Growing Season and Location Effects on Water Uptake and Drying Rates of Peanut Seeds from Genotypes Resistant and Susceptible to Invasion by Aspergillus flavus Lk. ex. Fr.1,2

Abstract

AbstractAs a means to detect differences in testae properties between peanut (Arachis hypogaea L.) seeds from genotypes resistant to invasion by A. flavus Lk. ex Fr. and seeds from genotypes susceptible to the fungus, the water uptake and drying characteristics of the seeds were compared. Testae properties that could aid in control of A. flavus invasion of peanut seeds and the effect of growing conditions on these properties were sought.Seeds of both genotypes were grown in Puerto Rico in 1972 and Puerto Rico and Texas in 1973. Growing season and location significantly affected rate and total water uptake of cured seeds. With or without testae, the rate and total water uptake were greater for seeds grown in Puerto Rico than those grown in Texas. When growing conditions produced seeds with comparatively high water uptake capabilities (Puerto Rico), intact seeds of ‘Florunner’ and the genotypes resistant to invasion by A. flavus had slower water uptake rates than genotypes more susceptible to mold invasion. The data suggest that there are functional differences, indicative of structural differences, between testae of resistant and susceptible genotypes. When growing conditions produced seeds with comparatively low water uptake capabilities (Texas), there was less distinction between resistant and susceptible genotypes (based on water uptake patterns). However, one susceptible genotype retained a higher rate and total water uptake than all other genotypes. These data indicate that growing conditions affected testae structure that regulates the rate of water uptake by the seeds.Seed drying tests showed that Florunner and genotypes resistant to A. flavus invasion dried to moisture levels (10% or less) unfavorable for A. flavus growth at rates significantly faster than the susceptible genotypes. Drying patterns were unaffected by growing location.Lipid and protein contents of the seeds were not correlated with water uptake characteristics, although they varied with growing season and location.Slow rates of water uptake and the rapid drying rates of seeds of the resistant genotypes are attributes favorable to control of A. flavus invasion. If these attributes, along with resistance to A. flavus invasion, could be genetically transferred to other peanut genotypes, it is likely that contamination of peanuts by A. flavus could be reduced.