Seedling Growth Responses of Oat Genotypes1

Abstract

The objectives of these investigations was to utilize a seedling growth technique to (i) verify previous reports on growth responses of germinating seedlings to nutrient additives; (ii) determine how soon seedling growth sponses occur; (iii) measure differences in genotypic respouses.A preliminary test with two F2 oat populations (Arena sativa L.) and their respective parents (‘Firecracker’ and ‘Goodand’; Goodland and N.C. 55) verified earlier observations of increased shoot growth and reduced root growth by 10‐lay‐old seedlings grown with a modified halfstrength Hoagland's solution, as compared to a growth medium of distilled water. Parental means were different and within‐parent variability was exhibited.Shoot and root lengths and dry weights, plus root volume, were measured on 4‐ to 10‐lay‐old seedlings of four oat genotypes (‘Carolee’, ‘Salem’, N.C. 2469‐3, and Firecracker) grown in distilled water and in modified half‐strength Hoagland's solution. Responses to the nutrient solution were apparent for shoot length and weight, and generally occurred after 6 to 8 days, depending upon the genotype. Hoagland's solution resulted in increased shoot length and shoot weight but reduced root length. Root weight and volume did not respond to the nutrient solution.Genotypic differences were evident for all five characters. The dwarf llne, N.C. 2469‐3, developed both shoots and roots more slowly than any of the other genotypes. Firecracker developed shoots and roots most rapidly while Carolee and Salem developed them at intermediate rates. Genotype ✕ growth medium interactions were evident for shoot length and weight and for root volume. A method for determination of root volume using the displacement technique is presented.