Anthony O. Adesemoye

Improvement of Crop Protection and Yield in Hostile Agroecological Conditions with PGPR-Based Biofertilizer Formulations

Intensive research attempts are underway to mitigate the impacts of climate change, improve salt tolerance and disease resistance of plants using organic farming practices, including biofertilizer which eventually improve degraded soils. In addition, it will form part of integrated environmentally friendly approach for nutrient management and sustainability in ecosystem functions. The use of such microbial inoculants as biofertilizers or biopesticides portends a great promise for controlling disease, improving plant health and soil productivity under environmentally stressed conditions. Stress-tolerant microorganisms with plant-stimulating properties are being discovered, selected and tested under field conditions and the number of successful applications is increasing. Formulation of microorganisms with various carrier materials enables long-term storage and protects them from various stress factors. This review summarizes the current status of microbial inoculants usage and prospects in crop cultivation and crop stress management, with particular attention to arid stress agro-ecological conditions.

Microbial Inoculants for Optimized Plant Nutrient Use in Integrated Pest and Input Management Systems

The use of fertilizers and pesticides has greatly increased agricultural productivity over the past few decades. However, there is still an ongoing search for additional or alternate tools that can proffer agricultural sustainability and meet the needs of profitability and greater food production for the growing world population. This review examines the enhancement of plant nutrient use efficiency derived from interactions of the diverse microorganisms that live in and around plants such as plant growth-promoting rhizobacteria (PGPR) and mycorrhizal fungi. These microorganisms form the major bases of the biorational sector of the agriculture industry which has exploded in the last few years with the production of many new microbial inoculant products and the improvement of existing products. Microbial inoculants cannot replace chemical fertilizers now or in the immediate future; thus this review discusses the concept of integrated pest and input management (IPIM), compatibility of inoculants with existing chemicals, and efficacy issues associated with biologicals. Also discussed are inoculant products, the conditions that may affect their success, the untapped potentials for agriculture, and the possible impacts on greenhouse gas emissions and global warming.

Evaluation of Bacillus Strains for Plant Growth Promotion and Predictability of Efficacy by In Vitro Physiological Traits

Bacilli are commonly used as plant growth-promoting agents but can be limited in effectiveness to certain crop and soil environments. The objectives of this study were to (1) identify Bacillus strains that can be consistent in promoting the growth of corn, wheat, and soybean and (2) determine whether physiological traits expressed in vitro can be predictive of growth promotion efficacy/consistency and be used for selecting effective strains. Twelve Bacillus strains isolated from wheat rhizospheres were evaluated in greenhouse pot tests with nonsterile soil for their effects on the growth of corn, soybean, and wheat. The strains also were assessed in vitro for multiple physiological traits. All 12 strains increased corn growth significantly compared to the controls. The four most efficacious strains on corn—Bacillus megaterium R181, B. safensis R173, B. simplex R180, and Paenibacillus graminis R200—also increased the growth of soybean and wheat. No set of traits was a predictor of growth promotion efficacy. The number of traits expressed by a strain also was not an indicator of efficacy as strain R200 that was positive for only one trait showed high growth promotion efficacy. Effective strains can be identified through pot tests on multiple crop plants, but in vitro physiological assays are unreliable for strain selection.

Bot Canker Pathogens Could Complicate the Management of Phytophthora Black Pod of Cocoa

Black pod is a major hindrance to cocoa production in Nigeria. It is caused by three different Phytophthora species with Phytophthora megakarya as the most important species in Nigeria and West African sub-region. Phytophthora spp. may enhance infections by opportunistic pathogens such as members of the Botryosphaeriacea that cause branch and trunk cankers in many woody plants across the world. Botryosphaeriacea has not been reported in cocoa nor in any woody plants in Nigeria to our knowledge. In the cocoa belt of Nigeria, research and understanding on cocoa black pod and Phytophthora is limited partly because of delayed or no access to some culture media, including required antibiotics. The objectives of this study were to: (1) use locally available materials to develop media for Phytophthora isolation from infected cocoa trees and pods samples and (2) to determine if members of Botryosphaeriaceae are associated with cankers of cocoa trees infected with black pod in Ondo State. The two formulated media, clarified tomato juice agar and cocoa pod agar supported the growth of Phytophthora spp. and were used for isolation from five cocoa producing local government areas, spanning all three senatorial districts of Ondo State. Based on morphological characteristics, four different species of Botryosphaeriaceae were identified from infected cocoa trees/pods but also from citrus and kola trees, which are similar to cocoa and usually planted in the same orchard with cocoa in Nigeria. These findings of new pathogens in cocoa and other hosts in Ondo State indicated the need for new strategies in the management of cocoa diseases in the State and across cocoa producing areas of Nigeria. n n Key words: Cocoa, Canker, Black pod, pathogens, Botryosphaeriaceae, Phytophthora.