The genetic parameters were studied to elucidate the genetic variability, correlation and path co-efficient analysis in thirty-nine genotypes of bottle gourd [Lagenaria siceraria (Mol.) Standl] in randomized complete block design with three replications. Observations were recorded for eleven quantitative characters viz., days to first male flower open, days to first female flower open, node number of first female flower, braches plant-1, days to harvest, number of fruits plant-1, fruit weight, fruit length, fruit girth, 100 seed weight and yield ton ha-1. The analysis of variance showed highly significant differences for all the characters studied indicating considerable variability among the genotypes. The highest GCV (35.57%) and PCV (35.62%) were observed for fruit length. The differences between GCV and PCV were high for fruit number plant-1 and days to first male flower open indicating environmental influences. High heritability associates with high estimates of genetic advance in percent of mean were noted for length of fruit, yield, girth of fruit and number of fruits plant-1. It indicated presence of additive gene effect and selection for these traits would be effective. Yield were positively and significantly correlated with fruit weight, 100 seed weight, branch plant-1 and number of fruits plant-1 .Negative associations of yield were noted with days to first male and female flower open, days to harvest and length of fruit. Path analysis revealed that fruits plant-1 (0.93) and weight of fruit (0.467) had very high positive effect on fruit yield ton ha-1 .Int. J. Agril. Res. Innov. & Tech. 8 (1): 14-17, June, 2018

An experiment on rapeseed/mustard genotypes was conducted during 2019-2020 rabi season in vinyl house of Plant Physiology Division of Bangladesh Agricultural Research Institute (BARI), Gazipur to find out the salt-tolerant genotypes based on the responses of their physiological parameters and yield. Five selected rapeseed/ mustard genotypes (V1= Jun-536, V2 = BJDH-12, V3 = BD-10115, V4 = BARI Sarisha-14, V5 = BD-6950) were tested at three salinity levels (S0= 0, S1= 5 and S2=10 dS m-1). Irrespective of the genotypes, salinity stress showed a negative effect on the measured physiological parameters as well as seed yield. Leaf chlorophyll contents, leaf area, leaf photosynthetic rate and total dry matter (TDM) were reduced due to salinity stress which ultimately affected seed yield irrespective of the genotypes. However, these parameters were less affected by the salinity in V1 and V2 genotypes compared to others. Sodium and potassium ion contents and their ratios (K+/Na+) in leaf tissues were significantly affected by salinity stress. Among the genotypes, V1 and V2 showed higher K+/Na+ ratios in leaf under both the salinity treatments, and that phenomenon indicated their higher tolerance to salinity than the other genotypes. Catalase (CAT), Peroxidase (POD) activity and Malondialdehyde (MDA) content of the genotypes increased due to salinity stress with variability among the genotypes. The higher CAT and POD activity with lower MDA content was found in V1 and V2 genotypes which indicated their better salt tolerance ability compared to others. These genotypes also showed higher seed yield under both the salinity levels (5 and 10 dS m-1) compared to other genotypes. Based on the responses of physiological parameters and seed yield to salinity, the genotypes Jun-536(V1) and BJDH-12(V2) could be considered relatively tolerant to salinity stress. Bangladesh Agron. J. 2021, 24(1): 43-55

Combining ability analysis provides useful information for the selection of parents, also information regarding the nature and magnitude of involved gene actions. Crops improvement involves strategies for enhancing yield potentiality and quality components. Targeting the improvement of respective characters in bitter gourd, combining ability and genetic parameters for 19 characters were estimated from a 6×6 full diallel analysis technique. The results revealed that the variances due to general combining ability (GCA) and specific combining ability (SCA) were highly significant for most of the important characters. It indicated the importance of both additive and non-additive gene actions. GCA variances were higher in magnitude than SCA variances for all the characters studied indicating the predominance of the additive gene effects in their inheritance. The parent P2 (BG 009) appeared as the best general combiner for earliness; P1 (BG 006) for number of fruits, average single fruit weight and fruit yield; P4 (BG 027) for node number of first female flower and days to seed fruit maturity; P3 (BG 011) for fruit length and thickness of the fruit flesh; P5 (BG 033) for 100-seed weight; and P6 for number of nodes per main vine. The SCA effect as well as reciprocal effect was also significant for most of the important characters in different crosses.

A pot experiment was conducted with three potato varieties [‘BARI Alu-72’ (salt-tolerant), ‘BARI Alu-25’ (relatively salt-tolerant) and ‘BARI Alu-13’ (saltsensitive)] under three levels of salinity stress (control; 0.2, moderate; 6-8 and severe; 10-12 dSm-1) for evaluating their morphological, physiological and biochemical changes during rabi season of 2018-19. Salinity treatment was imposed from 10 days after emergence (DAE) to maturity stage by adding NaCl solution. Salinity stress caused higher reduction in chlorophyll (Chl), carotenoids (CAR), cell membrane stability index (CMSI), biomass and tuber yield plant-1 but increase in contents of catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), glutathione peroxidase (GPX), glutathione S-transferase (GST) and glutathione reductase (GR) activities in all potato varieties and at all the salinity levels. The reduction of Chl, CAR, CMSI, biomass and yield plant-1 were lower in ‘BARI Alu-72’ as compared to other two varieties. Moreover, ‘BARI Alu-72’ showed higher activities of CAT, POD, APX, GPX, GR and GST as well as contents of K+ and lower malondialdehyde (MDA), lipoxygenase (LOX) and Na+ contents in comparison with those of ‘BARI Alu-25’ and ‘BARI Alu-13’. Activities of antioxidants were found moderate in ‘BARI Alu-25’. ‘BARI Alu-13’ showed higher Na+ and Na+/K+ ratio. The results showed that salinity tolerance in potato was manifested by lower decrease in biomass and yield plant-1 with higher antioxidant activities and K+ contents, and lower MDA, LOX and Na+ content than salinity sensitive genotype. Bangladesh J. Agril. Res. 45(3): 315-333, September 2020