Molecular characterization of groundnut (Arachis hypogaea L.) germplasm lines and varietal set for yield and yield attributing traits

The genetic assessment of 90 germplasm lines and six varieties of groundnut (Arachis hypogaea L.) were done with 13 morphological traits and 125 Simple Sequence Repeats markers. Out of 125 molecular markers, 26 were polymorphic and produced 105 alleles. The genetic diversity was found to be 52-83 per cent and Polymorphic Information Content (PIC) was 0.46-0.81 with a mean of 0.42 indicating higher magnitude of genetic diversity in the test genotypes. Analysis of molecular variance showed variation among and within individuals based on allelic variation. Principal Co-ordinate Analysis based on origin of the genotypes formed three major population groups and the genetic analysis determined by population structure divided all the germplasm lines in to 10 populations. Significant and positive correlation was observed between hundred kernel weight and hundred pod weight (r=0.769) and kernel yield (r=0.899); sound mature kernel and pod weight with kernel yield, weight of kernels and harvest index. Genotypes from distinct clusters may be selected in hybridization programme for groundnut improvement. The information on clustering of genotypes will be helpful in identification of novel and superior germplasm for hybridization and development of improved varieties.

Genetic variability, correlation and path coefficient analysis under drought in groundnut (Arachis hypogaea L.)

Groundnut yield in rain fed areas has been limited by drought stress because pod yield and other growth parameters have been severely affected. The aim of this study is to evaluate the genetic variability, character association and path analysis between yield and its contributing traits in 30 groundnut genotypes under drought. Analysis of variance revealed the existence of significant differences among genotypes for all characters studied. The magnitude of PCV and GCV was moderate to high for number of pods per plant, dry haulm yield, kernel yield, plant height and dry pod yield. High heritability coupled with high genetic advance as per cent of mean was observed for kernel yield, plant height, dry pod yield, and hundred kernel weight indicating the role of additive gene in expressing these traits. Dry pod yield was significant positively correlated with kernel yield, no of pods per plant, hundred kernel weight and SPAD chlorophyll meter reading (SCMR). Path coefficient analysis indicated that number of pods per plant and hundred kernel weight were essential traits to be considered for realizing the improvement in yield.

Analysis of chlorophyll content and its correlation with yield attributing traits on early varieties of maize (Zea mays L.)

Chlorophyll has direct roles on photosynthesis and hence closely relates to capacity for photosynthesis, development and yield of crops. With object to explore the roles of chlorophyll content and its relation with other yield attributing traits a field research was conducted using fourteen early genotypes of maize in RCBD design with three replications. Observations were made for Soil Plant Analysis Development (SPAD) reading, ear weight, number of kernel row/ear, number of kernel/row, five hundred kernel weight and grain yield/hectare and these traits were analyzed using Analysis of Variance (ANOVA) and correlation coefficient analysis. SPAD reading showed a non-significant variation among the genotypes while it revealed significant correlation with no. of kernel/row, grain yield/hectare and highly significant correlation with no. of kernel row/ear and ear weight which are the most yield determinative traits. For the trait grain yield/ha followed by number of kernel row/ear genotype ARUN-1EV has been found comparatively superior to ARUN-2 (standard check). Grain Yield/hectare was highly heritable (>0.6) while no. of kernel / row, SPAD reading, ear weight, number of kernel row/ear were moderately heritable (0.3-0.6). Correlation analysis and ANOVA revealed ARUN-1EV, comparatively superior to ARUN-2 (standard check), had higher SPAD reading than mean SPAD reading with significant correlation with no. of kernel/row, no. of kernel row/ear, ear weight and grain yield/ha which are all yield determinative traits . This showed positive and significant effect of chlorophyll content in grain yield of the maize.Journal of Maize Research and Development (2015) 1(1):134-145DOI: http://dx.doi.org/10.5281/zenodo.34263

Development of a set of compensating Triticum aestivum – Dasypyrum villosum Robertsonian translocation lines

Dasypyrum villosum (L.) Candargy, a wild relative of bread wheat ( Triticum aestivum L.), is the source of many agronomically important genes for wheat improvement. Production of compensating Robertsonian translocations (cRobTs), consisting of D. villosum chromosome arms translocated to homoeologous wheat chromosome arms, is one of the initial steps in exploiting this variation. The cRobTs for D. villosum chromosomes 1V, 4V, and 6V have been reported previously. Here we report attempted cRobTs for wheat – D. villosum chromosome combinations 2D/2V, 3D/3V, 5D/5V, and 7D/7V. The cRobTs for all D. villosum chromosomes were recovered except for the 2VS and 5VL arms. As was the case with the 6D/6V combination, no cRobTs involving 2D/2V chromosomes were recovered; instead, cRobT T2BS·2VL involving a nontargeted chromosome was recovered. All cRobTs are fertile, although the level of spike fertility and hundred kernel weight (HKW) varied among the lines. The set of cRobTs involving 12 of the 14 D. villosum chromosomes will be useful in wheat improvement programs. In fact, among the already reported cRobTs, T6AL·6VS carrying the Pm21 gene is deployed in agriculture and many useful genes have been reported on other cRobTs including resistance to stem rust race UG99 on T6AS·6VL.

Effects of weed "Reestablishment" after hoeing on corn yields

Some growers and researchers sustain the idea that regrowth or root setting of some weeds may occur after hoeing, with detrimental effects over corn. The objective of this study was to evaluate the effects of weed removal from the field, removal after each hoeing, and corn intercropped with gliricidia on weed control and corn yield values. The experimental design consisted of blocks with split-plots and six replicates. Cultivars AG 1051 and BM 2022, planted in the plots, were submitted to the following treatments: no hoeing, two hoeings (at 20 and 40 days after planting), and intercropped with gliricidia. The hoed plots were either submitted to weed removal after the first, second, or both hoeings, or remained without weed removal. In the intercropped treatment, gliricidia was sown by broadcasting at corn planting between the corn rows, at a density of 15 seeds m-2. Twenty-five weed species occurred in the experiment; the most frequent was Digitaria sanguinalis (family Poaceae). The weed control methods tested had similar effects on the cultivars, which were not different from one another with respect to the evaluated traits, except for one-hundred-kernel weight, with cultivar AG 1051 being superior. Weed removal did not influence green corn yield or grain yield. However, the number of kernels/ear was higher in plots where weeds were removed in relation to plots without weed removal, suggesting that weed removal might be beneficial to corn. Besides, a higher dry matter weight was obtained for the above-ground part of weeds removed from the field after the first and second hoeings than the weight of weeds removed after the second hoeing only which, in turn, was higher than the weight of weeds removed after the first hoeing only. Green ear yield, grain yield, and dry matter of the above-ground part of the weeds did not show differences in hoed plots and were superior to the non-weeded plots and the intercropped plots, which were not different from each other; therefore, intercropping with gliricidia did not improve corn yield values.