Comparison of Plant Growth Promoting Rhizobacteria (PGPR) Diversity and Dynamics During Growth of Cilembu Sweet Potato (Ipomoea batatas L var. Rancing) in Cilembu and Jatinangor Site, Indonesia

Validation and Evaluation of Plant Growth Promoting Potential of Rhizobacteria Towards Paddy Plants

This study aimed to characterize, validate, and evaluate the plant growth potential of bacterial isolates (E-2, T-2, and T-1) to determine their suitability for application as biofertilizers and/or plant-biostimulants. The plant growth-promoting potential of bacteria (E-2, T-2, and T-1) has been validated in a hydroponic study on paddy plants by inoculating bacterial isolates and monitoring the phenotypic and plant growth responses. The applicability of bacteria was tested based on their tolerance to salinity, susceptibility to antibiotics, and identification based on 16S rDNA sequencing. The isolates E-2, T-2, and T-1 improved plant growth variably and significantly (P < 0.05 at 95% confidence interval) when inoculated into the plant growth matrix, ensuring nutrient availability to the plants grown under a nutrient (nitrate or phosphate) deprived growth matrix. Isolates E-2, T-2, and T-1 grew at salt (NaCl) concentrations of 7%, 6%, and 6%, respectively, and were tolerant to saline conditions. Although these three isolates exhibited resistance to certain antibiotics, they were susceptible to a large number of readily available antibiotics. Isolates E-2, T-2, and T-1 were identified as Klebsiella sp. strain BAB-6433, Citrobacter freundii strain R2A5, and Citrobacter sp. DY1981 respectively, and all of these may be assigned to Risk-Group-2 and hence are safe in view of their susceptibility to readily available antibiotics. Hence, these isolates are promising for extensive evaluation as bioinoculants to ecologically improve soil quality, fertility, crop growth, and yield.

Yield stability analysis of orange - Fleshed sweet potato in Indonesia using AMMI and GGE biplot

Orange-Fleshed Sweet Potato (OFSP) is an important crop in Indonesia. Yield potential and genotypic adaptability are important factors in varietal development. The purpose of this study was to estimate the stability of yield and to select the best OFSP genotypes across three agroecosystems in West Java, Indonesia. The field trials used were augmented design with 50 F1 Orange-Fleshed Sweet Potato (OFSP) genotypes as treatment, and seven check varieties as controls. The experiments were conducted in three different agroecosystems in West Java (Sumedang, Bandung, and Karawang). Selection was based on physical characteristics of sweet potato tuber, yield and stability across three environments. Data analysis of the yield characters, yield component, and tuber quality were performed by combined variance analysis. Selected genotypes were analyzed for stability yield using the parametric, non-parametric, Additive Main effects and Multiplicative Interaction (AMMI), AMMI Stability Value (ASV), and Genotype and Genotype by Environment (GGE) biplot models. Results identified the top best ten F1 genotypes namely F1-38 (G1), F1-69 (G2), F1-71 (G3), F1-77 (G4), F1-127 (G5), F1-128 (G6), F1-135 (G7), F1-159 (G8), F1-191 (G9), and F1-226 (G10). Location showed a significant effect on yield. Genotypes F1-069, F1-077, F1-226, F1-038, and F1-128 have the lowest ASR based on non-parametric and parametric stability models and there were identified as the most stable. AMMI analysis identified F1-128, F1-135, F1-038, and F1-069 as the most stable genotypes. F1-38 (G1), F1-69 (G2), F1-128 (G6) were found to be the most stable genotypes based on ASV analysis, while GGE biplot identified F1-38 (G1) and F1-69 (G2) genotypes as the stable genotypes. Other genotypes were considered to as location-specific. Based on AMMI, ASV, and GGE Biplot models, F1-038, and F1-069 were identified as stable genotypes. They produced higher yields than other genotypes. Therefore, the F1-038 and F1-069 genotypes can be potentially recommended as superior varieties for West Java, Indonesia.

GC/MS-based metabolic profiling for the evaluation of solid state fermentation to improve quality of Arabica coffee beans

INTRODUCTION

Coffee fermentation has been reported as one key process in aroma and flavor development of coffee. However, natural fermentation often results in inconsistent quality of coffee. In this study, second fermentation using isolates from feces of civet (Luwak) and Cilembu sweet potato were used to improve the quality of Arabica green coffee beans.

OBJECTIVES

The aim of this research was to improve the quality of various Arabica coffee from different origins in Indonesia by controlled-second fermentation.

METHOD

The Arabica coffee beans used in this study were from three origins in Indonesia: Kintamani-Bali (I), Aceh-Gayo (II) and Nagarawangi-Sumedang (III). The second fermentation was done using three bacterial isolates coded as BF5C(2); UciSp14; and AF7E which belong to Bacillus genus. Quality assessment of fermented coffee was performed by cupping test following Specialty Coffee Association of America (SCAA) protocol by licensed Q graders, GC/MS metabolite profiling, and total polyphenol content measurement.

RESULTS

The controlled-second fermentation for 4-8 h was successful to increase total polyphenol content well as to improve the complexity of coffee taste and coffee quality (cupping score > 84). Comparative GC/MS analysis showed that fermentation of coffee beans resulted in alteration of metabolite profiles of coffee beans compared with control, while still maintaining the characteristics of coffee based on each origin.

CONCLUSION

The controlled-second fermentation was effective to increase the quality of coffee and alter metabolite composition of coffee that were associated with changes in taste profile of coffee. This report may serve as basis for producing coffee with better taste quality with higher polyphenols content through standardized fermentation production in industrial scale.