Rice (Oryza sativa) farming is the largest single use of land for producing food. India is the largest rice growing country and 2nd in terms of production. Rice belongs to the genus Oryza of the family Gramineae and forms the staple food of 2.7 billion people. Various abiotic stresses limit rice production in acidic soil environments. Among these various abiotic stresses Iron (Fe) and Aluminium (Al) toxicity affect the rice production under low and upland conditions respectively.
The present study was conducted on a set of promising genotypes, their F1s, and a set of NILs (Near isogenic Lines) to determine the combining ability of parents adapted to acidic soil conditions through L x T analysis and also for evaluation of parents and NILs under acidic soil, aluminium and iron toxic hydroponics conditions. A relationship between seedling stage aluminium and iron toxicity tolerance under hydroponics condition and field performance under acidic soil was also made in this study.
In the genetic analysis, among the lines, L1 and L5 (Priya and Sahbhagi Dhan), while among the testers T1 and T3 (IR 24 and Kasalath) showed the best general combining ability while the crosses Sahbhagi Dhan X Kasalath (L5 X T3), Shahsarang X Sambamasuri (L4 X T2), Priya X IR 24 (L1 X T1) showed the best specific combining ability. Also, Sahbhagi Dhan X Kasalath (L5 X T3) showed maximum heterosis for seven of the ten traits studied when compared to the best commercial cultivar of the region, Shahsarang.
Field level screening of NILs in acidic soil was done in augmented design along with three checks Swarna, Shahsarang, Sahbhagi Dhan. Based on nine different traits superior, average and inferior performing lines were selected.
By means of hydroponic experiment conducted using Magnavaca’s nutrient solution (for Al toxicity screening) and Yoshida‘s solution (for iron toxicity screening), different superior and inferior lines were identified based on parameters like root growth, root/shoot biomass. It may however be mentioned that there were no significant correlation between superior and inferior lines in field and hydroponics but some lines were identified which perform well in both condition and perform poor in field as well as hydroponics condition.
The information generated would help identify suitable parents for breeding programme under acidic soils and the phenotypic data on the NILs may serve as a base for future mapping of loci responsible for yield under acidic soils, aluminium and iron toxic conditions.