Varietal performance and correlation of okra pod yield and yield components
Abstract Field irrigation experiments were conducted to assess the varietal performance and correlation of pod yield and yield attributes under irrigation at the Teaching and Research Farm, University of Maiduguri, Nigeria, during the 2015 and 2016 dry seasons. The results revealed that the most outstanding for fresh pod yield per plant were okra cultivar Kwadag Y’ar gagure Salkade, and Kwadam, in descending order, with yield ranging from 580.38 to 622.67 g, while the Composite cultivar had the lowest value of pod yield of 428.62 g over the two years. The greatest average values for the number of pods per plant and the number of primary branches per plant were observed for Salkade and Y’ar gagure, respectively. Highest fresh pod length and fresh pod diameter were also exhibited for Salkade and Kwadag. The genotypic coefficient of variation was higher than the phenotypic variation for the entire yield-contributing characters. Days to 50% flowering were positive and highly significant differences associated with plant height, number of pods per plant, and fresh weight per pod could be observed. Path coefficient analysis showed that the number of pods per plant exhibited positive and direct influence on the pod yield across the studied years. Indirect influence of other yield components through this character also contributed mainly towards pod yield. Therefore, days to 50% flowering, plant height, pod length, number of pods per plant, pod diameter, number of primary branches per plant, and fresh weight per pod could be taken into consideration for the selection and development of high pod-yielding varieties in okra.
Selecting donor parents for future breeding aiming at tolerance to viral diseases with special emphasis on enation leaf curl virus in Okra
ABSTRACT Okra [Abelmoschus esculentus (L.) Moench] production is threatened by yellow vein mosaic virus (YVMV) and enation leaf curl virus (ELCV) diseases, of which ELCV has become prevalent and serious in the tropics. Identification of tolerance to ELCV among cultivated species of okra for utilization in breeding is lacking. The study was conducted to identify okra genotypes that can be utilized in hybridization to retrieve potential line(s) having degrees of tolerance against ELCV and YVMV, and which also exhibit high yield. Thirty-five okra genotypes, collected from different sources, were screened for tolerance to YVMV and ELCV and other quantitative traits. A wide range of variability occurred for the traits. No coincidence of YVMV and ELCV diseases occurred at the same time in any genotype. Genotypes were grouped into six distinct clusters emphasizing the relative contribution of various quantitative characters to total variability. The clusters do not represent place of origin indicating genotypes in a cluster were geographically diverse; genotypes obtained from the same region were genetically different. The principal components, Percent disease index (PDI) of YVMV, PDI of ELCV and plant height, had eigen values >1 and together accounted for 100% of total variation. Based on multivariate analysis and average values, genotypes ‘285-1-3A-1-17-1,’ ‘VRO-178,’ ‘285-1-3-1-15-2-1,’ and ‘12/OKYV RES-1’ were identified as potential donors that could be passed on to breeders for ELCV and YVMV disease resistant breeding, respectively.
Gut immunity in Lepidopteran insects.
Lepidopteran insects constitute one of the largest fractions of animals on earth, but are considered pests in their relationship with man. Key to the success of this order of insects is its ability to digest food and absorb nutrition, which takes place in the midgut. Because environmental microorganisms can easily enter Lepidopteran guts during feeding, the innate immune response guards against pathogenic bacteria, virus and microsporidia that can be devoured with food. Gut immune responses are complicated by both resident gut microbiota and the surrounding peritrophic membrane and are distinct from immune responses in the body cavity, which depend on the function of the fat body and hemocytes. Due to their relevance to agricultural production, studies of Lepidopteran insect midgut and immunity are receiving more attention, and here we summarize gut structures and functions, and discuss how these confer immunity against different microorganisms. It is expected that increased knowledge of Lepidopteran gut immunity may be utilized for pest biological control in the future.