Selection Strategy for Sorghum Targeting Phosphorus‐limited Environments in West Africa: Analysis of Multi‐environment Experiments

Abstract

Although sorghum [Sorghum bicolor (L.) Moench] in West Africa (WA) is generally cultivated with limited or no fertilization on soils of low phosphorus availability, no assessments of the genetic variation among WA sorghum varieties for adaptation to low soil P are known. We assessed grain yields of 70 diverse sorghum genotypes under -P (no P fertilization) and +P conditions at two locations in Mali over 5 yr. Genetic variation for grain yield under -P conditions and the feasibility and necessity of sorghum varietal testing for grain yield under -P conditions were evaluated. Delayed heading dates (0-9.8 d) and reductions of grain yield (2-59%) and plant height (13-107 cm) were observed in -P relative to the +P trials. High estimates of genetic variance and broad-sense heritabilities were found for grain yield across both -P (^2 = 0.93) and +P (h^ = 0.92) environments. The genetic correlation for grain yield performance between -P and +P conditions was high (r^ = 0.89), suggesting that WA sorghum varieties generally possess good adaptation to low-P conditions. However, genotype x phosphorus crossover interaction was observed between some of the highest yielding genotypes from the -P and +P selected sets, with the variety IS 15401 showing specific adaptation to -P. Direct selection for grain yield in -P conditions was predicted to be 12% more efficient than indirect selection in +P conditions. Thus, selection under -P conditions should be useful for sorghum improvement in WA.

Integration of P acquisition efficiency, P utilization efficiency and low grain P concentrations into P-efficient rice genotypes for specific target environments

“…The latter strategy may be more realistic as different pathways or P uptakeenhancing mechanisms may benefit plant growth under low versus high P conditions, leading to different genotypes being superior in each environment. Such a crossover effect, whereby different genotypes were superior under low versus moderately P-deficient conditions, has earlier been described by Kirk et al (1998) and was recently observed for sorghum (Sorghum bicolor L. Moench) by Leiser et al (2012). Specific to rice, lowland and upland ecologies may require different plant strategies for efficient P acquisition.…”

Duplicate and Conquer: Multiple Homologs ofPHOSPHORUS-STARVATION TOLERANCE1Enhance Phosphorus Acquisition and Sorghum Performance on Low-Phosphorus Soils

“…In addition, because phosphate rock fertilizer is a nonrenewable resource that is being depleted by agricultural demands, increasing fertilizer prices negatively impact agriculture, particularly for small-holder farmers in developing countries in the tropics and subtropics (Cordell et al, 2009;Sattari et al, 2012). In sorghum (Sorghum bicolor), breeding strategies for low-P adaptation have been developed based on multienvironment trials in West Africa, indicating the importance of undertaking selection in low-P soil conditions (Leiser et al, 2012a(Leiser et al, , 2012b. Therefore, developing crops with greater ability to grow and maintain satisfactory yields on soils with reduced P availability is expected to substantially improve food security worldwide.…”

Plant Breeding: Past, Present and Future

“…Leiser et al (2012) assessed grain yields of 70 diverse sorghum genotypes under ÀP (no P fertilization) and +P conditions at two locations in Mali over 5 years. Leiser et al (2012) assessed grain yields of 70 diverse sorghum genotypes under ÀP (no P fertilization) and +P conditions at two locations in Mali over 5 years.…”