Heritability and gene effects for salinity tolerance in cucumber (Cucumis sativus L.) estimated by generation mean analysis

Cucumber production is greatly reduced by high salinity. Our recent identification of cucumber genotypes with relative tolerance to salinity provides the potential for development of salt tolerant cultivars if the mode of inheritance for this trait is known. In this study, two cucumber parental lines, 11411S (P-1, salt tolerant), 11439S (P-2, salt sensitive) were crossed to study gene actions responsible for inheritance of salinity tolerance (TOL), relative leaf number (RLN14), area of second largest fully expanded leaf (LA) and vine length (VL) under saline growing conditions. The six populations denoted as P-1, P-2, F-1, B-1 (F-1 x P-1), B-2 (F-1 x P-2) and F-2 (F-1 x F-1) were subjected to 80 mM NaCl stress in greenhouse pot experiments and data subjected to generation mean analysis. Epistatic gene effects on all the traits were not detected by A, B, C scaling test while joint scaling test showed the presence of non-allelic interactions for all the traits. TOL and RLN14 were predominantly under additive gene effect while inheritance LA was largely influenced by dominance and additive gene effects. Dominant gene effect significantly controlled the inheritance of VL. The narrow sense heritability for TOL, RLN14, VL and LA was 0.57, 0.26, 0.74 and 0.66, respectively. VL and LA registered significant positive heterobeltiosis. The presence of dominance gene effect and low heritability of photosynthesis enhancing trait, RLN14 makes it impractical to improve salinity through simple selection or pedigree breeding. Simultaneous selection for RLN14 and TOL in segregating population at advanced filial generations in this cross may be useful in developing cucumber varieties with increased salinity tolerance. Alternatively, intermating of superior segregants may be explored to concentrate the favorable genes for salt tolerance. (C) 2013 Elsevier B.V. All rights reserved.