Effect of Steeping Duration and Inoculum Concentration on Growth Promotion of Seedlings of Food Crops Primed in Cultures of Bacillus spp from Rhizosphere

Seed priming represents a viable, low-cost approach to improving germination and plant growth. This study aimed to assess the effects of steeping duration and inoculum concentration of seed crops on germinability enhancement of seed primed in cultures of Bacillus species from rhizospheres. The seeds used were cowpea (Vigna unguiculata), soya bean (Glycine max), sorghum (Sorghum bicolor), sesame (Sesamum indicum), and okra (Abelmoschus esculentus).

A total of five Bacillus species (four species of B. cereus and one species of B. thuringiensis) were used for priming the seeds. For the effect of steeping duration on germinability, viable surface-sterilized seeds were primed in growth broth cultures of the respective isolates. Every one hour, for a five-hour duration, a known number of seeds were withdrawn from the cultures and sown. In the case of initial inoculum, seeds were steeped in different dilutions of the bacterial cultures at the optimal steeping duration obtained in the first study before planting. At the expiration of planting duration, final germination percentage, germination time, germination index, and seedling vigor index of the respective seeds were estimated.

The results highlight the importance of steeping duration for seeds such as cowpea and soybean, and the effect of inoculum concentration was less drastic than that of steeping duration.

Further field studies need to be carried out to validate these results, using results here as baseline data.