Measuring Maize Seedling Drought Response in Search of Tolerant Germplasm

Meghyn Meeks,Dirk Hays,Seth Murray,Steve Hague

doi:10.3390/agronomy3010135

Abstract

To identify and develop drought tolerant maize (Zea mays L.), high-throughput and cost-effective screening methods are needed. In dicot crops, measuring survival and recovery of seedlings has been successful in predicting drought tolerance but has not been reported in C4 grasses such as maize. Seedlings of sixty-two diverse maize inbred lines and their hybrid testcross progeny were evaluated for germination, survival and recovery after a series of drought cycles. Genotypic differences among inbred lines and hybrid testcrosses were best explained approximately 13 and 18 days after planting, respectively. Genotypic effects were significant and explained over 6% of experimental variance. Specifically three inbred lines had significant survival, and 14 hybrids had significant recovery. However, no significant correlation was observed between hybrids and inbreds (R2 = 0.03), indicating seedling stress response is more useful as a secondary screening parameter in hybrids than in inbred lines per se. Field yield data under full and limited irrigation indicated that seedling drought mechanisms were independent of drought responses at flowering in this study.

Highlights

Expanding populations with greater food and energy needs are increasing demand for greater global maize (Zea mays L.) production. Environmental limitations such as temperature and Agronomy 2013, 3 drought continue to restrain maize production levels as they have in earlier decades and in many areas this is predicted to worsen with changing climates [1,2,3]
This study demonstrates that maize seedling drought tolerance has enough obvious and significant quantitative genetic variation in diverse germplasm to allow statistical separation in means for both inbred lines and testcrossed hybrids
Maize breeders generally perform initial field selection on inbred lines based on important selected and transmitted phenotypes; these inbred lines are crossed to a tester genotype to evaluate their combining ability in hybrids and the best hybrid combinations will eventually be grown by farmers

Summary

Introduction

Expanding populations with greater food and energy needs are increasing demand for greater global maize (Zea mays L.) production. An initial focus solely on yield stability under time points of water stress has so far resulted in incremental progress [8] This has led to a search for secondary traits. In the case of maize these would ideally be identifiable in inbred lines and inherited to good yielding hybrids These traits include but are not limited to, shortened anthesis-silking interval (ASI) [9,10], delayed leaf senescence [9], increased rooting depth and density [11], hydraulic lift [12], high leaf number and short plant height [13], performance with limited available nitrogen [14], seedling vigor [15], and epicuticular wax [16,17]

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Conclusion