ESTIMATING VARIABILITY, HERITABILITY, AND GENETIC ADVANCE OF RICE GENOTYPES IN MID-HILLS OF NEPAL

Rice is an essential staple food in Nepal but researches and varietal improvement programs are rarely carried out due to inadequate variability study. The field study was carried to diagnose the influence of genetic and environmental factors on yield traits to aid future rice breeding programs. Twelve genotypes were arranged in randomized complete block design with three replications from July to November 2019 at the research field of the Institute of Agriculture and Animal Science, Tribhuvan University, in the hilly area of Nepal. Analysis of variance showed significant difference for days to 50% booting, days to 50% flowering, plant height, panicle length, flag leaf area, filled grains per panicle, unfilled grains per panicle, fertility percentage, effective tillers m-2, straw yield, grain yield, 1000-grain weight, and harvesting index indicating the presence of variation in genotypes. LPN BR-1615 was the most promising genotype in grain yield. The values of Phenotypic Coefficient of Variation (PCV) were higher than Genotypic Coefficient of Variation (GCV) for each trait and low difference between them was found for days to 50% booting, days to 50% flowering, plant height, panicle length, grain yield, thousand-grain weight, fertility percentage, and harvesting index. Plant height, effective tillers m-2, and grain yield showed high heritability (i.e. 93.2%, 60.5% and 92.6%, respectively) and higher genetic advance as percentage of mean (i.e. 46.5, 34.6 and 50.1, respectively) . Thus, the experiment revealed that selections favoring plant height, effective tillers m-2, and grain yield would help in effective breeding programs of rice in future

EFFECT OF SCREEN HOUSE MODIFICATION AT FLOWER BUD STADIA ON FLOWER QUALITY OF CHRYSANTHEMUM AT MEDIUM UPLAND ELEVATION

Higher temperature and light intensity at the medium upland elevation decrease the number of blooming flowers, flower diameter, and red color flower intensity of Chrysanthemum morifoliumcompared to that at the high upland elevation. The environmental modification was needed during the flower development phase to improve the quality of chrysantheum at a medium upland elevation. The study aimed to find the suitable screen house environmental modification for increasing the chrysanthemum quality at the medium upland elevation. The study consisted of two factors. First, environmental modification of a screen house, such as (1) control, (2) the addition of shading net on the rooftop of the screen house, (3) the addition of a misting system in the screen house, and (4) the addition of a combination of shading net on the rooftop and misting system in the screen house. Second, the chrysanthemum varieties, including (1) Yastayuki (white flower), (2) Arosuka Pelangi (yellow flower), and (3) Socakawani (red flower). Experiments were arranged in a completely randomized design with three replications. Data were analyzed by combined ANOVA. The results showed that either the addition of a shading net or misting system reduced the number of flower buds growing. The competition among flower buds was found to be reduced by decreasing the number of flower buds.  Consequently, the number and diameter of the blooming flower increased. The addition of a shading net on top of the screen house was the most suitable environmental modification to increase the chrysanthemum quality at the medium upland elevation

SSR MARKERS REVEALED GENETIC DIVERGENCE OF RICE BROWN PLANTHOPPER POPULATIONS MAINTAINED ON TWO SETS OF DIFFERENTIAL HOST VARIETIES

Resistance screening of promising rice lines in Indonesia requires the use of brown planthopper (BPH) biotypes 1, 2, and 3. Three BPH populations have been raised as biotypes 1, 2, and 3 on differential rice host of improved varieties Pelita I-1 (no Bph gene), IR26 (Bph1), and IR42 (bph2), respectively. Three alternative populations have also been developed on the respective traditional varieties TN1 (no Bph gene), Mudgo (Bph1), and ASD7 (bph2). Although these populations displayed two virulent patterns other than biotype 1 to 3 phenotypes, they were expected to be discriminated into two virulence groups by SSR analysis. The study aimed to investigate the level of genetic variation among the six BPH populations using SSR markers and to relate it with the observed virulence patterns. Genotyping of 30 females with 29 polymorphic SSR markers revealed higher genetic parameter values in populations reared on improved varieties than those on traditional varieties. This difference was marked as two population clusters in PCoA plots corresponding to the host variety type, in contrast to the previous assumption that clustering would be based on virulence patterns. The presence of individuals with unwanted virulence allele, either resulting from contamination during the long period of rearing or lack of host adaptation period, is suspected. The result of this study indicates that the six populations are not suitable for resistance screening. Virulence selection must be performed until they attain biotype 1 to 3 phenotypes which can be genetically separated by DNA markers

GIBBERELLIC ACID PRIMING ENHANCES MAIZE SEED GERMINATION UNDER LOW WATER POTENTIAL

Germination is a portentous yield determining factor that is a challenge in the low water potential environment due to disrupted imbibition. Hormonal seed priming can markedly increase the germination on maize even in such a stressful environment. Therefore, research was aimed to analyze the application of gibberellic acid (GA3) priming to maize seeds to minimize the deleterious effects of reduced water potential. GA3 priming was done at 0, 50, 100, 150, and 200 ppm for 12 hours and subjected to drought levels of 0, 0.15, 0.50, 1.05, and 1.75 MPa by using NaCl solution. Different germination parameters, i.e., germination percentage, mean germination time, germination index, relative water content, seedling vigor index, root length, and shoot length, were determined on the final day of the experiment. The results showed that all germination parameters were adversely influenced by low water potential. Every level of GA3 priming has hastened all parameters. GA3 priming at 100 ppm decreased the mean germination time by 35 hours under 1.75 MPa compared to non-primed seeds. GA3 priming increased the shoot length of maize seedlings with a shoot length of 2.9 cm in non-primed seedlings compared to 6.4 cm in 200 ppm GA3 priming under 1.05 MPa. GA3 priming is the best method for the early establishment of maize seedlings in low water potential conditions. As a result, it may be utilized as a low-cost and straightforward approach for establishing maize crops under saline and drought conditions

POTENTIAL OF ENDOPHYTIC FUNGI DERIVING FROM ASIATIC PENNYWORTH TO PRODUCE ANTIOXIDANTS

Asiatic pennyworth is a medicinal plant that contains triterpenoids, saponin, flavonoids, and tannins which possess antioxidants. Endophytic fungi from the plant could produce a similar compound; therefore, antioxidants could be made in the laboratory if the fungi are isolated. This study aimed to evaluate the potential of endophytic fungi isolated from Asiatic pennyworth to produce antioxidants. The study used 34 endophytic fungal isolates from Asiatic pennyworth accessions of Malaysia (17 isolates) and Bengkulu, Indonesia (17 isolates) collected by the Indonesian Center for Agricultural Biotechnology and Genetic Resources Research and Development. The fungi were propagated in a potato dextrose broth medium, then mycelia mats and filtrates were separated and then freeze-dried. The antioxidant activities were first tested with 1,1-diphenyl-2- picrylhydrazyl (DPPH) using thin layer chromatography (TLC), then UV-Vis spectrophotometry λ517 nm with five variations of concentration. Results showed all 34 fungal isolates have antioxidant activities based on a yellowish-white color change after applying 0.002% DPPH solution of the TLC method and IC50 value of the UV-Vis spectrophotometer. The highest antioxidant activity was shown by Aspergillus austroafricanus MB 1 (IC50 = 12.08 ppm) from Bengkulu accession and A. oryzae MM 13 (IC50 = 10.29 ppm) from Malaysia accession. A. austroafricanus MB 1 produced more antioxidant compounds (seven) than A. oryzae MM 13 (six). The antioxidant compounds produced by both endophytic fungi included in the group of flavonoids, fatty acids, and carboxylic acids. The research implies that A. austroafricanus MB 1 and A. oryzae MM 13 could be further developed as sources of antioxidants

RESISTANT LEVEL OF SOYBEAN GERMPLASM AGAINST POD SUCKING BUGS (Riptortus spp.)

Increasing productivity of soybean has often been constrained by pod sucking bugs (Riptortus spp.) which caused a serious damage  and yield losses up to 80%. Breeding for obtaining soybean variety resistant to pod suckers needs the availability of soybean germplasm resistant to the pest. The study aimed to obtain a candidate for soybean variety resistant to Riptortus spp. through the selection of 100 accessions of soybean. The study included the preparation of test plants and test insects, pest infestations, observations, and looking for a practical screening method for pod sucking pests. The experiment used a completely randomized design for two treatments (infested and non-infested Riptortus spp.). Cikuray variety and PI-092734 accession were used as a control. Results showed that there was a very low correlation among variables observed. Twelve soybean accessions showed a resistance to Riptortus spp., i.e. C7301-113AC-POP, Lokal Madiun-3549, Lokal Klungkung, ML.2974, Singgalang, Lokal Jepara, Lokal Jatim, Lokal Trenggalek, Lokal Tulungagung, Lokal Tabanan, Lokal Blitar, and Lokal Kuningan 10. These accessions were more resistant than the popular released variety such as Wilis, Grobogan, Detam 2, and Gepak Ijo. Small seed size was not a major determinant of soybean resistance to pod suckers. The addition of observational components, i.e. probing preference and oviposition, indicated that crop damage was indirectly influenced by the high frequency of probing and oviposition, although its relation to plant tolerant mechanisms still needs further investigation. Indeterminate plant types require further validation as to whether they contribute significantly to plant resistance against pod sucking insects

CRITICAL VARIABLES OF MORPHO-PHYSIOLOGICAL RICE PLANT UNDER STAGNANT FLOODING CONDITIONS

Stagnant flooding (SF) stress has contributed decreasing rice production in Indonesia. The study aimed to explore critical variables of rice growth that contribute to the decreasing grain yield under SF conditions and a common irrigation system (control). The experiment was arranged in a complete randomized block design with four replications to test 10 rice genotypes (Inpari 30 Ciherang Sub-1, Inpara 3, Inpara 4, Inpara 8, IRRI119, IRRI154, IR42, IR14D121, IR14D157, and Tapus). The water depth was managed according to the farmer’s practices for control, while for SF plots the standing water depth was gradually increased from 35 days after transplanting and was maintained at 50 cm until harvest. Results showed that plant height, tillering ability, leaf greenness, panicle number per hill and grain filling percentage were critical growth variables that affect grain yield at optimal conditions. The yield of the 10 genotypes decreased by 25–50% under SF conditions. Inpara 3 had the stable yield in those two watering conditions. Therefore, it could be used as a check variety for SF condition. Inpara 9 and IRRI119 experienced decreased yield of more than 50% under SF conditions. The key factors determining the decreased yield were tillering ability and green leaf level. Optimization of the two variables at SF conditions will largely determine rice yield associated with panicle number per hill and grain number per panicle. Results of the study are useful as preliminary recommendations for designing new variety and cultivation techniques to reduce the impact of SF stress on rice yield

EFFECT OF AMELIORANT ON GROWTH AND YIELD OF RICE AT TIDAL PADDY FIELD

Rice (Oryza sativa L.) is the most important and strategic food crop in Indonesia, but low productivity in tidal paddy fields is a serious problem that must be overcome. The application of ameliorant would be worthy to increase the growth and yield of rice in tidal paddy fields. The study aimed to investigate the effect of ameliorant application on growth and yield of rice varieties in tidal paddy fields. The study was arranged in a split plot design with five replications. Rice varieties tested were Inpari 34, Dendang, Inpara 9, Inpari 35, and Ciherang as the main plot, and ameliorant types studied were humic acid, gypsum, zeolite, and organic fertilizer as the subplot. The results showed that the use of different rice varieties and amelioran types significantly increased the growth and yield of rice. Inpara 9 produced 7.6 t.ha-1 dry milled grain (DMG) or increased by 33.3% compared to Ciherang variety. Humic acid application at 25 kg ha-1 increased grain yield by 21.3% higher than that without ameliorant treatment. The best treatment to increase the growth and yield of rice in tidal paddy field was a combination of humic acid 25 kg.ha-1 and Inpari 34 which produced the DMG of 8.6 t ha-1 or 41% higher compared to Ciherang without ameliorant

IDENTIFICATION OF IRON TOLERANT CANDIDATE LOCI IN RICE DETERMINED THROUGH GENOME-WIDE ASSOCIATION STUDY

Iron (Fe) toxicity is a significant abiotic stress in swamp land. The study aimed to identify the candidate loci related to Fe toxicity tolerance through Genome-Wide Association Study (GWAS) approach.  The study used 288 rice accessions consisting of 192 breeding lines and 50 local landraces, and custom-designed 384 rice SNPs-chips. A field evaluation was conducted in inland swamp for two season periods (2014 and 2015). Phenotypic data and association mapping were analyzed using XLSTAT and TASSEL 3.0. The candidate loci were analyzed by functional gene detection of the significant SNPs aligned to the Rice Annotation Project and the Institute for Genomic Research databases. Three linkage disequilibrium (LD) blocks were detected in the Fe tolerant population around the significant SNPs. The first LD block was mapped in chromosome 1 (the AtIRT gene and qFETOX1; qFETOX1-3 QTLs loci) resembled partitioning of Fe-toxicity tolerant mechanism. The second LD blocks located in chromosome 2 (qFE-TOX-2-1 and qFETOX-2 QTLs loci) and chromosome 3 (qFETOX-3 QTL, OsNAS1 and OsNAS2 loci), probably contributed to Fe exclusion mechanism. The third LD blocks located in chromosome 4 (OsFRO2 and qFETOX-4 QTL loci) and chromosome 7 (OsIRT2 and NAS3 loci). The third LD block found on tolerant genotypes both on vegetative and generative stages. This condition indicated that these loci were presumed playing a role for Fe toxicity tolerance in rice. Result of the study are beneficial for determining the strategy on developing Fe-toxicity tolerant rice for specific swamp land type through breeding programs

USING GLOBAL CLIMATE INDICES TO PREDICT RAINFALL AND SUGARCANE PRODUCTIVITY IN DRYLANDS OF BANYUWANGI, EAST JAVA, INDONESIA

In Indonesia, sugarcane (Saccharum officinarum L.) is mostly cultivated in drylands, thus depending on rainfall for crop growth and development. Rainfall is an essential factor affecting sugarcane productivity. The global climate indices can be used to investigate potential of rainfall within a given area and its relationship with crop productivity. This reserach aimed to analyze the relationship between the global climate index, rainfall, and sugarcane productivity in drylands near Glenmore sugar mill, i.e., Benculuk and Jolondoro, Banyuwangi, East Java, Indonesia. The global climate index data used were the Southern Oscillation Index (SOI) and Sea Surface Temperature (SST) between 1995 and 2014. Results of this research showed that SOI and SST can be used to predict the rainfall in both Benculuk and Jolondoro. Rainfall (y) can be predicted with SST data (x) using the equation of y = -352.49x + 7724.1 in Benculuk and y = -107.32 + 3443.4 in Jolondoro, as well as with SOI data (x) using the equation of y = 38.664x + 1555.1 in Benculuk and y = 10.541x + 1567.8 in Jolondoro. Sugarcane productivity (y) in Jolondoro can be predicted using data of total rainfall (x) between October and March with the following equation: y = -0.1672x + 1157.3. This equation can be used by sugar mills, sugarcane growers, and other sugarcane-relevant stakeholders for determining the appropriate growing season