The development of tolerant rice varieties using doubled-haploid technology is necessary to speed up the release of a variety tolerant to salinity stress. However, this requires a reliable screening method and selection index model for enhancing selection effectiveness. One approach is through the development of a selection index based on factor analysis under soil salinity screening in the greenhouse. The objective of this study was to develop a selection index model based on factor analysis and select tolerant doubled-haploid lines under high salinity conditions. The experimental design used was a split-plot design with salinity stress treatments as the main plot, i.e., normal (0 mM NaCl) and saline (25 mM NaCl ~ 5.6–5.8 dS/m) and 42 genotypes as the subplot. The genotypes consisted of 36 doubled-haploid lines, four commercial varieties, and two check varieties. The results indicated that a salinity selection index model involving yield and productive tiller traits could be used for selecting rice genotypes tolerant to salinity stress in soil artificial screening. This index which was developed through a combination of factor analysis, stress tolerance index (STI), and path analyses have identified 15 doubled haploid rice lines which were considered as good tolerant lines under salinity stress in soil artificial screening.

Improving the tolerance of crop species to abiotic stresses that limit plant growth and productivity is essential for mitigating the emerging problems of global warming. In this context, imaged data analysis represents an effective method in the 4.0 technology era, where this method has the non-destructive and recursive characterization of plant phenotypic traits as selection criteria. So, the plant breeders are helped in the development of adapted and climate-resilient crop varieties. Although image-based phenotyping has recently resulted in remarkable improvements for identifying the crop status under a range of growing conditions, the topic of its application for assessing the plant behavioral responses to abiotic stressors has not yet been extensively reviewed. For such a purpose, bibliometric analysis is an ideal analytical concept to analyze the evolution and interplay of image-based phenotyping to abiotic stresses by objectively reviewing the literature in light of existing database. Bibliometricy, a bibliometric analysis was applied using a systematic methodology which involved data mining, mining data improvement and analysis, and manuscript construction. The obtained results indicate that there are 554 documents related to image-based phenotyping to abiotic stress until 5 January 2023. All document showed the future development trends of image-based phenotyping will be mainly centered in the United States, European continent and China. The keywords analysis major focus to the application of 4.0 technology and machine learning in plant breeding, especially to create the tolerant variety under abiotic stresses. Drought and saline become an abiotic stress often using image-based phenotyping. Besides that, the rice, wheat and maize as the main commodities in this topic. In conclusion, the present work provides information on resolutive interactions in developing image-based phenotyping to abiotic stress, especially optimizing high-throughput sensors in image-based phenotyping for the future development.

Akbar MR, Purwoko BS, Dewi IS, Suwarno WB, Sugiyanta, Anshori MF. 2021. Agronomic and yield selection of doubled haploid lines of rainfed lowland rice in advanced yield trials. Biodiversitas 22: 3006-3012. Selection process is important step to obtain high yielding variety. This study aimed to obtain information on agronomic performance of doubled haploid lines of rainfed rice in advanced yield trials and select the best lines for multi-location yield trials. Two experiments were conducted in Bogor and Subang using a randomized complete block design for each location and consisted of 35 doubled haploid lines and two check varieties namely Ciherang and Inpari 18 as a treatment. The result revealed that interaction between genotype and environment (G x E) significantly affected all agronomic characters, except on the panicle length. Characters with high heritability value were all agronomic characters except number of productive tillers and productivity. Genotypic correlation analysis showed that number of productive tillers and weight of 1000 grains had significant and positive correlation with productivity. The selection used weighted selection index based on multivariate analysis. Fourteen lines were selected for multi-location yield trials. These lines had characteristics as follows: number of productive tillers (14.0-17.7 tillers), weight of 1000 grains (24.7-32.5 g), and productivity (5.0-6.2 ton ha-1). The selected lines can be evaluated further to obtain superior lines in multi-location trials.

The development of salinity tolerant varieties can be done by using doubled haploid technology. In the determination of the salinity tolerance trait, hydroponic screening at the seedling stage is the most common screening method. However, it needs improvement on the assignment of the tolerance traits. Cluster heatmap analysis has been reported to select lines by combining various data. The objective of the study was to select tolerant doubled-haploid rice lines to salinity stress at the seedling phase and evaluate the use of cluster heatmap analysis by combining tolerance score and growth characters. The study was conducted in a greenhouse using a nested factorial design (repetition nested in NaCl concentrations), with 3 replications. The plant materials used consisted of 62 genotypes and NaCl concentration levels consisted of 0 (1 dS/m) and 120 mM (13.3 dS/m). Hydroponic cultures used a Yoshida solution. Each container contained 14 experimental units and 2 units of check i.e. sensitive and tolerant controls. Observations was carried out on tolerance scoring and growth parameters. The results showed that tolerant and moderate genotypes have a lower pattern of decline than sensitive genotypes, especially in shoot-related characters. Based on the cluster heatmap analysis, there were 38 doubled haploid rice lines considered good tolerance traits under saline condition. The cluster heatmap assignment was considered more selective than only focused on tolerance score, especially in negative selection to sensitive lines.

Rice can absorb less than 40% of applied nitrogen fertilizer, whereas the unabsorbed nitrogen fertilizer may cause environmental problems, such as algal blooms in freshwater and increased production of nitrous oxide, a greenhouse gas which is 300 times more potent than carbon dioxide. Development of nitrogen use efficient (NUE) rice is essential for more environmentally friendly rice production. Recently, NUE rice has been developed by root-specific expression of alanine aminotransferase (AlaAT) gene from barley, a monocot plant. Therefore, we tested the efficacy of AlaAT gene from cucumber in transgenic rice, aiming to provide evidence for the conservation of AlaAT gene function in monocot and dicot. AlaAT gene from cucumber (CsAlaAT2) has been successfully cloned and constructed on pCAMBIA1300 plant expression vectors under the control of tissue-specific promoter OsAnt1. Agrobacterium tumefaciens-mediated transformation of Indonesian rice cv. Fatmawati using this construct produced 14 transgenic events. Pre-screening of T1 seedlings grown in the agar medium containing low nitrogen concentration identified selected events that were superior in the root dry weight. Southern hybridization confirmed the integration of T-DNA in the selected event genomes, each of them carried 1, 2, or 3 T-DNA insertions. Efficacy assay of three lead events in the greenhouse showed that in general transgenic events had increased biomass, tiller number, nitrogen content, and grain yield compared to WT. One event, i.e., FAM13, showed an increase in yield as much as 27.9% and higher plant biomass as much as 27.4% compared to WT under the low nitrogen condition. The lead events also showed higher absorption NUE, agronomical NUE, and grain NUE as compared to WT under the low nitrogen condition. The results of this study showed that root-specific expression of cucumber alanine aminotransferase2 gene improved nitrogen use efficiency in transgenic rice, which indicate the conservation of function of this gene in monocot and dicot.

Akbar MR, Purwoko BS, Dewi IS, Suwarno WB, Sugiyanta. 2019. Short Communication: Selection of doubled haploid lines of rainfed lowland rice in preliminary yield trial. Biodiversitas 20: 2796-2801. Yield trial is an important step in rice breeding program. This research was aimed at evaluating agronomic characters and selecting the best doubled haploid rainfed rice lines for next advanced yield trial. An experiment was conducted in Indramayu from March to August 2017. The research was arranged in randomized complete block design (RCBD) with three replications. Materials used were fifty-eight doubled haploid lines and two check varieties namely Ciherang and Inpari 18. The results revealed that all observed characters had broad genetic variability and high heritability. The number of productive tillers and the number of filled grains per panicle had a positive correlation and direct effect on productivity. Based on index selection, thirty lines were selected to have good agronomic characters and high yield. These lines had characteristics of plant height (85.7-124.7 cm), number of productive tillers (8.6-14.8 tillers), day to harvest (104.0-117.3 days), number of filled grains per panicle (136.7-264.7 grains), number of total grains per panicle (152.0-305.7 grains), weight of 1000 grain (21.5-31.3 g), and productivity (4.1-6.8 tons ha^-1). Keywords: good agronomic trait, high yield potential, selection index