Response of intercropped barley and fenugreek to mono- and co-inoculation with Sinorhizobium meliloti F42 and Variovorax paradoxus F310 under contrasting agroclimatic regions.

In the present research, we aimed to select efficient rhizobia and plant growth-promoting rhizobacteria (PGPR) from fenugreek nodules and assess their performance as bio-inoculum for intercropped fenugreek and barley. Inoculation effects with selected bacteria were investigated firstly on fenugreek plants under greenhouse experiment and secondly on intercropped fenugreek and barley under three different agro-environmental conditions for two consecutive years. Sinorhizobium meliloti F42 was selected due to its ability to nodulate fenugreek and effectively improve plant growth. Among non-nodulating endophytic bacteria, Variovorax paradoxus F310 strain was selected regarding its plant growth-promoting traits showed in vitro and confirmed in vivo under greenhouse experiment. Field inoculation trials revealed a significant improvement in fenugreek nodulation (up to + 97%) as well as in soil enzymes activities (up to + 209%), shoot N content (up to + 18%), shoot dry weight (up to + 40%), photosynthetic assimilation (up to + 34%) and chlorophyll content of both intercropped plants in response to the mono-inoculation with Sinorhizobium meliloti F42, compared to the un-inoculated treatment at the SBR and JBS sites. Variovorax paradoxus F310 inoculation significantly increased shoot P content of both intercropped plants at the three experimental sites compared to the un-inoculated treatment (up to + 48%). It was shown that bacterial inoculation was more efficient at the low-rainfall region than the high-rainfall region. The co-inoculation with Sinorhizobium meliloti F42 and Variovorax paradoxus F310 resulted in a significant reduction in fenugreek nodulation and shoot N content. This survey showed the benefits of rhizobial and PGPR inoculation as efficient bio-inoculums to promote the cereal-legume intercropping system and highlights the influence of site-specific environmental factors on Rhizobium-PGPR-plant interactions.

Zinc fortification as a tool for improving sprout hygienic and nutritional quality: a factorial design approach.

BACKGROUND: Sprouting is known to improve cereal and pulse nutritional properties. However, several outbreaks of illness have been reported after raw sprout consumption. This research aimed to improve wheat sprout hygienic properties through the use of zinc diacetate. Sprouting conditions (sprouting temperature, soaking time and zinc diacetate solution concentration) were optimized to decrease total plate count, coliforms, and molds and yeasts using a factorial design approach and a desirability function. RESULTS: Based on the responses, the effects of variables were calculated and the interactions between them were determined. Optimal conditions were defined as follows: sprouting temperature 18 °C, soaking time 0.66 h and zinc diacetate concentration 400 mg L-1 . These conditions led to the elimination of coliforms and a decrease in total flora count by 2 log. Interestingly, zinc sprouting increased the zinc content of sprouts and improved their nutritional properties. CONCLUSION: Results showed that the use of zinc solution is a useful tool to improve sprout hygienic and nutritional properties. © 2019 Society of Chemical Industry.