Effect of plant growth-promoting rhizobacterial composite culture on the growth of chickpea seedlings

In the present study, 20 soil and plant samples from 13 villages of Raipur, Durg, and Balod District of Chhattisgarh (India) were collected from chickpea fields. From these samples, a total of 86 isolates including 16 Rhizobium, 40 Azotobacter, 29 Azosprillum, and one PSB were obtained on selective culture media. All the isolates were screened for their plant growth-promoting traits. Three (GmR8, ASL3 & ASL4) out of 86 were finally selected for further studies. One Azotobacter isolate, i.e., Azo137, was selected from the departmental culture collection. Finally, four isolates including GmR8 (Rhizobium), ASL3, ASL4 (Azospirillum), and Azo137 were selected for composite culture formulations. GmR and ASL4 were siderophore-producing isolates, whereas ASL3 and Azo137 were IAA producer along with their ability to fix nitrogen. Five composite cultures were prepared randomly and tested for effect on the growth of chickpea (the seedling test and the pot experiment). Among all the composite culture groups, C2 (GmR8, Azo137, ASL4) significantly increased the root (10.84 cm) and shoot (8.10 cm) length, whereas biomass (3.60 g) was the highest in the case of C1 (GmR8, Azo137, ASL3, ASL4) of seedlings as compared to the control (6.80 cm, 2.60 cm, and 3.30 g, respectively). Overall, the study revealed a better performance of composite or mixed culture over individual bacteria.

Efficiencies of Clonally Replicated and Seedling Testing for Spruce Breeding and Deployment Strategies

Genetic gains based on a genetic test using clonal replicates were compared to those based on a test using seedlings at the same gene diversity and testing effort levels using POPSIM™ Simulator. Three testing and deployment strategies targeting for white spruce (P. glauca [Moench] Voss) and black spruce (P. mariana (Mill.) B.S.P.) in New Brunswick were compared: seedling test with clonal seed orchard deployed as seedlings (CSO_ST), clonally replicated test with clonal seed orchard deployed as seedlings (CSO_CRT), and clonally replicated test deployed as a clone mix (MVF). The breeding populations (BP) were formed by balanced within-family selection and the production populations (PP) were selected by strong restriction on relatedness, i.e., no parent in common. Compared to the seedling test, the clonally replicated test resulted in faster accumulation of additive effects but quicker loss of additive variance in the BP, and this is particular true in the case of lower narrow-sense heritability or less non-additive genetic variance. The quicker loss in BP additive variance was overcompensated for by its faster accumulation in BP additive effect, resulting in higher gain in the clonally replicated test based PPs. Compared to the CSO_ST, the gain superiority of the CSO_CRT increased with generations, decreasing narrow-sense heritability or reducing the amount of non-additive variance. Implementing MVF was the most effective in terms of gain in most simulated cases and its superiority over the CSO_ST increased with generations, decreasing narrowsense heritability, or increasing non-additive genetic variance. Overall results demonstrated significant advantages of using clonally replicated test both for BP advancement and PP selection in most of the scenarios, suggesting that clonally replicated test should be incorporated into current spruce breeding strategies.