Commercial Hybrid Varieties Research Articles

Infestation of Spodoptera frugiperda on corn in Bengkulu at different elevations

Pest infestation is a significant challenge in corn cultivation due to the potential damage it can cause, leading to reduced crop productivity or even complete crop failure. This study aims to assess the infestation of Spodoptera frugiperda on corn in Bengkulu, considering various elevations. Ten hybrids resulting from crosses between promising lines (Caps 2 x Caps 17A, Caps 3 x Caps 17A, Caps 3 x Caps 17B, Caps 5 x Caps 22, Caps 5 x Caps 17B, Caps 15 x Caps 22, Caps 17B x Caps 23, Caps 17A x Caps 17B, Caps 17A x Caps 22, Caps 22 x Caps 23) and three commercial hybrid varieties (Bonanza, Paragon, and Secada) were evaluated across three locations at different elevations: lowland (30 meters above sea level) (masl), midland (600 masl), and highland (1000 masl). The assessment focused on the extent of damage and the plant’s resistance to S. frugiperda infestations. The infestation of S. frugiperda is higher at an elevation of 30 masl compared to locations at 600 masl and 1000 masl. Scoring leaf damage caused by S. frugiperda infestation at 30 masl: 2.73–4.86, at 600 masl: 2.73–3.55, and at 1000 masl: 2.4–3.37.

Morphological parameters, heritability, yield component correlation, and multivariate analysis to determine secondary characters in selecting hybrid maize

Abstract. Fadhli N, Farid M, Azrai M, Nur A, Effendi R, Priyanto SB, Nasruddin AD, Novianti F. 2023. Morphological parameters, heritability, yield component correlation, and multivariate analysis to determine secondary characters in selecting hybrid maize. Biodiversitas 24: 3750-3757. Direct selection for grain yield traits in maize (Zea mays L.) is often inefficient under specific conditions, necessitating the accurate determination of secondary traits to facilitate implementation and enhance selection precision. This study aimed to examine the morphological parameters, heritability, yield component correlations, and multivariate analysis of hybrid maize for determining potential secondary traits through indirect selection. The experimental design employed a randomized complete block design (RCBD) comprising 17 genotypes, including 15 hybrid maize lines and 2 hybrid maize varieties (RK 457 and RK 57). The results revealed that weight of harvested cob character and yield traits demonstrated significant correlations with production. Correlation values were further analyzed using biplot analysis and path analysis to identify potential secondary traits. The principal component biplot analysis results indicated four characters as effective secondary traits for selection, namely weight of harvested cob, yield, weight of 1000 seeds, and moisture content. MSM53/BCY as a parent of JHD 05 displayed superior performance compared to the two commercial hybrid varieties. Based on path analysis results, the weight of harvested cob character exhibited the highest direct effect on production with a value of 0.93, indicating that weight of harvested cob is the best secondary trait for selection.

Nectar Dynamics and Pollinators Preference in Sunflower.

Simple SummaryThe survival of pollinators is in real danger, and the reasons are due to climate change, inadequate pesticide use, invasive species and diseases. The nectar produced by plants is the basic food for many of these insects, together with pollen. However, the scarcity of nectar secretion in certain plant species is becoming alarming, especially in recent years. We focused our study on sunflower species, a plant which is an object of debate within the scientific community for the strong industrial interest, but also for the decline in pollen, nectar and honey production displayed globally in recent decades. We tested a commercial hybrid variety in different soil conditions and verified nectar secretion and quality. We also evaluated the pollinator visiting habits using the same hybrid in comparison with a non-hybrid variety. Our findings point out the effect of compost with respect to nectar composition and the pollinators preference toward the non-hybrid variety.Nectar is a complex biochemical substance secreted with particular rhythm by flower nectaries. Nectar is the base of a mutualism in which pollinators consume nectar, as food source, and are involuntarily responsible for the transport of pollen and pollination. The dynamics and temporal patterns of nectar secretion are still not fully understood as well as the environmental and climatic factors influencing its production. The quantity and quality of nectar found in standing crops at flowering influence the mutualistic relationship with pollinators and their foraging behavior. This situation is even more significant considering the reduction in undisturbed environments, the loss of soil quality, the spread of monoculture agricultural management and the use of self-fertile hybrids. The objects of the study are understanding the relationship among soil properties and nectar quality, comparing the nectar composition in a sunflower hybrid variety and evaluate pollinator preferences in selecting nectar sources among hybrid and non-hybrid varieties. For these purposes, two different experimental tests were established. Results highlighted that fertilization strategy influenced crop biomass development, determined soil characteristics and nectar composition in Sunflower. However, when comparing nectar composition of hybrid and non-hybrid varieties of sunflower, no significant differences were found. Despite this, the analysis of number of visits on the two treatments showed statistically significant differences. This research provides further understanding of the very complex relationship among soil, crop and nectar to support the definition of agricultural management strategies and reach the optimal nectar composition level for pollinators in agricultural crops.

Three-way cross white kernel hybrid maize out-yielded commercial variety tested under two contrasting environments

Despite the souring demand in the poultry industry, a larger proportion of the population in mid-hills is still dependent on maize as a staple food. Maize kernel color has a great influence on its end use; yellow is preferred for poultry feeds, and white for human consumption. The popular white kernel improved maize has a low yield potential and the majority of high yielding hybrids have yellow kernels. Considering these facts, we evaluated twenty maize genotypes, including 19 three-way cross white kernel hybrid maize (CIMMYT hybrids) and one commercial hybrid (RMH4642- Indian origin), in an alpha lattice design with two replications during the winter and summer seasons of 2017 and 2018 respectively. The main objective was to identify high potential white kernel hybrid maize with consistent performance in both the summer and winter seasons. In this study, we evaluated genotypes based on grain yield, disease resistance, and consistency in contrasting environments. The majority of the tested three-way cross hybrid genotypes out-yielded commercial checks in both seasons. The yielding potential of the top hybrids ranged from 7.89 to 9.76 t ha −1 across seasons. CLTHW16173, CLTHW16037, CLTHW16032, and CLTHW16012 were identified as stalk rot resistant genotypes with a disease incidence of less than 10%. AMMI (Additive main effects and multiplicative interaction) analysis revealed that genotypes CLTHW16116, CLTHW16003, CLTHW16037, and CLTHW16009 showed consistent performance with higher average grain yield across the seasons. These outstanding hybrids need to be tested in farmers’ fields at different agro-ecologies under varied growing seasons to validate their performance. • Maize Kernel color influences the end use; yellow for livestock feeds and white for human consumption. • White kernel improved varieties are low potential and majority of high potential hybrids has yellow kernel. • Three way cross white kernel maize out-performed commercial hybrid variety in both the seasons and top genotypes yielded within the range of 7.89–9.76 t ha −1 . • CLTHW16116, CLTHW16003, CLTHW16037, and CLTHW16009 yielded consistently with higher average across the seasons.

Uncertainty and learning in a technologically dynamic industry: Seed density in U.S. maize

AbstractThe large and sustained yield gains achieved since the introduction of maize hybrids in the 1930s (about 1.8 bushels per acre per year) have been accompanied by a remarkably parallel and steady increase in seeding density. This increase occurred in an environment characterized by rapid technological innovation, including genetic engineering, and commercial hybrid varieties with short life cycles. An important question, then, is whether and how breeders and farmers have learned about the optimal planting density. In this paper, we use unique and detailed U.S. farm‐level data, consisting of more than 400,000 planting choices from 1995–2016, to assess the nature of learning about seeding density. Importantly, we control for unobserved confounders through both hybrid and farm‐level fixed effects. We find that the variance in planting rates for a given hybrid has decreased over time, and that farmers tend to plant a given variety at higher rates over time. This is consistent with Bayesian learning in which risk‐neutral farmers possess priors consistently below the true optimal rate. We cast doubt on risk aversion as a credible explanation for this finding by analyzing the contrasting evolution of soybean planting rates (a crop with exogenously different agronomic determinants of seed density). We interpret our results as evidence of inertia: the initial bias in maize farmers' priors is tilted towards the optimal planting rates of varieties planted in the past. One implication of the finding that farmers historically underinvested in seeding rates is that eliminating this tendency could result in productivity gains.

Combining ability of S3 maize inbred lines and related contributing traits for high yield under high population density

The productivity of maize may be increased by using maize hybrid ideotype (erect leaves and small leaf angles) which is adaptive under high plant population density. The hybrids maize was desirable in increasing the plant density due to better light interception and space so that it can increase the yield per unit area. The aim of the research was to assess S3 lines that had good combining ability and to determine the traits associated with high yields under high plant population density (83.333 plants/ha). A total of 242 hybrids (F1) were examined from a crossed combination of 121 lines x 2 tester were evaluated with three commercial hybrid varieties such as Bisi 18, P 27, and P 36. The evaluation was carried under high plant population density (83,333 plants/ha) in the rainy season (November 2020 – February 2021). The research used an alpha lattice design with three replications. The results showed that the inbred lines had a greater effect on the yield character and yield components, while the leaf angle and leaf orientation effected by the tester. The lines that had good general combining ability for high yielding were M3B11P27T3-11-3-1, P27M3B11T3-1-4-2, P27M3B11T3-1-2-1, M3B11P27T3-8-4-1, P27M3B11T1-7-1-1, M3B11P27T1-1-1-3. The yield range of the hybrids were 8.43-9.90 t/ha, significantly higher than Bisi 18, P 27, P 36 varieties were 7.13 t/ha. Traits such as small leaf angle, erect leaf, root and stem lodging resistance, stem diameter, leaf length, ear diameter, and kernel row number were significantly correlated with high yield under high plant population density.

Genetic potential of tropical sweet corn hybrids and combining ability among parental inbred lines

Superiority of sweet corn (Zea mays L. saccharata) hybrid varieties is reflected by their performance per se, heterosis they reveal and combining ability of their inbred parents. This study was conducted to investigate performance, combining ability, heterosis and heritability revealed by 15 F1 tropical sweet corn hybrids from a half-diallel cross involving six diverse inbred lines, at two locations in Malaysia. At each location, the hybrids were evaluated for ear yield and yield components in a randomised complete block design, in comparison with their inbred parents and a commercial hybrid variety Hybrid 530 as control. Hybrids H11, H12 and H15 were found to be the most superior for yield and yield components, hence could be further tested in large-scale trials before release. Inbred lines FTT-1, EE0-2 and HAW-1 showed high positive GCA effects for yield and yield-related traits at both locations. Cross combinations HAV-2 × NTS-2, HSE-4 × NTS-2, NTS-2 × EE0-2 and EE0-2 × HAW-1 revealed high positive SCA effects for fresh ear yield and yield related traits at both location. Crosses among unrelated lines were found to produce superior hybrids. Both additive and non-additive gene effects were found important, although additive effects were predominating. The hybrids revealed substantially high heterosis, the highest being for number of ears per hectare and ear height. Moderate to high broad- and narrow-sense heritabi1ity estimates were displayed by the different traits measured

Morpho-molecular Divergence of Restorer Lines for Hybrid Rice (Oryza sativa L.) Development

Genetic diversity of 28 restorer lines of rice was studied under irrigated condition through Mahalanobis D2 statistics and simple sequence repeat (SSR) banding patterns. The cluster analysis grouped the lines into five clusters. The principal component analysis showed that the first four components with vector values > 1 contributed 76.32% of the total variations. The intra- and inter-cluster distances were the maximum in cluster V (0.86) and between clusters II and V (15.14), respectively. Flag leaf area, plant height, panicle length, five panicle weight, primary branches per panicle and secondary branches per panicle had maximum contribution towards genetic divergence. A total of 24 alleles varied from 2 to 5 with an average of 2.67 alleles per locus were detected for the nine microsatellite markers across 28 lines. The polymorphism information content (PIC) values ranged from 0.12 to 0.71 with an average of 0.29. RM229 was considered as the best markers on the basis of the highest PIC value. Phylogenetic cluster analysis of the SSR data based on distance divided all lines into three groups (A, B and C), whereas the cluster analysis divided these lines into five groups (I, II, III, IV and V). Besides, evaluation of yield contributing traits demonstrated that the restorer lines under the current study possessed a considerable genetic diversity. Potential lines such as BU1IR, China2R, China1R, BHD3R, IR509R and Heera5R can be used as pollen parent in developing new commercial hybrid varieties. Therefore, potential restorer lines need to be conserved in Genebank for future hybrid rice breeding programs.

Identification of high-efficiency SSR markers for assessing watermelon genetic purity

Genomic simple sequence repeat (SSR) markers were used to fingerprint and determine genetic similarity (GS) of the watermelon breeding lines, as well as the purity of their hybrid derivatives. Cluster analysis and Jaccard's distance coefficients using the unweighted pair group method with arithmetic mean (UPGMA) have classified these lines into three major groups. Notwithstanding,the genetic background of these lines is narrow as revealed by the restricted GS coefficients. Fifty-five sets of SSR markers were employed in this study. Fourteen of these markers were polymorphic between the breeding lines and were used for assessing hybrid purity. Cross-checking assay validated nine SSR markers as informative SSR markers for purity detection of these hybrids. To confirm the accuracy and efficiency of these markers, their derived PCR products were further sequenced, and ClSSR09643, ClSSR18153 and ClSSR01623 were selected as high-efficiency SSR markers. Interestingly, SSR markers ClSSR09643 and ClSSR18153 were broadly applied for purity detection of more than two different hybrids, while SSR marker ClSSR01623 behaved as a specific marker forpurity detection in this study. Genetic purity of six commercial watermelon hybrids was definitely evaluated using these SSR markers. Genetic purity of all tested hybrids exceeded 96% while the field purity was above 98%. Genetic purity test was an emergency for identifying off-types and selfed female in a lot of hybrid seeds. Here, we elucidated the potential of nine SSR markers including threewith higher breeding selection efficiency. We recommended them to seed company for purity improvement of watermelon commercial hybrid varieties.

Evaluation of Genotype x Environment Interaction and Stability of Grain Yield and Related Yield Components in Pearl Millet (Pennisetum glaucum (L.) R.Br.)

Thirty six pearl millet genotypes were evaluated in randomized complete block design with two replications during 2011/2012 at two locations to study the magnitude of genotype by environment interaction for yield and yield related traits and identify the most stable high yielding genotypes. ANOVA of data at individual locations revealed significant differences among genotypes at Marigat and Koibatek for all yield components. Combined mean analysis of variance showed that the Genotype and location main effects and the genotype by environment interaction were highly significant (P≤0.01) for grain yield and other traits, indicating differential response of genotypes across testing locations and the need for stability analysis. Marigat was the most suitable environment and gave highest mean grain yield of 3620 kg/ha. The lowest yield 870 Kg/ha was recorded at Koibatek. Genotypes EUP 32, EUP 35, EUP 19 and EUP 10 produced high mean yield of 3530, 3080, 2690 and 2590 kg/ha respectively. The lowest grain 1290 kg/ha was obtained from genotype EUP 4.Based on the parameters of stability, three stable (widely adapted) and high yielding genotypes (EUP 34, EUP 18, and EUP 9) were identified. They also out-yield the standard open pollinated variety (OPV) check, Kat PM2. Genotypes EUP 32 was the highest yielding across all sites followed by EUP 35 and could be recommended for further multi-location evaluation in warmer environment and possible release for commercial production. The findings of this study showed that pearl millet hybrids have high potential for commercial production in Kenya than the OPVs. The ANOVA results showed that the effects of environments, genotypes and genotype x environment interaction (GE) were important in trait expression and performance of genotypes. In addition, it was observed that amount of rainfall received at both vegetative and post-anthesis phases and temperature had an effect on grain yield. The GGE biplot analysis characterised the environments in terms of stability and productivity, where Marigat was the best for grain yield; implying that environment-specific selection should be adopted. Genotypes EUP 34, EUP 18, and EUP 9 were the best performing since they out yielded the standard OPV check. These stable high yielding genotypes can be evaluated further in varied agro-ecologies and recommended for release as commercial hybrid varieties in ASALs of Kenya.

Grain-yield stability among tropical maize hybrids derived from doubled-haploid inbred lines under random drought stress and optimum moisture conditions.

Drought is a devastating environmental stress in agriculture and hence a common target of plant breeding. A review of breeding progress on drought tolerance shows that, to a certain extent, selection for high yield in stress-free conditions indirectly improves yield in water-limiting conditions. The objectives of this study were to (i) assess the genotype × environment (GE) interaction for grain yield (GY) and other agronomic traits for maize (Zea mays L.) across East African agro-ecologies; and (ii) evaluate agronomic performance and stability in Uganda and Tanzania under optimum and random drought conditions. Data were recorded for major agronomic traits. Genotype main effect plus GE (GGE) biplot analysis was used to assess the stability of varieties within various environments and across environments. Combined analysis of variance across optimum moisture and random drought environments indicated that locations, mean-squares for genotypes and GE were significant for most measured traits. The best hybrids, CKDHH1097 and CKDHH1090, gave GY advantages of 23% and 43%, respectively, over the commercial hybrid varieties under both optimum-moisture and random-drought conditions. Across environments, genotypic variance was less than the GE variance for GY. The hybrids derived from doubled-haploid inbred lines produced higher GY and possessed acceptable agronomic traits compared with the commercial hybrids. Hybrid CKDHH1098 ranked second-best under optimum-moisture and drought-stress environments and was the most stable with broad adaptation to both environments. Use of the best doubled-haploids lines in testcross hybrids make-up, well targeted to the production environments, could boost maize production among farmers in East Africa.

Keragaan Agronomi dan Potensi Hasil Genotipe Jagung (Zea mays L.) Generasi S1 dan S2 di Dua Lokasi

Hybrid maize breeding relies on the availability of good performing inbred lines with superior combining ability. The objectives of this study were to: (1) estimate genetic paramters and heritability for agronomic and yield traits, (2) estimate correlations among traits, and (3) estimate selection-balanced inbreeding depression level from S1 to S2 generations. The S1 trial was planted from June to September 2014 at two locations, followed by the S2 trial from January to May 2015 at the same locations. Each trials was arranged in an augmented design with three blocks consisting of 72 unreplicated test genotypes, 3 unreplicated inbred lines, and 5 replicated commercial hybrid varieties as checks. The results showed that the heritability estimates were medium to high for most observed traits. Best yielding genotypes in S1 and S2 generations were derived from P27xNK6326, Pertiwi3xP31, NK6326xP31, P31xNK6326, and P31xNK33 populations. Grain yield was positively correlated with plant height, ear height, ear length, and ear diameter in S1 and S2 generations. The S2 generation exhibited inbreeding depression for grain yield. The estimates of heritability, correlations, and inbreeding depression obtained from this study could be useful for selection in corn breeding programs.<br /><br />Keywords: correlation, heritability, inbreeding depression<br /><br />

Evaluasi Stabilitas Hasil Jagung Hibrida Menggunakan Metode Genotype and Genotype by Environment Interaction Biplot (GGE BIPLOT)

<p class="Abstrak">Visualization of GGE biplot analyses was able to explain the genotype by environment interaction. This research was aimed to determine the yield stability of promising experimental maize hybrids in eight locations based GGE biplot method. Ten promising experimental maize hybrids and two commercial hybrid varieties as check, namely: HBSTK01, HBSTK03, HBSTK05, HBSTK06, HBSTK07, HBSTK08, HBSTK09, HBSTK10, HBSTK11, HBSTK13 and Bima 16 and Pertiwi 3 were evaluated in eight locations, ie. Bangka (Bangka Belitung), Probolinggo (East Java), Minahasa Utara (North Sulawesi), Donggala (Central Sulawesi), Soppeng, South Sulawesi, Gowa (South Sulawesi, Konawe (Southeast Sulawesi)and Lombok Barat (West Nusa Tenggara) from May to October 2013. The treatments were arranged in a randomized complete block design (RCBD) with 3 replications. Variable measured was grain yield. Analysis of variance was performed for data from each study site, to determine the performance of each genotype at each location. Yield stability analysis was performed by GGE biplot method using PB tools software. Results showed that genotype H9 (HBSTK11) had the highest biological stability with grain yield of 10.37 t/ha, higer than the overall mean yield. The best hybrid with the highest yield and good stability was hybrid H6 (HBSTK08) of 11.08 t/ha. This experimental hybrid is considered potential to be released as new hybrid variety. North Minahasa is considered the most suitable location for testing, whereas Konawe and West Lombok are least suitable, compared with the other locations.</p>

Daya Gabung Inbrida Jagung Toleran Cekaman Kekeringan dan Nitrogen Rendah pada Pembentukan Varietas Hibrida

<p class="Abstrak">Low maize grain yield due to drought and low N stresses maybe overcome by growing tolerance hybrid maize varieties.<strong> </strong>The objectives of this research were to analyze the combining ability of eight inbred lines possessing those traits and indentify suitable parental inbred lines which can be used to develop single cross hybrid tolerant to drought and low nitrogen. Eight inbred lines were crossed using complete diallel cross design of Griffing’s- I on Februry to June, 2014. Those inbred lines were 1044-30, DTPYC9-F46-3-9-1-1-B (for drought tolerance), MR 14 (medium drought tolerance), G20133077 (tolerant to low N), CY 11, CLRCY039 (medium tolerant to low N), and CY12 and G2013631 (for drought and low N sensitive). Fifty-six experimental hybrids derived from diallel crosses, eight inbred lines and four commercial hybrid varieties as checks were evaluated under managed drought, low dosage of N fertilization and under optimum condition, during the dry season (July to October) of 2014. Randomized complete block design three replications was used in each different stress condition. The results showed that CY 11, G2013631, and MR 14 inbred lines possesed good general combining ability (GCA) for grain yield under drought, low N, and optimum conditions. These inbred lines also showed good GCA for the secondary traits such as large stem, delayed leaf rolling and late leaf senescence to support for high grain yield under drought stress and low N condition. Inbred lines of drought and low N sensitive such as G2013631, but had high GCA, could be used as parent to develop drought and low N tolerance hybrids if crossed with inbred lines having medium-tolerant to drought or tolerant to low N, such as G20133077, which had low DGU, or CY11 which had high GCA. Hybrid maize tolerant to drought and tolerant to low N, such as CY11 x G20133077, G20133077 x G2013631, and CY 11 x G2013631, produced significantly higher grain yield, over 8 t/ha, under drought and under low N, as compared with hybrid varieties Bima 3 and Bisi 2, which yielded 5.91 and 6.59 t/ha under drought, and 6.82 and 7.01 t/ha under low N condition. Grain yields under optimum condition were positively correlated with those under both drought and low N conditions. The result suggests that it is possible for improving grain yield of hybrid maize, simultaneously for optimum, drought stress and low N conditions.</p>

Evaluation of Tomato Cultivars for Central Tarai of Nepal

Tomato (Lycopersicon esculentum L.) is an important winter vegetable crop in Central Tarai. As compared to India (25 t/ha), the productivity of this crop in this area is quite low (17 t/ha). One of the major contributing factors of low productivity of tomato is the lack of suitable high yielding varieties under rice based cropping system. Ten tomato cultivars, 3 released check cultivars (Pusa ruby and CL-1131 open pollinated and Srijana hybrid cultivar), 7 superior cultivars from Initial Evaluation Trial in the past were planted in November 2005, 2006, 2009 and 2010 at RARS Parwanipur in rice-based cropping system. The trial was laid out in a randomized complete block design with four replications. Seedlings were transplanted on beds at 60x60 cm spacing fertilized with 120:100:60 NPK + 15 t compost per hectare. Results showed that cv. HRDTOM-005XHRDTOM-010 (30.64 t/ha) followed by Makis (28.90 t/ha) and cv. Srijana (28.87 t/ha) gave higher yield among the tested cultivars. These cultivars had given 47.0%, 38.7%, and 38.5% more yield as compared to commercial hybrid variety Manisha (20.84t/ha) whereas Bari-4 and CL-1131 had superior performance among the tested open pollinated cultivars. On the basis of overall performance, cultivars, HRDTOM-005XHRDTOM-010, Makis and Srijana hybrid cultivars, and Bari-4 and CL- 1131from open pollinated cultivars were selected and recommended for cultivation in central Tarai.DOI: http://dx.doi.org/njst.v15i2.12105 Nepal Journal Of Science and Technology, Vol. 15, No. 2, 2014, 11-16

Genetic dissection of tomato rootstock effects on scion traits under moderate salinity.

Rootstock HKT1 genotype affected fruit [Na(+)] and non-commercial fruit yield; QTL analysis of rootstock-mediated scion nutrition is a powerful forward genetic approach to identify wild genes for rootstock breeding. The present study approaches the QTL dissection of rootstock effects on a commercial hybrid variety grafted on a population of RILs derived from Solanum pimpinellifolium, genotyped for 4370 segregating SNPs from the SolCAP tomato panel and grown under moderate salinity. Results are compared to those previously obtained under high salinity. The most likely functional candidate genes controlling the scion [Na(+)] were rootstock HKT1;1 and HKT1;2 as it was previously reported for non-grafted genotypes. The higher fruit [Na(+)] found when rootstock genotype was homozygote for SpHKT1 supports the thesis that scion HKT1 is loading Na(+) into the phloem sap in leaves and unloading it in sink organs. A significant increment of small, mostly seedless, fruits was found associated with SlHKT1 homozygous rootstocks. Just grafting increased the incidence of blossom end rot and delayed fruit maturation but there were rootstock RILs that increased commercial fruit yield under moderate salinity. The heritability and number of QTLs involved were lower and different than those found under high salinity. Four large contributing (>17%) rootstock QTLs, controlling the leaf concentrations of B, K, Mg and Mo were detected whose 2 Mbp physical intervals contained B, K, Mg and Mo transporter-coding genes, respectively. Since a minimum of 3 QTLs (two of them coincident with leaf K and Ca QTLs) were also found governing rootstock-mediated soluble-solids content of the fruit under moderate salinity, grafting desirable crop varieties on stress-tolerant rootstocks tenders an opportunity to increase both salt tolerance and quality.

Combining ability study in waterlogged tolerant maize (Zea mays L.)

Combining ability was studied for kernel yield and yield components in a 8×8 diallel cross of waterlogged tolerant maize. Significant general and specific combining ability variances were observed for all the characters studied. Additive genetic variance was preponderant in plant height, ear height, ear length, ear diameter, and kernel weight and non-additive gene action was involved in days to silking, number of kernels per ear and kernel yield. The parental lines E-31 and E-79 were found to be the best general combiners for yield. The good combining parents for different traits could be used in hybridization to improve yield and other desirable traits as donor parents for the accumulation of favourable genes. The cross combinations, E 31× E 40, E 31× E 64, E 31× E 79, E 38× E 40, E 58× E 79, E 63× E 79, E 64 × E 79 showing significant and positive sca effects can be used for commercial hybrid variety development after verifying them at different locations. DOI: http://dx.doi.org/10.3329/bjar.v39i2.20430 Bangladesh J. Agril. Res. 39(2): 283-291, June 2014

Assessment of Genetic Diversity in Sugarcane Germplasm Using ISSR and SSR Markers

Molecular diversity within and between Saccharum species clones and elite commercial hybrid varieties was studied using intersimple sequence repeat (ISSR) and simple sequence repeat (SSR) markers. The present study was performed to characterize 81 sugarcane genotypes. A total of 13 ISSR primers used and produced 65 amplified fragments, of which 63 (96.5 %) were polymorphic. The Polymorphic Information Content (PIC) value ranged from 0.11 (UBC824) to 0.45 (UBC825) primers with an average value of 0.28. The primer UBC 817 and UBC 825 exhibited highest resolving power (Rp) value 3.8 among thirteen primers. Genetic similarity (GS) by Jaccard’s similarity coefficient ranged from 0.23 to 0.95 with a mean of 0.59. Of the 79 alleles amplified by 28 SSRs primers showed 76 alleles, which were found to be polymorphic (96.2 %). The PIC value ranged from 0.06 (VSICRAD4) to 0.55 (VSICRAD26) primers with an average value of 0.17. The primer VSICRAD23 exhibited highest resolving power (Rp) value 4.3 among 28 primers. The GS by Jaccard’s similarity coefficient ranged from 0.11 to 0.91 with a mean of 0.51. Dendrograms constructed using the UPGMA cluster analysis revealed low level of correlation between genetic similarities based on pedigree and DNA profiles. The ISSR and SSR amplification proved to be valuable method for assessing genetic diversity among sugarcane complex and their related wild varieties and for identification of the cultivars.

Possibilities of Development of Red Rot Resistance in Sugarcane Through Somaclonal Variation

Red rot behavior of 50 somaclones of sugarcane variety CoS 88230, was studied by plug and nodal methods of inoculation using a mixture of four isolates of Colletotrichum falcatum. The results revealed that most of the somaclones had red rot susceptibility to varying degrees except four somaclones viz. SC-15, 20, 22 and 30, which were found moderately resistant (MR) by plug method of inoculation. Two somaclones viz. SC-22 and 30 were found resistant by nodal method of inoculation. Using plug method of inoculation, the aforesaid four somaclones viz. SC-15, 20, 22 and 30 were also found moderately resistant against all the four strains if tested individually, according to 0–9 scale except against isolate R 8411. These somaclones were better in red rot resistance than the donor variety CoS 88230. The wide variations observed in a number of traits along with red rot behavior in the somaclonal population was possibly due to complex genetic nature and existence of chromosomal mosaicism in commercial hybrid varieties of sugarcane.

427 Inheritance of the Albino Trait in Daylily

The albino genetic characteristic is a lethal condition in the post-seedling stage in plants. Although, it is an undesirable genetic characteristic, it is however an interesting genetic condition that can be utilized as a good practical genetic exercise for plant genetic and breeding courses. In this study, four commercial hybrid varieties of Hemerocallis were crossed as followed: A) “Stella D'ora” (with light orange flower) × “Happy Return” (with yellow flower); B) “Dark-eyed Magic” (purple with pink/cream variegated flower) × “Stella D'ora” (yellow flower). The seeds from these crosses were harvested and germinated in a plastic flat containing metromix 500 soil medium and placed under greenhouse condition. The germination of the seeds from each of the crosses resulted in the expression of green and albino seedlings in the F2; showing the typical Mendelian segregation of a dihybrid cross. Green was found to be dominant to albino. All the albino seedlings withered and died 2 weeks after germination. All four commercial hybrid varieties are carrier of the albino recessive gene.