| Abstrakt: |
The area of crop cultivation can be increased by selecting suitable genetic resources adapted for the relevant selection pressure. The areas with sandy soil and extremely higher temperature, used for crop cultivation, create problems of groundwater contamination due to the extensive and frequent application of Nitrogen (N) fertilizer combined with heavy irrigation. The tolerant chili varieties for the reduced N supplements are a potential solution to overcome the aforementioned problems. Thirteen commercial chili varieties were assessed in vitro in three NH4NO3 levels (656.25, 437.5, 218.75 mg/L) representing 75, 50 and 25% of the full strength (100%) of 875 mg/L, using 60 seedlings per each level in a duplicate experiment. The parameters of the number of leaves and roots, length of roots and shoots, dry weight of shoots and roots and chlorophyll content were recorded. The Stress Susceptibility Index (SSI) was calculated. The data were analyzed using the statistical tools of Analysis of Variance (ANOVA), Tukey test, Response Surface Analysis (RSA), Principle Component Analysis (PCA), Coefficient Correlation analysis and Hierarchical Cluster Analysis. The N content in the biomass of selected varieties at different tolerant categories was analyzed. ANOVA indicated a significant decline in the growth and development of some varieties under the reduced N while others showed comparable performance to the control at different N levels. The parameters including the number of leaves and roots, length of shoots, dry weight of shoots and roots and total dry weight contributed mainly to the tolerance to reduced N whereas, the length of roots, chlorophyll content and root-to-shoot ratio had a minimal contribution which showed a lower correlation with the highly contributed parameters. Based on the cluster analysis using SSI, Vijaya F1, Lanka Hot, Devnur Deluxe and Kodian were identified as the tolerant varieties and Ragini as a highly susceptible variety. Other varieties fell in between the two extremes. The accuracy of the categorization was confirmed by the N assay with comparable N at each level in tolerant varieties and a significant drop in susceptible varieties where a genotypes-dependent absorption efficiency was demonstrated. The study clearly revealed the feasibility of using the in vitro technique as an efficient method for identifying the N-tolerant varieties. Key message: The seedlings at early developmental stage are suitable for screening the tolerance to stress condition simulated by reduced nitrogen levels under in vitro. Adaptation was done by enhancing the absorption by increasing the number of roots. [ABSTRACT FROM AUTHOR] |
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