Maize water content and solute potential at three stages of development.

Abstract

Maize (Zea mays L.) productivity is highly sensitive to water stress at flowering but selection for water stress tolerance might be performed more efficiently during vegetative growth To test the consistency of rank for relative water content (RWC) and solute potential (Ψ s ) at different stages of development 15 S 4 and 2 inbred maize lines were sampled for midday RWC determined by a modified method (mRWC) and solute potential normalized to 100% mRWC (Ψ s100 = Ψ s X mRWC/ 100) at vegetative flowering and kernel development Both mRWC and Ψ s100 varied significantly among genotypes Midday mRWC was significantly correlated between vegetative and flowering (r = 0.72 ** . P = 0.01) but not between vegetative and kernel development or flowering and kernel development stages However there was no significant correlation of Ψ s100 among vegetative flowering and kernel development stages. Date of anthesis was used as an index of maturity and was significantly correlated with mRWC and Ψ s100 at certain stages (mRWC: vegetative r = 0.27 * , kernel development r = -0.50 ** and Ψ s100 : vegetative r = -0.30 * flowering r = 0.39 ** , kernel development r = 0.54 ** ). In a related experiment 48 S 4 and four inbred lines were sampled for change in RWC (ΔmR-WC) and change in Ψ s100 (ΔΨ s100 ) by detached leaves of field-grown plants The ΔΨ s100 and ΔmRWC varied significantly among lines Date of anthesis was correlated with ΔmRWC (r = -0.19 * ) but not Ψ s100 We conclude that the rank of maize genotypes for mRWC and ΔΨ s100 may be affected by the degree of development and selection should be performed on plants sampled at equivalent maturities.