Effect of VA-mycorrhiza inoculation on growth performance, coppicing ability and drought resistance of two agroforestry tree species

The better growth response of mycorrhizal plants was attributed to improvement in nutrient uptake, especially phosphorus, nitrogen and potassium and to better water status. VA-mycorrhiza inoculation subsequently produced more roots per plant, which were longer than the uninoculated control plants. Inoculation with vesicular-arbuscular mycorrhiza increased plant tissue phosphorus, nitrogen and potassium content, although the differences between mycorrhiza and control plants for nitrogen and potassium were not statistically significant. Overall, there was an increased in root colonization by the mycorrhiza fungi, and the percentage of colonization varied between the two plant species. The highest percentage colonization was recorded with Cassia spectabilis. VAM inoculation improved the coppicing ability of the two agroforestry tree species under well-watered and water stressed conditions. The mycorrhiza effect on coppice shoot biomass production in C. spectabilis was highly significant under both conditions, but the on effect Leucaena leucocephala was not. It was noted that under water stressed conditions the influence of mycorrhiza inoculation was more pronounced than under well-watered condition. The percentage coppice shoot biomass increment was higher under water stressed conditions than under well watered conditions. Although plant to plant variations obscured significant difference, VAM inoculation did tend to have greater drought resistance. Inoculated tree species not only had a higher shoot height, root collar diameter, above and below ground biomass production, but also a higher leaf water content, greater total root length and root biomass per plant than control plants. This resulted in higher root shoot ratios in inoculated plants. Due to higher biomass production in the inoculated than uninoculated plants, it took them fewer days to show signs of water stress