Low Temperature–Tolerant Bradyrhizobium japonicum Strains Allowing Improved Soybean Yield in Short‐Season Areas

Abstract

In short‐season soybean [Glycine max (L.) Merr.] production areas, low soil temperature is potentially an important factor limiting soybean growth and yield. Some strains originating from cooler areas can cause more nodulation and nitrogenase activity under low‐temperature conditions. We have attempted to find Bradyrhizobium japonicum strains that can fix more N than strain 532 C under low‐temperature conditions. We selected 40 B. japonicum strains from the USDA collection based on their isolation from soils of northern locations. These 40 strains were tested for their ability to grow at a low (15°C) temperature, and the best two (USDA 30 and USDA 31) were selected for evaluation under field conditions. Inoculation with USDA 30 and USDA 31 resulted in greater soybean yields (an 8% increase, averaged over the 2 yr) than inoculation with 532 C. The increased yield was due to the formation of more pods per plant, and more seeds per plant, but not due to an increase in 100‐seed weight. This indicated that the benefit caused by the superior strains occurred early in plant development, probably due to increased N fixation early in the growing season. This possibility was supported by the observations that leaf areas, grain protein production, and total protein levels for plants inoculated with USDA 30 and USDA 31 were greater than those inoculated with 532 C. These findings clearly demonstrate that inoculant strains likely to perform best in a given geographical area are those selected for the conditions prevalent in the area.

Differential traits of rhizobia associated to root-nodules of gum acacia (Senegalia senegal), shittah tree (Vachellia seyal), pigeon pea (Cajanus cajan L) and cowpea (Vigna unguiculata)

“…Therefore, morphological, biochemical and symbiotic characterization on selective medium seem to be more adequate. Successful nodulation and N 2 fixation in the Legume-Rhizobium symbiosis require a close compatibility between the two partners and appropriate soil environment (Hirsch et al, 2003;Leibovitch et al, 2001;Zhang et al, 2002;Mishra et al, 2012). Although rhizobia from four crop legumes have been characterized and have shown efficiency in increasing the host plants yield in the Guinea-Savannah zone of Cameroon (Ngakou et al, 2009), nothing is known about the similarities/differences between rhizobia symbionts of food crop legumes and those of tree legumes such as acacia species.…”

Effects of biofertilizers on grain yield and protein content of two soybean (Glycine max L.) cultivars

“…P is an essential element for cell division, root development and seed formation (Gizawy and Mehasen, 2009). Similarly, Zhang et al (2002) reported that B. japonicum bacteria application increased the number of seed per plant of two soybean cultivars.…”

“…Olivera et al (2002) declared that the effect of combined inoculation of bean by phosphate solubilizing bacteria and Bradyrhizobium japonicum bacteria were positive on dry weight. Moreover, Zhang et al (2002) reported that B. japonicum bacteria increased number of pods per plant, number of seeds per plant, hundred seed weight, grain protein, total protein and development of plant leaves in two soybean cultivars. Kazemi et al (2005) also stated that soybean seed inoculation by rhizobial bacteria significantly increased the number of pods per plant, number of seeds per plant, thousand grain weights and finally the yield of soybean.…”

“…Kazemi et al (2005) reported that soybean seed inoculation with rhizobial bacteria significantly increased seed thousand weight. Zhang (2002) reported that inoculation with B. japonicum bacteria increased 100 seed weight of two soybean cultivars. Asadi Rahmani et al (2000) also observed that in the grain filling stage of soybean due to higher levels of photosynthesis in treatments inoculated with B. japonicum bacteria, more phosphate is transported to the grain and this factor could increase the size and weight of seed.…”

Preliminary characterization of slow growing rhizobial strains isolated from Retama monosperma (L.) Boiss. root nodules from Northwest coast of Algeria

“…Nodulation and N 2 fixation in symbiosis require that host and microorganism are compatible, but also that the soil environment be appropriate for the exchange of signals that precede infection (Hirsch et al, 2003;Leibovitch et al, 2001;Zhang et al, 2002). Furthermore, microbial communities are able to develop a range of activities that are very important in maintaining biological balance and sustainability in soil particularly under stress conditions Kennedy and Smith, 1995).…”