The regeneration potential of pearl millet, a crop which is of vital importance for farmers in semi-arid tropical regions, was evaluated in a 12 × 12 line × tester cross involving six male sterile (A) lines from five systems of cytoplasmic-genic male sterility, namely two male sterile lines from system A1 (MS81A1, MS8A1), and one each from A2 (Pb313A2), A3 (Pb402A3), A4 (MS81A4) and A5 (MS81A5), the six corresponding maintainer (B) lines 81B1, 8B1, Pb313B2, Pb402B3, 81B4and 81B5, and twelve restorer (R) lines, namely H90/4-5, H77/833-2, G73-107, CSSC46-2, 77/245, 78/711, 77/273, ICR 161, ISK48, 77/28-2, 77/180 and Raj 42. The 24 parents and 144 crosses were grown separately in contiguous blocks in a randomized block design with two replications in three treatments each in 2000 and 2001 at the Research Farm, Bajra Section, Department of Plant Breeding, CCS HAU, Hisar. The plot size was 2.5 m × 0.45 m with 10 cm intra-row spacing. The genotypes (A lines, B lines, R lines, A × R crosses, B × R crosses), sowing dates, years, year × sowing date and genotype × treatment interactions (direct and reciprocal) exhibited significant differences. The comparison of mean performance of the early-sown non-ratooned crop vs. ratooned (cut, regenerated) vs. late-sown unratooned crop treatments revealed that both the grain and dry fodder yields and the major yield-contributing characters exhibited little reduction in the ratoon crop, while the total tillers at maturity and the effective tillers increased in the ratoon crop in comparison to the direct-sown crop. Additional green fodder yields of 189.63 g and 144.02 g per plant, harvested 40 days after sowing (DAS) in the ratoon crops in 2000 and 2001, respectively, and similar grain and dry fodder yields emphasized the utility of cutting and regeneration in pearl millet. The ratooning ability of genotypes, assessed from the ratio of the performance of various characters in ratoon and early and late sown unratooned crops for yield and major yield components was high for a number of lines, testers and hybrids. Most of the hybrids involved one or two parents with good regeneration potential. Sufficient genetic variability was observed for regeneration and ratooning ability, which was found to be under genetic control, suggesting that regeneration potential could be incorporated in genotypes with high yield. A base population developed from promising parents and crosses can be improved by cyclic breeding.
Among sucking insect pests, the incidence of a leafhopper [Amrasca biguttula biguttula (Ishida)] and a whitefly [Bemisia tabaci (Gennadius)] remained active through the cropping season in varying population density. Thrips [Thrips tabaci (Lindemann)] population was only observed in early stages of the crop growth. The leafhopper population attained its peak during 2nd half of July and was maximum (9.2 nymphs/3 leaves) in the year 2008. The population of whitefly adults was maximum (14.8 adults/3 leaves) in 2007 and it acquired its peak during end of July and again in end of September to early October. The incidence of thrips was maximum in June. The population of the A. biguttula showed significant positive correlation with minimum temperature (r=0.636; p=0.003), mean temperature (r=0.475; p=0.034), evening relative humidity (r=0.618; p=0.004) and rainfall (r=0.556; p=0.011). The correlation of B. tabaci population with minimum temperature was significantly positive (r=0.454; p=0.044). The multiple regression analysis revealed that all the weather parameters collectively accounted for variability in the A. biguttula and B. tabaci population with R2 values ranging from 0.67–0.80 and 0.50–0.69, respectively, during different years.
Authors:P. Sharma, H.K. Chaudhary, N.V. Manoj and P. Kumar
An investigation to standardize the protocol for in vitro application of colchicine for enhancing the doubled haploid production in wheat was done. Two tetraploid (PDW-314 and A-9-30-1); and two hexaploid (DH-40 and C-306) wheat genotypes were used as maternal parents, whereas, the pollen sources involved Zea mays (cv. Bajaura Makka) and Imperata cylindrica. During the rabi seasons of years 2013–14 and 2014–15, wheat × maize and wheat × I. cylindrica hybridization was carried out followed by treatment of their haploids produced as a result of elimination of chromosomes of maize and I. cylindrica respectively, with varied doses of colchicine for different durations The various doses of colchicine were categorized into two groups: lower doses for longer durations (0.01, 0.025, 0.05% each for 5, 7, 9, 11 hrs) and higher doses for shorter durations (0.05, 0.075, 0.10, 0.15, 0.20, 0.25% each for 5, 4, 3, 2 hrs). The response of different concentrations of colchicine applied for varied durations revealed significant differences for various doubled haploidy parameters viz., per cent survived plants, per cent doubled haploid formation and per cent doubled haploid seed formation. In hexaploid and tetraploid wheats, colchicine doses of 0.075% for 4 hrs and 0.15% for 4 hrs, respectively were established as optimum for enhanced doubled haploid production.
Genotype by environment interaction distorts genetic analysis, changes relative ranking of genotypes and a major obstruction for varietal release. AMMI model is a quick and relevant tool to judge environmental behaviour and genotypic stability in comparison to ANOVA, multiplicative model and linear regressions. We evaluated 19 barley genotypes grown at 08 diverse locations to identify discriminating environments and ideal genotypes with dynamic stability. In AMMI ANOVA, the locations and genotype by environment interaction exhibited 66% and 14.7% of the total variation. The initial first two principal components showed significant interaction with 36.0 and 28.4% variation, respectively. AMMI1 biplot showed that the environments Bawal, Ludhiana and Durgapura were high yielding with high IPCA1 scores and located far away from the biplot origin. However, in AMMI1and AMMI2 biplots the locations Hisar, Ludhiana, Karnal, Bathinda and Modipuram were found suitable with low IPCA2 scores. Yield stability index (YSI) was highly useful with ASV ranks and the genotypes DWRB150 and BH1013 and checks BH902, DWRUB52 and DWRB101 were selected for high grain yield and wider adaptability across the locations.
Authors:A. Mall, P. Swain, S. Das, O. Singh and A. Kumar
Twenty-four promising drought tolerant genotypes of IRRI and different parts of India were evaluated for genetic variability and drought susceptibility index (DSI) for 12 quality characters and grain yield under irrigated (E1) and drought (E2) conditions. In the present study differences among the genotypes are highly significant for all the characters; between the environments head rice recovery, alkali spreading value, water uptake, kernel length after cooking and yield were significant, while genotype × environment interaction was only significant for hulling, milling, head rice recovery and water uptake. Head rice recovery, alkali spreading value, water uptake and amylose content were observed to be governed by additive gene action under both the environments. Grain yield was positively correlated with kernel width and amylose content under stress environment while, kernel width was positively correlated with hulling and milling and kernel length was correlated with amylose content. The path coefficient analysis revealed that only kernel width in both the environments and amylose content in E2 had positive direct effect on yield. Most of the genotypes expressed low DSI value (<1) for yield and quality characters. However, Swarna and IR 78877-181-B-1-2 were identified as stable genotypes with low DSI value for seed yield and quality characters.
Authors:H. Khan, S.C. Bhardwaj, O.P. Gangwar, P. Prasad, P.L. Kashyap, S. Savadi, S. Kumar and R. Rathore
A set of forty wheat cultivars comprising bread wheat, durum and triticale identified during 2010–2014 were tested for resistance to Indian pathotypes of leaf, stem and yellow rusts at seedling stage under controlled conditions. Eight Lr genes (Lr1, Lr3, Lr10, Lr13, Lr14a, Lr23, Lr24 and Lr26) were characterized based on differential interactions with specific rust races. Genes Lr23, Lr26 and Lr13 conferred leaf rust resistance in most of the accessions. Three Yr genes (YrA, Yr2 and Yr9) were inferred in 40 genotypes, where Yr2 followed by Yr9 were most frequent in conferring stripe rust resistance. Ten Sr genes, namely, Sr2, Sr5, Sr8a, Sr7b, Sr9b, Sr9e, Sr11, Sr13, Sr24 and Sr31, were postulated in these lines with predominance of Sr11, Sr31 and Sr2. These Lr, Sr and Yr genes were observed singly or in combination. Robust DNA markers were used to identify adult plant resistance genes Yr18/Lr34/Sr57, Lr68 and Sr2 and all stage resistance genes Lr24/Sr24, Sr28 and Yr9/Lr26/Sr31. STS marker iag95 showed presence of Yr9 in four additional cultivars which were resistant to one or more rusts. Gene Sr28 was identified in seven durum cultivars with the wPt7004 marker. This is first report of Sr28 being present in many Indian wheat cultivars. CsGs-STS marker identified Lr68 in nine cultivars.
Authors:B. Kumar, K.S. Hooda, R. Gogoi, V. Kumar, S. Kumar, A. Abhishek, P. Bhati, J.C. Sekhar, K.R. Yathish, V. Singh, A. Das, G. Mukri, E. Varghese, H. Kaur, V. Malik and O.P. Yadav
Maydis leaf blight (MLB), a serious foliar fungal disease of maize, may cause up to 40% losses in yield. The present studies were undertaken to identify the stable sources of MLB resistance, its inheritance study, and testing of MLB resistance linked markers from diverse background in the Indian adapted tropical maize genotypes. A set of 112 inbred lines were screened under artificially created epiphytotics conditions at three hotspot locations. Analysis across multi-locations revealed significant effects of genotypes and environments, and non-significant effects due to genotypes × environment interaction on disease incidence. A total of 25 inbred lines with stable resistance were identified across multi-locations. Inheritance of resistance was studied in six F1s and two F2s of resistant and susceptible parents. The null hypothesis of segregation of resistance and susceptible for mono and digenic ratios in two F2 populations was rejected by Chi-square test. The non-significant differences among the reciprocal crosses depicted the complete control of nuclear genome for MLB resistance. Partial dominance in F1s and normal distribution pattern in F2s of resistant and susceptible parents suggested polygenic nature of MLB resistance. Correlation studies in F2 populations exhibited significant negative correlation between disease score and days to flowering. Five simple sequence repeats (SSRs) markers, found associated to MLB resistance in different studies were unable to differentiate amongst MLB resistance and susceptible parents in our study. This emphasizes the need of fine mapping for MLB resistance in Indian germplasm. The identified stable sources of resistance and information on inheritance study can be used further in strengthening of resistance breeding against MLB.
Authors:R. Batra, P. Kumar, M.R. Jangra, N. Passricha and V.K. Sikka
Adenosine diphosphate glucose pyrophosphorylase (AGPase) is the rate limiting enzyme of starch biosynthesis that directly affects the wheat productivity. AGPase and grain growth rate (GGR) discerned to be following strict temperature regimen in wheat disomic chromosome substitution (DCS) lines. The first half of grain filling period had chromosome 1B and 2D as prominent players, whereas second half was mainly controlled by chromosomes 6A and 5B. Chromosome 2D had major contribution towards yield in a specific temperature range of 23 ± 1.5 °C during initial stages of grain filling which can serve as an effective early screening tool for terminal heat tolerance in wheat. Chromosome 2D with highest amylose content can also be utilized to produce low digestibility flour. Grain yield was found to be significantly associated with spikes/plant, grains/spike, grain weight/spike and plant biomass. Further, path analysis indicated that though grains/spike had less direct effect on grain yield but its indirect impact on grain yield via AGPase-21 activity was high.
Authors:K.G. Mandal, K. Kannan, A.K. Thakur, D.K. Kundu, P.S. Brahmanand and A. Kumar
Three-year (2007/2008–2009/2010) field experiment was conducted at the Directorate of Water Management Research Farm under Deras command in Odisha, India to assess the crop yield, irrigation water use efficiency (WUE), sustainable yield index (SYI), land utilization index (LUI) and changes in soil organic carbon (SOC) for dominant rice systems, viz. rice-maize-rice, rice-cowpea-rice, rice-sunflower-rice, rice-tomato-okra and rice-fallow-rice. Results revealed that crop yield, in terms of total system productivity (TSP) increased by 273, 113, 106 and 58% in rice-tomato-okra, rice-sunflower-rice, rice-maize-rice and rice-cowpea-rice, respectively, when compared to rice-fallow-rice. Irrigation WUE was 49–414% greater in rice-based diversified systems than the existing rice-fallow-rice (2.98 kg ha−1 mm−1). The SYI ranged from 0.65 to 0.75 indicating greater sustainability of the systems. Three crops in a sequence resulted in greater LUI and production efficiency compared to rice-fallow-rice. The gross economic return and benefit-cost ratio was in the order: rice-tomato-okra > rice-maize-rice > rice-sunflower-rice > rice-cowpea-rice > rice-fallow-rice. The SOC storage ranged from 40.55 Mg ha−1 in rice-fallow-rice to 46.23 Mg ha−1 in rice-maize-rice system. The other systems had also very close values of SOC storage with the rice-maize-rice system; there was a positive change of SOC (7.20 to 12.52 Mg ha−1) for every system, with highest in rice-maize-rice system and the lowest in rice-fallow-rice. It is concluded that the appropriate rice-based system would be rice-tomato-okra followed by rice-maize-rice, rice-sunflower-rice and rice-cowpea-rice. Rice-fallow-rice is not advisable because of its lower productivity, lower LUI and economic return.
Authors:M. Sivasamy, M. Aparna, J. Kumar, P. Jayaprakash, V. Vikas, P. John, R. Nisha, Satyaprakash, K. Sivan and E. Punniakotti
Nearly twenty thousand wheat lines were phenotyped for the presence of leaf tip necrosis (LTN), a phenotypic trait linked to adult plant leaf rust resistance (APR) genes, viz. Lr34, Lr46 and Lr67 having pleiotropic association with multiple disease resistance genes. Thirty-six lines showed varied expression of LTN and moderate level of leaf rust severity at adult plant stage with slow rusting (disease progress at a retarded rate). Seedling resistance test (SRT) revealed susceptible and mixed infection types, a characteristic of adult plant resistance (APR) genes. Further molecular confirmation for the presence of these genes using available microsatellite markers revealed that of the 36 lines, five lines carried Lr46+ alone and five other lines carried Lr67+ alone. Seven lines carried the combination of Lr34+ and Lr67+ while six lines confirmed to carry the combination of Lr46+ and Lr67+. Remarkably three lines carried all the three APR genes, viz. Lr34+, Lr46+ and Lr67+. All these stocks can be a source of APR multiple disease resistance genes. Ten lines were not confirmed to carry any of the genes but still had LTN and SRT results showing an infection type typical of APR genes and these can be the source of identifying newer APR genes. The resistance based on minor APR genes when combined with a few additional minor genes in the background of high yielding cultivars is expected to have high level of race non-specific resistance and to be durable.