Field Based Assessment of Capsicum annuum Performance with Inoculation of Rhizobacterial Consortia

Comprehensive evaluation of fruit quality for premium Wangmo Castanea mollissima plants

In this study, the fruit phenotype and quality of 32 superior Wangmo Castanea mollissima plants (designated GM1 to GM32) were examined to identify the trait characteristics of different cluster groups and germplasms with excellent comprehensive performance. The goal was to provide a theoretical basis and research foundation for collecting high-quality germplasm resources and breeding superior cultivars of Wangmo C. mollissima. Ten fruit phenotypic traits and 13 quality traits were measured and analyzed in these 32 superior Wangmo C. mollissima plants. Cluster analysis and principal component analysis (PCA) were used to perform a comprehensive evaluation. Extremely significant positive correlations (P<0.01) were observed for 15 pairs of fruit phenotypic and quality traits, and significant positive correlations (P<0.05) were observed for 16 pairs of traits. Highly significant negative correlations (P<0.01) were observed for 4 pairs of fruit phenotypic and quality traits, and significant negative correlations (P<0.05) were observed for 15 pairs. The plants were divided into three groups by cluster analysis: the first group had large fruits and good fruit quality, the second group had small fruits and poor fruit quality, and the third group had medium-sized fruits with a high starch content. Four principal components were extracted from the 23 traits by PCA, contributing 76.23% of the variance. The ten plants with the highest comprehensive quality were GM32, GM31, GM29, GM1, GM8, GM17, GM10, GM30, GM3 and GM28. The results of this study provide a reference for the development and utilization of Wangmo C. mollissima germplasm resources.

Role of ACC-deaminase synthesizing Trichoderma harzianum and plant growth-promoting bacteria in reducing salt-stress in Ocimum sanctum

Salinity is a significant concern in crop production, causing severe losses in agricultural yields. Ocimum sanctum, also known as Holy Basil, is an important ancient medicinal plant used in the Indian traditional system of medicine. The present study explores the use of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase-producing strains of plant-growth-promoting bacteria (PGPB) namely Str-8 (Halomonas desiderata), Sd-6 (Brevibacterium halotolerans), Fd-2 (Achromobacter xylosoxidans), Art-7 (Burkholderia cepacia), and Ldr-2 (Bacillus subtilis), and T. harzianum (Th), possessing multi-functional properties like growth promotion, stress alleviation, and for enhancing O. sanctum yield under salt stress. The results showed that co-inoculation of Th and PGPBs enhanced plant height and fresh herb weight by 3.78-17.65% and 7.86-58.76%, respectively; highest being in Th + Fd-2 and Th + Art-7 compared to positive control plants. The doubly inoculated plants showed increased pigments, phenol, flavonoids, protein, sugar, relative water content, and nutrient uptake (Nitrogen and Phosphorous) as compared to monocultures and untreated positive control plants. In addition, co-inoculation in plants resulted in lower Na+, MDA, H2O2, CAT, APX activities, and also lower ACC accumulation (49.75 to 72.38% compared to non-treated salt- stressed plant) in O. sanctum, which probably played a significant role in minimizing the deleterious effects of salinity. Finally, multifactorial analysis showed that co-inoculation of Th and PGPBs improved O. sanctum growth, its physiological activities, and alleviated salt stress compared to single inoculated and positive control plants. These microbial consortia were evaluated for the first time on O. sanctum under salt stress. Therefore, the microbial consortia application could be employed to boost crop productivity in poor, marginalized and stressed agricultural fields.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01328-2.

Enhancing plant growth promoting rhizobacterial activities through consortium exposure: A review

Plant Growth Promoting Rhizobacteria (PGPR) has gained immense importance in the last decade due to its in-depth study and the role of the rhizosphere as an ecological unit in the biosphere. A putative PGPR is considered PGPR only when it may have a positive impact on the plant after inoculation. From the various pieces of literature, it has been found that these bacteria improve the growth of plants and their products through their plant growth-promoting activities. A microbial consortium has a positive effect on plant growth-promoting (PGP) activities evident by the literature. In the natural ecosystem, rhizobacteria interact synergistically and antagonistically with each other in the form of a consortium, but in a natural consortium, there are various oscillating environmental conditions that affect the potential mechanism of the consortium. For the sustainable development of our ecological environment, it is our utmost necessity to maintain the stability of the rhizobacterial consortium in fluctuating environmental conditions. In the last decade, various studies have been conducted to design synthetic rhizobacterial consortium that helps to integrate cross-feeding over microbial strains and reveal their social interactions. In this review, the authors have emphasized covering all the studies on designing synthetic rhizobacterial consortiums, their strategies, mechanism, and their application in the field of environmental ecology and biotechnology.

Plant-microbe-soil fertility interaction impacts performance of a Bacillus-containing bioproduct on bell pepper

Limited information is available on the performance of plant growth-promoting inoculants or bioproducts under different soil nutritional or fertility conditions. Consequently, the objective of this study was to evaluate the effects of a commercially available Bacillus-containing bioproduct, Microlife Abundance, at concentrations of 5.5 and 6.5 log cfu/ml on early growth, fertilizer use-efficiency, and fruit yield of bell pepper (Capsicum annuum L.) under two different soil fertility conditions (25% and 100% recommended N rates). Two pot experiments were conducted with bell pepper: (a) a 4-week-long early growth test with inoculant treatments applied once at transplanting; and (b) a 13-week-long yield test with inoculant treatments applied at transplanting and again at first blossom-set. Results from the early growth test indicated that at both N fertilization levels, applying Abundance once at transplanting at 6.5 log cfu/ml rather than 5.5 log cfu/ml significantly increased root dry weight, total root length, root volume, root surface area, and total length of very fine roots compared with the noninoculated control by 20%, 13%, 17%, 15%, and 12%, respectively. In contrast to the early growth, results from the yield test showed that only at the 100% recommended N rate, applying Abundance twice at both concentrations significantly enhanced N fertilizer use-efficiency and marketable yield of bell pepper over the noninoculated control by 34% (5.5 log cfu/ml) and 30% (6.5 log cfu/ml). Therefore, the efficacy of the Bacillus-containing bioproduct Abundance in enhancing fertilizer use-efficiency and marketable yield of bell pepper varied between soil nutritional conditions, but the early growth promotion effect of Abundance did not. Our results also demonstrate that selected microbial-based bioproducts, like Abundance, can be compatible with chemical fertilizers to enhance fertilizer use-efficiency and crop yields, but cannot be used as complete substitutes for chemical fertilizers.