The cucumber (Cucumis sativus L.) is one of the most important vegetables in Bangladesh as well as across the globe. However, many of the important cucumber landraces have disappeared in Bangladesh due to climate change, particularly erratic rainfall, extreme temperature, salinity, and drought. Therefore, to protect against the extinction of the cucumber landraces, we collected 103 landraces in different geographical regions of Bangladesh, including drought and saline-prone areas, and studied their divergence for the future breeding programme for the development of cultivars suitable for the climate-changing situations. Data on morphological features, yield, and its components, which include 17 qualitative and quantitative traits, were recorded during the observation. Among the cucumber landraces, the Shannon–Weaver diversity index analysis revealed the presence of genetic diversity in these landraces. The biggest diversity appeared in the fruit-related characteristics, i.e., stem end fruit shape, bottom end fruit shape, fruit shape, and fruit skin colour at the table and harvest maturity. The descriptive statistics and analysis of variance expressed a wide range of variability for quantitative traits. A broad phenotypic variation was also observed for traits such as yield plant−1 [CV (%) 31.88, ranges 0.96 to 3.11 kg] and fruits plant−1 (CV (%), 28.71, ranges, 2.58 to 9.75). High heritability (broad sense) coupled with a high genetic gain was observed for yield and yield-contributing characteristics, indicating that these characteristics are controlled by additive gene effects, and they are more reliable for effective selection. The phenotypic correlation studies showed that fruit yield plant−1 exhibited a positive and significant correlation with fruits plant−1, fruit length, fruit weight, fruit width, branches plant−1, and plant height. All landraces were grouped into six clusters, and the maximum number of landraces were accommodated in cluster VI (30), followed by cluster V (22), cluster III (22), cluster IV (14), cluster I (13), and cluster II (2). Comparing cluster means with studied traits revealed that cluster III with landraces AC-14, AC-97, AC-471, AC-451, and RAI-209 were more divergent for improving average fruit weight, fruit length, and fruit width. On the other hand, cluster IV with landraces AC-201, TT-161, RAI- 217, RAI-215, and TRMR-103 were more divergent for improving average vine length, internode length, and the number of primary branches plant−1, the number of fruits plant−1, and yield plant−1. According to the MGIDI index, AC-14 (G1), AC-201 (G7), AC-471 (G24), AC-97 (G30), RAI-215 (G68) and TT-161 (G 94) may be considered to be the best parents based on their qualitative and quantitative characteristics for the future breeding programme. Moreover, crossing between the landraces, which were collected from saline and drought areas, in clusters I, V, and VI with those in other clusters could produce suitable cucumber varieties for the climatic changing situation.
DNA fingerprinting and genetic diversity analysis helps direct selective breeding and conservation of plant species. Since simple sequence repeats (SSR) markers are co-dominant, they can predict level of genetic diversity and thereby protect plant genetic resources of a region. Keeping the aforesaid rationale in mind, we worked on molecular characterization of eight cotton varieties in Bangladesh using simple sequence repeat (SSR) or microsatellite DNA markers. All the three microsatellite DNA markers were found to be polymorphic, extracting a total of eight alleles with an average of 2.67 alleles per locus in the present study. Allele sizes were as 149-155 bp, 178-198 bp and 140-202 bp for the loci BNL1551, BNL1721 and BNL2960, respectively. Polymorphism Information Content (PIC) values were ranged from 0.469 to 0.531. UPGMA dendrogram separated 8 varieties of cotton into two clusters. One cluster contained six varieties CB-1, CB-2, CB-3, CB-7, CB-9 and CB-10 while other two varieties CB-5 and HC 1 formed another cluster. The findings of this study would provide a useful guide for selecting specific germplasm with distinct genetic background for diversifying cotton breeding program in Bangladesh.
Waterlogging is an illustrious abiotic stress and the constrictions it enforces on plant roots have negative effects on growth and development. This study was undertaken to investigate waterlogging stress tolerant potential in chilli (Capsicum annum L.) genotypes through evaluating morphological, physiological, biochemical and anatomical parameters. Thirty-five days old seedlings of 10 chilli genotypes were exposed to waterlogging stress maintaining water height 3-5 cm over the soil surface artificially for three days. This duration (36-38 DAE) was termed as waterlogging period, and subsequent withdrawal of waterlogging condition (39-45 DAE) was regarded as a recovery phase. Based on their survival performance, two tolerant genotypes viz., SRC-517 and BARI morich-2 and two susceptible genotypes viz., AHM-206 and RI-1(6) were selected for studying stress tolerance mechanism. Under waterlogging, however, both genotypes (tolerant and susceptible) exhibited reduced root shoot length, dry weight ratio, petiole weight and leaf area, and noticeable reduction regarding these parameters was observed in susceptible genotypes. Moreover, tolerant genotypes displayed a higher recovery than susceptible genotypes after removal of waterlogging stress. Lower reduction of leaf area and photosynthetic pigments as well as higher reduction of relative water content (RWC) were noticed in susceptible genotypes. Higher accumulation of proline and total antioxidant capacity (TAC) during waterlogging condition in tolerant genotypes suggested lower oxidative damage. Although both genotypes lost total soluble sugar (TSS) relative to control at waterlogging stress, better performance was recorded in tolerant genotypes. During the period after the removal of extra water, a similar genotypic response in terms of TSS gain was seen. Undoubtedly, under flooding conditions, the development of aerenchyma cells in tolerant genotypes is a means of tolerance mechanism for long-term survival. Thus, the morpho-physiological and biochemical changes help to understand the tolerance mechanism in chilli under waterlogging stress.
An experiment was conducted to study the in vitro culture of pointed gourd. Cotyledon rescued from physiologically matured seeds (PMS) and immatured seeds (IMS) of pointed gourd were used as explants. Cotyledon excised from PMS responded very well in all culture conditions. Plant regenerated from cotyledon of PMS ranged from 38 to 96% in different hormonal formulations of culture media. Highest percentage of shoot regeneration was observed in MS + 1.0 mg/l BAP and lowest in MS + 2.5 mg/l BAP. No plant regeneration was observed in cotyledon from immatured seeds. The highest percentage of root induction (99%) was achieved in half MS medium supplemented with 0.5 mg/l NAA. The regenerated plantlets were successfully established in earthen pot. Keywords: Cotyledon; in vitro; pointed gourd. DOI: 10.3329/bjar.v35i1.5874Bangladesh J. Agril. Res. 35(1) : 135-142, March 2010
Assessment of genetic diversity among different is a prerequisite for plant breeders in choosing potential parental lines. Ten genotypes of summer growing chilli including one released variety viz., BARI morich-2; one advanced line viz., SRC- 517 and eight local cultivars viz., IAH-160, IAH-164, AHM-206, AHM-217, AC-63, AC-312, RAI-67, and RI-1(6) were characterized with a view to explore genetic diversity within these genotypes based molecular markers. Using eight microsatellite (SSR) primers across 10 genotypes, a total of 30 alleles with an average number of 3.75 alleles per locus were found. The number of alleles detected varied form three (CAMS-864, CAMS-880, CAMS-885) to five (CAMS-647). The allele size ranged from 160 (CAMS-075) to 289 bp (CAMS-864). All most all sets of primers showed high polymorphism (PIC value ≥0.6) except CAMS-880 and CAMS-885 which suggesting the greater genetic diversity in the genotypes. Gene diversity ranged from 0.460 (CAMS-885) to 0.740 (CAMS-647) and the highest and lowest value of Shannon's Information Index was registered in the same locus with their average value of 1.174. Higher level of genetic differentiation (0.971) and lower level of gene flow value (0.007) which were indicative of the presence of diversity among the genotypes. The genotypes had distinct status in the dendrogram, because of variation in genetic distance values differed from 0.138 to 0.938. SAARC J. Agric., 20(2): 69-82 (2022)
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