Phosphorous Efficiency and Tolerance Traits for Selection of Sorghum for Performance in Phosphorous-Limited Environments

Sorghum (Sorghum bicolor (L.) Moench) is widely cultivated in West Africa (WA) on soils with low phosphorus (P) availability. Large genetic variation for grain yield (GY) under low-P conditions was observed among WA sorghum genotypes, but information is lacking on the usefulness of P-tolerance ratios (relative performance in –P [no P fertilizer] vs. +P [with P fertilizer] conditions) and measures of P-acquisition and internal P-use efficiency as selection criteria for enhancing GY under low-P conditions. We evaluated 70 WA sorghum genotypes for GY performance under −P and +P conditions for 5 yr in two locations in Mali and assessed P acquisition (e.g., P content in biomass) and P-use efficiency (e.g., grain produced per unit P uptake) traits under −P and +P conditions in one site in 2010. Significant genetic variation existed for all P-tolerance ratios across multiple sites. Photoperiod-sensitive landrace genotypes showed significantly better P tolerance and less delay of heading under P-limited conditions compared with photoperiod-insensitive varieties. Genotypic correlations of P-tolerance ratios to GY under −P were moderate. Phosphorous acquisition and P-use efficiency traits independent of harvest index were of similar importance for GY under −P conditions in statistically independent trials. However grain-P and stover-P concentrations from one −P trial showed only weak correlations with GYs in statistically independent trials. Highest predicted gains for −P GY were obtained by theoretical index selection based on −P GY combined with P-use efficiency traits (e.g., low-grain P concentration). Such index selection is expected to achieve both increased sorghum productivity and P sustainability in the P-limited WA production systems. W.L. Leiser, State Plant Breeding Institute, Univ. of Hohenheim, 70593 Stuttgart, Germany; H.F.W. Rattunde and E. Weltzien, International Crops Research Institute for the Semi-Arid Tropics, BP 320 Bamako, Mali; H.P. Piepho, Institute of Crop Science, Bioinformatics Unit, Univ. of Hohenheim, 70593 Stuttgart, Germany; A. Diallo and A. Toure, L’Institut d’Economie Rurale, Bamako, Mali; B.I.G. Haussmann, Institute of Plant Breeding, Seed Science and Population Genetics, Univ. of Hohenheim, 70593 Stuttgart, Germany. Received 27 May 2014. Accepted 18 Dec. 2014. *Corresponding author ([email protected]). Abbreviations: +P, with P fertilization; −P, without P fertilization; BLUP, best linear unbiased prediction; BMY, total biomass yield; GCV, genetic coefficient of variation; GY, grain yield; GYR, grainyield ratio; h2, broad sense heritability; HDR, heading-date ratio; ICPOES, inductive-coupled plasma optical-emission spectrometer; PBM, P content of total biomass; PCG, P concentration in grain; PCS, P concentration in stover; PG, grain P content; PHI, P harvest index; PHR, plant-height ratio; PS, P content of stover; PUTIL-BM, P utilization for biomass production; PUTIL-G-Hi, P utilization for grain production adjusted for harvest index; PUTIL-G, P utilization for grain production; PUTIL-S, P utilization for stover production; SVR, seedling-vigor ratio; SY, stover yield; WA, West Africa. Published in Crop Sci. 55:1–11 (2015). doi: 10.2135/cropsci2014.05.0392 Freely available online through the author-supported open-access option. © Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.