINANCE AND EPISTASIS) UNDER STRESS AND NON-STRESS CONDITIONS IN BREAD WHEAT 1- ESTIMATION OF GENETIC COMPONENTS UNDER TWO LEVELS OF NITROGEN FERTILIZATION IN TWO BREAD WHEAT CROSSES

This investigation aimed to study the potentiality of heterosis expression, heritability, expected genetic advance, nature of gene actions and potance ratio for some quantitative traits (grain yield and its contributory characters, heading date and plant height) in two bread wheat crosses Sids 1 x Gemmeiza 5 and Gemmeiza 9 x Sids 4 were chosen for the percent study on the base of wide variability. Six populations (P1, P2, F1, F2, BC1 and BC2) were used to estimate genetic parameters under two levels of nitrogen fertilization (35 kg N/fed and 70 kg n/fed). The results can be summarized as follows: The hybrid combination Sids 1 X Gemmeiza 5 was detected to be the highest cross showed significant useful heterosis for grain yield per plant (37.58% and 76.11%) under 35 kg.n. /f and 70 kg.N./f, respectively. Inbreeding depression values were found to be highly significant in most cases in the two crosses under investigation. 3. The F2-deviations (E1) were significant for plant height and number of spikelets / main culm spike for all crosses under the both of nitrogen fertilization levels. Also backcross-deviations (E2) were found to be significant for heading date, main culm spike length, number of spikelets / main culm spike and number of kernels per spikelet under the two levels of nitrogen fertilization. The additive gene effects (a) were found to be significant for heading date, plant height and 1000 grains weight for all crosses under investigation under the two levels of nitrogen fertilization. Dominance gene effects (d) were found to be significant in the two crosses for number of spikelets/main culm spike under 35kg.N./f only. The three epistatic types additive × additive, additive × dominance and dominance × dominance were found to be significant for most traits under investigation. High heritability estimates in broad sense were detected for nearly all traits studied. high estimates of narrow sense heritability were found for all crosses for heading date, plant height, number of spikes per plant, main culm spike length, number of kernels per spikelets, number of kernels per main culm spike and grain yield per plant under 35 kg.N./fed. High genetic advance under selection was found to be associated with high narrow sense heritability estimates for number of spikes per plant and grain yield per plant for all crosses under 35 kg.N./f. The breeder can use cross Sids 1 X Gemmeiza 5 in breeding programs that it has high heterosis for yield character and its components and high genetic advance under selection was found to be associated with high narrow sense heritability estimates for number of spikes per plant and grain yield per plant.

Association and path analysis in fenugreek (Trigonella foenum graecum)

Thirty fenugreek genotypes (Trigonella foenum graecumL) were evaluated during rabi season of 2012-13 to explore its existing gene pool and identify the selection indices with an eye on a more comprehensive breeding programme. Characters like number of pods per plant, protein content in seed, days to 50% flowering and dry weight at flower initiation were found to have least variation among the coefficients both at phenotypic and genotypic level. Broad sense heritability estimates were high for protein content in seed (96.9), followed by number of pods per plant (96.7). The highest genetic advance as percentage of mean was recorded for dry matter content and dry weight at flower initiation indicating that these characters are governed by additive gene action. Correlation coefficients at phenotypic and genotypic level envisaged that biological yield was having significant and positive correlation with chlorophyll content of the leaves, number of pods per plant, straw yield per plant, 1000 seed weight, dry matter content of the plant as whole and seed yield per plant while negatively correlated with the harvest index. Path coefficient analysis revealed that biological yield per plant, harvest index, dry weight at flower initiation, chlorophyll content in leaves, number of branches per plant and 1000 seed weight were the most important characters contributing towards seed yield and hence purposeful and balanced selection based on these traits would be more rewarding for improvement of fenugreek.

Genetic parameters and agronomic evaluation of cassava genotypes

Abstract: The objective of this work was to estimate genetic parameters and predict genetic values for the selection of cassava (Manihot esculenta) genotypes in the state of Pará, Brazil. The trial was performed with 56 genotypes in two growing seasons (2012/2013 and 2013/2014), in the municipality of Igarapé-Açu, in the state of Pará, using the augmented blocks design with two control treatments. The evaluated traits were: plant shoot weight (PSW), number of roots per plant (NRP), number of rotten roots per plant (NRRP), fresh root yield (FRY), harvest index (HI), and starch content in the roots (SCR). The restricted maximum likelihood (REML) and best linear unbiased prediction (BLUP) methods were used. There was genetic variability among genotypes for PSW, NRP, HI, and SCR. Broad-sense heritability estimates were low for PSW and SCR, but were moderate for NRP and HI. However, the heritabilities of the average of genotypes were higher for PSW and SCR. The genetic gains of the five best genotypes varied from 6.0 to 11.08% (PSW), 15.81 to 27.10% (NRP), 9.82 to 12.14% (HI), and 1.90 to 2.20% (SCR). There is genetic variability among cassava genotypes, and the possibility of genetic gains based on selection is moderate for this region in the state of Pará.

Genetic variability in Indian mustard (Brassica juncea L. Czern and Coss)

The data were recorded on five random selected plants for 12 quantitative characters and statistical analyzed. The analysis of variance for all the twelve characters is showed the mean square due to genotypes was highly significant. The mean values of various characters like days to 50 per cent flowering were recorded maximum for genotype IC560719 and Pusa Karishma (84.00 days)with mean 69.08 days The maximum days to 75% maturity were observed in IC-560700 genotype (142.00 days) with a mean of 135.07 days. The plant height highest recorded in the genotype IC-560696 (217.60 cm) with mean of 188.14 cm. The maximum number of primary branches per plant (16.47) was recorded in the genotype NPJ-113 with mean of 10.13. The genotype NPJ-113 produced maximum number of secondary branches per plant (35.47) with mean of 19.78. The maximum length of siliqua was recorded for Kranti (7.03) with mean of 5.24cm. The maximum number of seeds per siliqua was recorded in Kranti genotype (19.13) with mean value 14.91. The maximum 1000-seed weight recorded 5.57g for Pusa Jai Kisan with mean wt. 3.96 g. Pusa Mustard-21 produced highest biological yield (191.13g) with mean 79.00g. The genotype Pusa Jagannath had maximum harvest index (30.98%) with mean value 23.87%. The oil content in mustard maximum in 42.00 % were recorded in Pusa Agrani with mean oil content was 39.16 percent. The genotype Pusa Mustard-21 showed highest seed yield per plant (47.00g) with a mean seed yield of 18.58. The higher heritability estimates in broad sense for biological yield per plant (99.6%), number of primary branches per plant (91.4%), number of secondary branches per plant (98.4) plant height (99.2%), 1000-seed weight (99.4%) and days to 50 per cent flowering (98.5). Expected genetic advance at 5% selection intensity was recorded higher for biological yield per plant (71.60) and number secondary branches per plant (10.87).

English

Groundnut rosette disease is one of the most damaging diseases militating against groundnut production in sub-Saharan Africa. The disease cause up to 100% yield loss whenever epidemic occurs. The most effective, economic and environmental friendly method to control the disease is through genetic resistance. Knowledge on inheritance of resistance to the rosette disease is required to accelerate breeding of resistant varieties. A study was conducted to understand the nature and magnitude of gene effect of resistance to the disease. Thus F1, RF1, F2, RF2, BC1, RBC1, BC2, and RBC2 progenies were derived from crosses of Otuhia × Manipintar, Otuhia × Shitaochi, ICGV 01276 × Manipintar, and ICGV 01276 × Shitaochi along with their parents were evaluated in a randomized complete block design at CSIR - CRI, Fumesua, under artificial infection. Generation mean analysis revealed that additive gene action effect was predominant on the resistance to the disease in all the crosses. Additive by dominance was the only form of non-allelic interaction observed to be significant in ICGV 01276 × Manipintar cross. Reciprocal differences suggested the presence of maternal effect involved in the inheritance of resistance to groundnut rosette disease. Estimates of broad and narrow sense heritability indicated that genetic effect was larger than the environmental effects in this study. Disease diagnosis using TAS ELISA revealed the presence of groundnut rosette assistor virus (GRAV) antigens in the resistant samples analyzed. Resistant genotypes containing GRAV were considered to be resistant to the GRV and its Sat-RNA, but not the GRAV which causes no obvious symptoms by itself. Pure line breeding with selection from early generation is suggested for the improvement of resistance to rosette virus disease, because additive genetic effect contributed significantly in controlling the inheritance of resistance to groundnut rosette disease (GRD). Key words: Additive, dominance, heritability, inheritance, heterosis, rosette disease.

Field Evaluation of Potato Genotypes for Resistance to Powdery Scab on Tubers and Root Gall Formation Caused by Spongospora subterranea

Spongospora subterranea causes root galls and powdery scab on potato tubers (Solanum tuberosum L.). Host resistance represents an economically suitable and long term approach for the management of the disease; however, the relationship between root and tuber symptoms may vary across potato genotypes. To assess susceptibility differences among genotypes, 30 potato cultivars and 83 advanced clones with varying skin type (market class) were evaluated for powdery scab and root gall formation. Five field experiments were conducted during 2011 and 2012 on naturally infested soils in Minnesota and North Dakota. Differences among genotypes in the degree of susceptibility to tuber and root symptoms were observed (P < 0.001, n = 33 to 80). Higher powdery scab pressure (P < 0.001, n = 90) was observed in North Dakota locations across years. Environmental conditions influenced the formation of root galls and the expression of powdery scab, with greatest variability among white- and red-skinned genotypes. Under high disease pressure, the estimates of broad-sense heritability for powdery scab incidence and severity were 0.76 and 0.63, respectively. Across environments, russet-skinned genotypes resulted in less disease on tubers, but yielded similar levels of root galls as red-skinned genotypes. Tuber scab and root gall formation indices were significantly associated (r = 0.42, P < 0.001, n = 80); however, high levels of disease in roots were observed in genotypes ranked resistant to powdery scab. Cultivars Dakota Trailblazer, Dakota Russet and Karu ranked highly resistant, whereas Shepody, Kennebec and Red LaSoda were highly susceptible to both phases of the disease. Cultivar selection is highly recommended for disease management.

Efecto de la selección recurrente por sequía sobre el rendimiento y características agronómicas de líneas S1 de maíz (Zea mays L.) evaluadas en tres ambientes de Centro América, 1989

Breeding for adaptation to adverse environment should capitalize on additive genetic variance while simultaneously reducing genotype by environment interactions. In the present work, 400 S1 maize lines from a population resistent to drought from the Collaborative Regional Maize Breeding Project were evaluated under limited moisture conditions. These lines were evaluated in a lattice design of 20 x 20 with two replications per location in three different moisture environments. Selection pressure was 10%. Selection differentials for the selected fraction for recombination and experimental varieties were high. The selection differential was higher under limited moisture conditions confirming highly significant differences observed in the analysis of variance for lines. The experimental variety and the selected fraction had yield reductions with drought of 36%, in comparison to the population bulk which was reduced by 51 % with drought, demonstrating the efficacy of applied selection pressure. Within the variables studied, ears per plant correlated the highest with yield under limited moisture conditions. The anthesis-silking interval did not correlate as high with yield (interval of.8 to 5.9 days), possibly because the population had becn improved for this eharaetcristie. Estimatcd stability paramcters (β = 1 r = 0.9) identified the selected lines for synthctie varictics as stable cntries with a eonsistent response aeross the 3 moisture environments. Broad-sense heritability estimates (H2 = 0.43 and H2 = 0.64**) for yield and ears per plant under drought indieate that oneean expeet to obtain substantial selection progrcss by increasing the frequencies of favorable alleles which condition the hcritability of these characteristics.