The development of rice seedlings stressed by drought and salt is shown by different morphometric and colorimetric traits. These distinctions can be used to understand the response of plants to challenging conditions. Therefore, this study aimed to assess the efficacy of image-based phenotyping in the early testing of rice plants and observe how the plants respond to both drought and salinity. A stress tolerance index with multivariate analysis was used for the selection of the most important traits. The experiment consisted of 2 factors, namely the degree of environmental stress and rice genotype. Furthermore, the degree of environmental stress comprised normal (NaCl and PEG 0%), drought (10% PEG), salinity (60 mM NaCl), as well as a combination of moderate drought and salinity (5% PEG + 30 mM NaCl). The results showed that both morphometric (area, convex hull, bounding area, perimeter, centermassy) and colorimetric (CIVE, VARI, RGBVI, MGRVI, NDI, GLI, NGRDI) can be used as selection characters.
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To determine the lethal dose (LD) and growth-reducing dose (GR), the exposures were from gamma activity rates such as low activity rate by multipurpose panoramic 70 Ci and high activity rate by Gamma Cell 3 kCi. The study material was sourced by Cobalt-60 (60Co) with variant doses, i.e., 10Gy, 20Gy, 30Gy, 40Gy, 50Gy, and 60Gy for each gamma activity rate. The study was performed at the Center for Isotope and Radiation Application, National Nuclear Energy Agency of Indonesia (CIRA-NNEA). Data were analyzed using non-parametric tests and analysis of variance. The lethal dose (LD50) and growth reduction (GR50) were identified based on regression analysis. The analysis of variance revealed that highly significant differences among irradiation treatments in number of leaves, survival rate, and plant height. A linear regression model was developed to determine the mean LD50 and GR50 of Super Napier grass. The highest variability of mutants was observed in gamma-ray irradiated mutants with lethal doses (LD50). LD50, 35.82Gy-55.71Gy, at a low activity rate (Multipurpose panoramic irradiator 70 Ci) is higher than the high activity rate (Gamma Cell 3 kCi), 28.98-28.99. In general, the survival rate of Super Napier grass decreased along with increasing irradiation dose. The generated LD50 and GR50 were identified as optimal dosages for the radiosensitivity of Super Napier grass. This study becomes preliminary mutagenesis breeding to generate genetic diversity of grass, specifically in Super Napier grass.
One of approaches to maintain the yield stability of the lowland tropical wheat is the use of secondary traits in the selection process. The identification of these characters requires a statistical approach in the form of genetic parameter analysis and multivariate analysis. The
objective
of this study was to determine the secondary traits of adaptive wheat mutants in the lowlands through the use of genetic parameters and multivariate analysis on the parameters. The study consisted of three field trials conducted in three different regencies, namely Jeneponto (135 m above sea level (asl)), Maros (100 m asl) and Bantaeng (125 m asl). The study used a nested design, where replications were nested in the environments. The genotype factors consisted of 20 genotypes repeated three times. 11 characters were observed including vegetative and reproductive characters. The analysis used consisted of repeatability, correlation, cluster analysis, principal component analysis, factor analysis, and cross print analysis. The overall results of the analysis indicate that the number of productive tillers is the main secondary trait for the selection of adaptive wheat in the lowlands. The character can be recommended for selection criteria in testing wheat lines in the lowlands to make an effective selection.
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