GENERATION OF SALT TOLERANT AND HIGH YIELDING GENOTYPES OF GROUNDNUT (Arachis hypogaea L.) THROUGH INTERVARIETAL CROSSES

Abstract

In order to develop salt tolerant and high yielding groundnut genotypes four separate experiments were carried out during the period from August 2010 to January 2014. Of which experiment 1 and 2 were conducted at the net house premises of Sher-e-Bangla Agricultural University (SAU), Dhaka; and experiment 3 and 4 were conducted in the field experimental plot of SAU campus, Dhaka and Agricultural Research Station, Bangladesh Agricultural Research Institute, Benarpota, Satkhira, respectively. To screening the salt tolerant and sensitive genotypes the study was conducted based on sixteen characters of 25 genotypes of groundnut at different salinity levels of 10dS/m, 8dS/m and control tap water 0.38dS/m. From the study it was found that shoot-root characters were reduced with the increase of salinity levels. The yield and yield attributing characters were reduced with the increase of salinity levels. In shoot tissues up take of Na+ and K+ content (%)/plant increased with the increase of salinity, but Ca++ up take increased with the increase of salinity up to 8 dS/m and reduced again with the increase of salinity at 10dS/m level. On the basis of % reduction of shoot biomass, total biomass, pod number, pod yield and kernel yield under salinity six genotypes were selected viz. Binachinabadam-5 as tolerant; Binachinabadam-2 and Binachinabadam-6 as moderately tolerant, BARI Chinabadam-6 and BARI Chinabadam-5 as moderately sensitive and Dhaka-1 as sensitive. To study the combining ability and the nature of gene action the selected seven diverse genotypes were crossed in half diallel fashion and their 21 F1 progenies along with their parents were evaluated in pot culture with saline soil. The significant variation in general and specific combining ability estimated for all the characters were observed which indicated the importance of both additive and non-additive gene actions in inheritance of these characters. The characters are controlled either by additive x dominant or by dominant x dominant type gene interaction and thus non-fixable. Wr-Vr analysis showed absence of nonallelic interaction for the expression of total biomass, pod number, pod yield and kernel weight. The genetic studies of all traits is appeared to be controlled by poly genes (two to five groups) with preponderance of dominance effect and the genes with positive and negative effects followed asymmetrically distribution amongst the parents. Pod yield, kernel weight and pod number had highest, higher and moderate narrow sense heritability respectively. This means simple progeny selection could be effectively followed in the segregating generations for these traits under salinity. The genotypic effects and comparative performance of F2 7x7 diallel population in experiment 3and 4 showed the presence of wide range of variation among the genotypes for all characters in non-saline and saline field condition, respectively. In nonsaline field condition cross P2xP5 showed the highest pod yield per plant followed by cross P4xP6, P5xP7, P5xP6, P1xP7, P4xP7 and P3xP7. In both field conditions, moderate to high estimates of heritability along with high genetic advance in percentage of mean for pod yield and yield contributing traits suggests that improvement of these would be further progressed through selection. The F2 crosses P2xP3, P1xP2, P2xP4, P1xP3, P2xP6 and P2xP5 as the most salt tolerant genotypes could serve as a source of genetic material for the improvement of high yielding salt tolerant varieties in saline field condition.