Abstract
The study on the physico-chemical and molecular characterization of chilli (Capsicum spp.) genotypes was conducted during 2010-2013 at Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur-1701. The study includes survey, evaluation and characterizations of physico-chemical, shelf-life and fruit parts of chilli for chilli industry and estimation of genetic diversity in landraces of chilli genotypes using SSR markers. The survey results indicated that majority of consumers and entrepreneurs preferred orange to red coloured dried chilli fruit, long slender, wrinkled and pungent chillies. The survey also indicated that medium sized fruits were preferred to long fruits because in storage they remained intact better than longer fruits, which tend to break at distal end. A fairly thin pericarp is necessary as drying of fruit can be more easily accomplished. On drying, fruits with thick pericarps show wrinkled surface and dull appearance. Bright red coloured chillies had higher price than those of dull red or even orange or yellow coloured chillies, besides deep red fruits tend to retain their colour in storage longer than those of light coloured ones. A total of 40 genotypes, including germplasm lines, landraces, cultivars and commercial varieties, were studied under field and laboratory conditions over two consecutive summer seasons. Twenty one genotypes were characterized for 79 parameters of plant growth habit to physico-chemical traits. Among the twenty one genotypes tested, ten genotypes G1, G10, G14, G15, G16, G17, G18, G19, G20 and G21 recorded significantly higher fruit yield per plant over the check. The genotypes G21, G19, G15, G17 and G16 were identified as sources of gene for the improvement of chilli yield. The genotype G7 showed the highest concentration of capsaicinoids (6,584.58ppm) and the genotypes G7, G3, G19 and G1 contained the maximum pungency level (82,368.24 to 1,06,011.74 SHU) and were suitable for capsaicin extraction processing industry. Besides, shelf-life study on green chilli genotypes was done at low and ambient temperature. The percent loss of weight of green chillies stored at low temperature (5-6°C) at the end of 56 days was 42.00-63.50%. At the end of 8 days of storage period, the percent weight loss of green chillies at ambient temperature (22.33.5°C) was 17.46-58.92%. Maximum loss was noticed in G11 and minimum in G21 which was suitable for export market. The maximum amount of edible pericarp was recorded in G21 (60.95%) followed by G3 (59.46%), G1 (57.15%) and G11 (57.14%). The genotypes G1, G3, G11 and G21 are suitable for producing high quality chilli powder for the processing industry. In different genotypes the range of non-edible seed and stalk were from 48.45 to 31.08% and 9.46 to 5.71%, respectively. The moisture content significantly differed with different genotypes of dry red chilli fruit. Fiber, fat, ash, ascorbic acid, capsaicin, total carotenoid, B-carotene, anthocyanin, total phenolic compound and tannin content were also found to differ in different genotypes. Different landraces of chilli genotypes were analyzed using eleven SSR primers. The SSR primers produced 42 SSR loci with an average value of 3.82 alleles per SSR locus. The similarity index matrix ranged from 0.0 to 0.88 (SSR). Polymorphic Information Content (PIC) values of the SSR primers ranged from 0.25 to 0.77 with an average value of 0.628. Based on similarity matrix using the Unweighted Pair Group Method of Arithmetic Means (UPGMA) dendrogram, twenty genotypes were grouped into 4 clusters. The resulting SSR dendrograms separated the landraces with small and erect fruit position from the large and medium fruited landraces with declining fruit position. SSR markers showed genetic variability in the studied chilli genotypes. Hybridization of cluster I with other clusters should be done to develop hybrid, as it was most divergent from other clusters.