Search

An investigation was carried out to assess the combining ability and nature of gene action in sweet corn genotypes using Line x Tester mating design using ten lines and five testers. Investigation on combining ability indicated the predominance of non-additive gene action for all the traits under study. The variance due to genotypes was highly significant among the parents and hybrids for all the traits studied. This result strongly suggests the utilisation of heterosis breeding methods to exploit hybrid vigour. The lines L1, L8, L7, L10 and testers T1, T5 had superior per se performance for yield and yield contributing traits. The results also revealed that, the lines L1, L7 and testers T1, T5 had high per se performance coupled with high gca for most of the yield attributing traits. Based on per se performance and sca effects, the hybrids L2 x T2, L1 x T1, L1 x T5, L7x T4and L4x T1 were found to be good. Among these hybrids,L2 x T2 was considered best because it recorded highest per se performance coupled with high sca for yield and yield contributing traits.

Phytic acid is an abhorrent anti-nutritional factor ascertaining several micronutrient deficiencies to monogastric animals by their chelating ability. Hence, screening of germplasm accessions by a rapid assay is necessary to identify the potential donors for low phytic acid in maize. This compound involves in a complex pathway inhabiting the role of several genes, establishes the difficulties in the molecular screening and elaborates the importance of an initial rapid assay in facilitating the screening of germplasm resources. Although, several methods have been followed for phytic acid content estimation, the direct estimation of phytic acid by Megazyme kit is found to be more precise than any other methods adopted. This Megazyme kit utilizes the natural phytase enzyme to liberate the free phosphorous from the samples and measures the phytate phosphorous content. But, estimating by this kit increases the cost of estimation while going for screening of a large number of samples. Thus an alternate rapid method that estimates the phytic acid content with a similar efficiency to this Megazyme assay has to be followed to facilitate the screening in a larger population. Among all the known methods, the Indirect assay described by Davies and Reid (1979) is found to be rapid and easy to be carried out in the initial screening of germplasm resources. Hence, a comparative study of phytic acid content estimated by these two protocols in a set of fiftyeight lines were subjected to a chi-square and paired t test. The phytic acid estimated by direct assay ranged from 2.04 to 15.59 mg/g and by indirect assay the range was observed from 2.77 to 16.70 mg/g. Although there were minor variations, there was not much difference observed between the two protocols. The chi- square test revealed a perfect goodness of fit between the protocols ( 2Calculated< 2 Table). Simultaneously, the paired t test between the means of phytic acid estimated from two protocols also exhibited a null difference (t calculated < t table) among them. Thus, we can conclude that the rapid indirect assay described by Davies and Reid (1979) could be effectively followed for initial screening of large number of germplasm accessions to identify the spontaneous donors of low phytic acid content in maize.

The current investigation was done to understand the role of phytic acid and its contribution to yield and yield attributing traits in maize. Phytic acid is an anti-nutritional factor involved in chelating phosphorus and other micronutrients in food. On contrary, it is a major regulator of the metabolic pathways in plants. This study involved the correlation and path analysis of nineteen morphological and two biochemical traits with phytic acid as the dependent factor. A significant positive correlation of seed girth, seed thickness, hundred seed weight, cob weight, starch content and single plant yield with phytic acid were observed. This elaborated the essentiality of phytic acid in seed set and pollination in maize. Consequently, this study also ensured the increase in free inorganic phosphorous content in reduced phytic acid lines through their negative association and revealed its chelating ability in foods. Further the path analysis established highest positive direct effect of single plant yield, seed girth, cob placement height, cob weight, days to 50 percent silking and cob girth towards the phytic acid content in maize. This reinforces the direct contribution of phytic acid in crop development. The correlation also encompasses the role of phytic acid in starch accumulation and seed thickness in maize by means of their positive association. Therefore, from this study it could be concluded that phytic acid has a functional relationship with the major yield contributing traits in maize. Hence proper selection criteria have to be followed for producing elite lines with low phytic acid in maize.

The present investigation was undertaken to study the frequency and spectrum of Chlorophyll mutations along with the mutagenic effectiveness and efficiency of different doses of EMS, Gamma ray and combination of both, in barnyard millet variety CO(Kv). 2. In M2 generation, no chlorophyll mutations were observed in the control population. The treatments behaved differently in the frequency of occurrence of chlorophyll mutations. The spectrum of chlorophyll mutations (chlorina, xantha, albino, viridis, and striata) were observed and grouped. Except striata, remaining four kinds of mutations viz., xantha, chlorina, viridis and albino were observed more frequently. The overall mutation spectrum showed that chlorina (0.47%) occurred with the highest frequency, followed by albino (0.37%), xantha (0.26%) viridis (0.19%) and Striata (0.08%). The mutagenic effectiveness decreased with the increase in dose of mutagen in both mutagens, indicating that negative relationship between effectiveness and dose of mutagen. Mutagenic efficiency (mutation rate in relation to M1 damage) in both mutagens was highest at the lowest dose and it decreased with the increase in dose. The study concluded that Barnyard millet, Co(Kv).2 millet responds well to EMS, Gamma ray and combination of EMS and Gamma ray treatments.

The number of genes controlling the traits and the nature of gene action are the important criteria for the selection of individual traits in a segregating population. The current study is focused to analyze the skewness and kurtosis in the backcross population of UMI1200β+ × HKI163 and UMI1230β+ × HKI163. The BC2F2 population showed positive skewness and platykurtic distribution for plant height. In the present study the dominant × dominant based complementary gene action played a role and more number of genes controlled the plant height. Hence, rigorous selection is needed to achieve the genetic gain in the later generation. The negative skewness and platykurtic distribution was recorded for single plant yield in UMI1200β+ × HKI163 which indicated the duplicate gene action and required mild selection to fix the individual traits for rapid genetic gain.

The present experiment was carried out to determine colchicine sensitivity in African marigold (Tagetes erecta)var. Pusa Narangi Gainda to various levels of colchicine (0.00, 0.02, 0.04, 0.06, 0.08 and 0.1%) at different duration of soaking (0, 1, 2 and 3 hours). The experimental results indicated that the effect of colchicine concentration and duration of treatment has a significant effect on morphological parameters of African marigold. Result showed gradual and significant reduction in germination percentage (40%), survival of seedlings (9%), shoot length (6.1cm), root length (3.2cm), leaf length (3.25cm) and leaf width (1.35cm) with the increase in concentration of colchicineat 0.1% for 3 hours of soaking. The probit curve analysis based on mortality percentage of treated seeds revealed, the LD50 dosage of colchicine to be 0.11% with a soaking duration of one hour for African marigold var. Pusa Narangi Gainda.

Genetic variability, heritability and genetic advance are the important factors which provides the knowledge about the nature of traits in breeding programme. The aim of this study is to estimate the genetic variability, heritability, and genetic advance in the backcross population of UMI1200β+ × HKI163 and UMI1230β+ × HKI163 to identify the individuals in the population with superior agronomic traits. Fourteen biometrical traits were analysed and thus revealed that all the backcross (BC1F1, BC2F1) and selfed (BC2F2) generations, phenotypic coeffiecient of variation is higher than the genotypic coefficient of variation. Highest heritability combined with genetic advance as percent of mean was observed in BC2F2 generation for 100 kernel weight (UMI1200β+ × HKI163) and single plant yield (UMI1230β+ × HKI163). Hence, the genetic gain of the individuals in the population are controlled by additive gene action.

The present study was carried out to determine the combining ability of six sweet corn inbred lines and their hybrids and to ascertain the association between different biometrical and quality traits for increased green cob yield in sweet corn (Zea mays con var saccharata). Six sweet corn inbred lines were used as parental lines and they were crossed in full diallel fashion. The resultant sweet corn hybrids and their parents along with check hybrid were evaluated in randomized complete block design. The SCA variance was found to be greater than GCA variance indicating the predominance of non additive gene action for all the characters studied. Highly positive sca effects were noticed in the hybrid 45683x45508 for cob placement height, plant height, cob length, cob breadth, number of kernels per row. The cross 45684x45508 expressed highly significant and positive sca effect for the most important trait, green cob weight and quality traits viz., total sugar and non reducing sugar and possibility of commercial exploitation of this hybrid to be assessed based on its stability. The traits viz., cob length, cob breadth, number of kernels per row and plant height had positive association with green cob weight which indicates the possibility of green cob yield improvement through selection in favour of these correlated traits.

Phytic acid is a major constraint in affecting the nutritional concerns of the people feeding on maize. Being a strong negatively charged chelator, this compound binds all the positively charged minerals like iron and zinc. It also acts as a major storage compound of phosphorous. Thus monogastric animals lacking phytase, fails to absorb these minerals and is considered as a antinutritional factor. This experiment was conducted to identify the potential donors for low phytic acid to produce hybrids with moderate phytic acid content. With this objective a reference set for phytate (2-16 mg/g) formed from a base population was screened. A D2 analysis in the reference set was done and this classified the genotypes into eight clusters. The genotypes with low phytate were grouped in cluster 4. Highest significant variability was observed for all the traits including phytic acid. Cob weight followed by phytic acid had a highest heritability with high genetic advance as percent of mean indicating the effectiveness of selection for these traits due to the presence of additive gene action. Among the six low phytate lines observed, UMI-113 had lowest phytate content of 2.77 mg/g. These six low phytate genotypes classified in cluster 4 were then selected as testers and were crossed to four elite lines. Among the 24 hybrids produced, three hybrids., UMI 1200 x UMI 1099, UMI 1201 x UMI 1099 and UMI 1210 x UMI 1099 yielded higher than the standard check with medium levels of phytic acid ranging from 10.23-10.46 mg/g. The line UMI-1099 was found be a good general combiner for yield related traits with a negative combining ability for phytic acid. Hence this line could be successfully used in low phytate breeding programs and these identified hybrids could be further used in poultry testing trials for analyzing the bioavailability of nutrients.

The present investigation was conducted to explore the genetic variability, character association and path analysis for yield and yield component traits in maize. One hundred maize inbred lines obtained from Department of millets,TNAU were raised along with five checks in Augmented block design II and observations were recorded on twenty morphological traits. Analysis of variance showed significant genotypic variance for all the characters. High PCV, GCV heritability and genetic advance as percentage of mean were recorded for anthesis silking interval, number of tassel branches, number of kernels per row, grain yield per plant, cob weight, ear height and number kernel rows per cob. This indicated the effectiveness of selection towards these traits. Critical analysis of results obtained from character association indicated that grain yield per plant had positive significant association with cob weight, cob girth, number of kernels per row plant height, cob length, ear height,100 kernel weight, tassel length and chlorophyll index. Thus selection for these traits could bring about an improvement in yield attributes of maize. Path analysis for the attributed traits revealed the direct influence of cob girth followed by number of kernels per row, shelling percentage, days to 50 percent silking and ear height on grain yield. Hence these traits could be used as an effective selection indicator to identify the elite genotypes from a population.

A set of forty-two maintainers and seventeen restorer lines were evaluated in RCBD(Randomized Complete Block Design) design during Kharif 2018 with a view of studying genetic parameters and association studies for eleven quantitative characters. Analysis of variance indicated that significant differences were observed for all studied characters in the experimental materials. The values of PCV were higher than GCV but in a narrow range indicating that the least influence of environment on the expression of traits. Estimates of high heritability coupled with high genetic advance as a percentage of mean were observed for the characters viz., leaf sheath length, leaf blade length, spike length, spike girth, plant height, 1000 seed weight and single plant yield suggesting that these characters are governed by additive gene action. Correlation and path analysis studies revealed that number of productive tillers/plant and 1000 grain weight could be considered as good selection indices for selecting genotypes for yield improvement.

Kodo millet accessions 103 numbers were evaluated and characterized for 21 qualitative characters. The traits viz., leaf character, leaf blade pigmentation, panicle exertion, spikelet arrangement on rachis, panicle appearance, spike curvature, degree of culm branching, degree of lodging, shattering and grain colour showed higher variation and thus exhibits scope for selection of traits useful for breeding programmes. The traits growth habit, leaf sheath pigmentation, sheath base pigmentation, leaf juncture pigmentation, internode pigmentation, flag leaf at the second primary axis node, nerves on glumes, spike branching, spikelet density, senescence and grain shape showed no variations. Cluster analysis was carried out which grouped the 103 accessions into 13 clusters. Cluster III was the largest cluster with 39 accessions followed by cluster VII with 21, cluster IV with 13, cluster I with nine, cluster X with six, cluster IX with four, cluster V with three, cluster II and VIII with two accessions each and clusters VI, XI, XII and XIII with one accession each. The genotypes within the same cluster considered to have the similar phenotypic characters. And the genotypes between the clusters are more diverse ones. Therefore, the genotypes of most diverse cluster may be used as parents in hybridization programmes to develop high yielding varieties.

Combining ability and heterosis analysis were performed in ten lines, five testers and their fifty hybrid combinations of maize using line x tester analysis. Combining ability analysis among the sixteen traits revealed significant line x tester interaction for most of the traits studied. Variance due to sca was found to be more than gca for all the traits studied which indicated the preponderance of non-additive gene action. Among the parents, the lines viz., N67, N10-65-3, N10-153-1-2 and the tester UMI 1210 exhibited higher per se along with positive gca effects and found to be good general combiners among the parents. Standard heterosis was calculated by comparing TNAU maize hybrid CO 6 as the standard check. Considering the per se, sca and standard heterosis, single cross hybrid N10-65-3 x E.No.8 was identified as the best hybrid for grain yield and other major yield contributing traits followed by the hybrid N44 x UMI 1221.

A genetic study in the F2 populations of three crosses viz, UMI1200 x UMI1099, UMI1201 x UMI1099 and UMI1210 x UMI1099 was carried out in Kharif 2017. The genetic parameters studied include genotypic and phenotypic coefficient of variances, heritability, genetic advance as percent of mean and correlation coefficient. Performance of the individual genotypes of all the three F2 populations for 17 traits including seed yield and phytic acid revealed the presence of significant difference among genotypes, indicating the presence of genetic variability. Marginal difference between genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) indicated that variability was due to genetic factors for most of the traits studied. Traits that exhibited high heritability along with high genetic advance as percentage of mean (GAM) which can be used for selection were identified. Association studies depicted that plant height, cob placement height, cob length, cob breadth, number of rows per cob, number of kernels per row, cob weight, hundred kernel weight and shelling percentage exhibited positive correlation with yield. Correlation between yield and phytic acid content was found to be non-significant in the current study which revealed that selection can be progressed in both directions independently and its possible to obtain inbreds with low phytic acid content and high yield in the later generations through effective breeding and selection strategies.

Genetic variability, heritability and genetic advance of a character assist in setting up the breeding programmes for the improvement of the particular trait. In the current study high estimates of PCV and GCV were recorded for cob weight and single plant yield among the cross derivatives of UMI 1200 × CE 477. The GCV estimates of single plant yield (23.28 in BC1F1, 38.10 in BC2F1 and 33.23 in BC2F2) was observed in the cross derivatives of UMI 1200 × CE 477. Higher PCV and GCV values were obtained for cob weight and single plant in the other cross UMI 1230 × CE 477 also. The GCV values for single plant yield (39.00 in BC1F1, 39.00 in BC2F1 and 37.11 in BC2F2) were found among the cross derivatives of UMI 1230 × CE 477. The PCV and GCV values suggested sufficient variability and thus offers scope for genetic improvement through selection. Both the characters cob weight and single plant yield exhibited higher heritability associated with high genetic advance and hence direct selection of such characters would be effective in improving the yield.

Heterosis and combining ability was studied in F1 hybrids of maize with respect to grain yield and yield attributing traits using twenty-two hybrids which were developed through Line × Tester mating design. The parents and their hybrids were subjected to assess the combining ability and nature of gene action governing the quantitative traits. The results inferred that the predominance of non-additive gene action was observed for all the traits. Among the parents, the overall study of gca effects suggested that parent UMI 1200-7-26-1-6-1, N 14, N 107 and N 285 were significant general combiner for yield, these can be used to improve hybrids with desirable traits in future. Significant positive SCA effects were found for all the studied traits. Among the hybrids, N 14 × UMI 1200-7-26-1-6-1 showed desirable standard heterosis percentage over the checks CO 6 and NK 6240 along with good sca effects and per se performance for grain yield and other important yield contributing traits over different locations thus it can be used for commercial seed production programme.

The immature hybrid embryos of five back crosses viz., (MCU 5 x G. armourianum) MCU 5, (MCU 5 x G. raimondii) MCU 5, (MCU 12 x G. raimondii) MCU 12, (TCH 1569 x G. armourianum) TCH 1569,(TCH 1609 x G. raimondii) TCH 1609 were excised 8 days after pollination and were cultured in various concentrations of auxin and cytokinin. To prevent boll shedding in all the crosses, growth hormones NAA 100 mg/l and GA3 50 mg/l was applied at the base of the pedicel for 8 days and then the ovules were excised and cultured on media to form calli. Out of different media combinations tried, maximum callus induction was observed in the medium containing IAA 2.0 mg/l, Kn 1.0 mg/l, CH 250 mg/l, AS 40 mg/l in all the crosses. Maximum response of callus induction was observed in the cross (MCU 5 x G. raimondii) MCU5.

Plants with high levels of antioxidant enzymes have been reported to have greater tolerance to this oxidative damage caused by salinity. Role of antioxidative enzyme activity in salt stress and screening maize hybrids for salinity tolerance was investigated in this study. A pot culture experiment was conducted to evaluate six maize hybrids (CO 6, CO 7, CO 8, CO 10, NK 6240 and 900M gold) for their tolerance to saline water irrigation. The maize hybrids were irrigated with saline water having a natural EC of 0.06, 3.2, 4.8, 6.2 and 8.9 dSm-1 for 30 days and replicated thrice in a FCRD. The antioxidant activities such as catalase (CAT), peroxidase (POX) and superoxy dismutase (SOD) were measured in maize hybrids grown under saline water irrigation besides recording and dry matter production (DMP) and growth attributes. CO 6 and CO 7 were identified as saline tolerant maize hybrids based on their antioxidant enzyme activities and DMP. However CO 8 has been observed as a salt sensitive maize hybrid as it showed lesser enzyme activities and DMP. The order of tolerance exists among the maize hybrids to irrigation water salinity were: CO 6 > CO 7 > NK6240 > 900M gold > CO 10 > CO8. Antioxidant enzyme activities and dry matter production were found to be useful traits for identifying salinity tolerance in maize hybrids at seedling stage.

Line × tester analysis was carried out involving fourty two lines and three testers in maize for assessing the combining ability for yield and its component characters. Hybrids recorded significant variance for all characters studied. Variance due to parents were significant for characters viz., days to 50% tasseling, days to 50% silking, plant height (cm), ear height (cm), cob length (cm), cob girth (cm), number of grain rows per cob, number of grains per row, number of grains per cob, 100 grain weight (gm) and grain yield per plant (gm). The variance due to sca was higher than gca indicating the predominance of non-additive type of gene action for the above mentioned traits. Among the lines, the line RML 12, was identified as the best general combiner with higher per se performance for most of the yield contributing traits followed by RML1, RML 26, RML 27 and RML 34. Considering the testers, RML 48 was found as the best general combiner with better mean performance for most of the yield contributing traits followed by RML 47. Among the crosses, RML12 x RML48 was found to be the superior with positive significant sca effects and better mean performance for grain yield, cob girth, number of grain rows per cob and no of grains per cob. Similar superior positive significant sca effects with better mean performance were also observed in RML26 x RML48 (no of grains per cob, grain yield per plant and grain yield per plot), RML27 x RML48 (grain yield per plant, grain rows per cob, grains per cob) and RML37 x RML48 (cob girth, hundred grain weight, grain yield per plant and grain yield per plot.

The experimental material comprised of one hundred and three germplasm accessions of kodo millet (Paspalum scrobiculatum L.) were evaluated to assess the genetic variability, heritability and genetic advance for fifteen yield component traits. Analysis of variance revealed that there were significant differences among the accessions for all the traits studied. The coefficient of variation at phenotypic (PCV) and genotypic (GCV) levels were high for Zn content, grain yield per plant, Fe content, number of productive tillers and thumb length. Broad sense heritability ranged from 54.18 per cent for length of the longest raceme to 97.30 per cent for days to 50 per cent flowering. High heritability coupled with high genetic advance as per cent of mean was observed for plant height, number of basal tillers, number of productive tillers, flag leaf width, inflorescence length, thumb length, Zn content, Fe content and grain yield per plant which indicates that these traits are under the influence of additive gene effects and selection may be effective for these characters.

A high yielding pearl millet variety, UCC 32 was developed as composite by mixing and random mating of five elite inbred lines with resistant to downy mildew disease at Department of millets, Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore. It has been tested extensively in Tamil Nadu and in other states under MLT, ART, OFT and All India Co-ordinated programme for the past four years. It performed well both under rainfed and irrigated situations in Tamil Nadu. This variety is medium in stature (160 -180 cm) and in duration (85 - 90 days). It produces 4 - 6 productive tillers with mostly lanceolate shaped ears. The size of the grain is bold and is grayish yellow in colour. The variety UCC 32 is highly resistant to downy mildew under both normal and sick plot condition. This new variety recorded a mean grain yield of 3474 kg/ha under irrigated conditions, which are about 17 and 23 per cent increase over the checks CO (Cu) 9 and ICMV 221 respectively. The mean grain yield under rainfed conditions is 2916 kg/ha which is 15 and 24 per cent increase over CO (Cu) 9 and ICMV 221 respectively. The variety UCC 32 is medium in duration, high yielding, resistant to downy mildew, bold grain, compact ear head, non-lodging and fertilizer responsive. The protein content is high (12.07 %). It has acceptable cooking quality and suited for consumption.

An experiment was conducted to estimate the lethal dose of the physical mutagen gamma ray in Kodomillet variety CO 3. Genetically pure seeds were treated with different doses of gamma rays viz., 100 Gy, 200 Gy, 300 Gy, 400 Gy and 500 Gy. Untreated seeds were used as check for comparison. The LD50 values were observed based on growth reduction of seedlings after gamma ray treatment. The LD50 dose for gamma ray under in vitro and in vivo condition was fixed 300 Gy based on probit analysis. As the doses of applied gamma ray increased, there was a decrease in germination, survival rate of seedlings, root length, shoot length, seedling height, vigour index under in vitro conditions and emergence and survival under field (in vivo) conditions in M1 generation as compared to the control.