Effects of Different Types of Sand and Vermiculite Grades on the Test Tube Method for Evaluating Preinoculated Seed1

Abstract

Combinations of two types of sand and two grades of vermiculite in test tubes (25 × 200 mm) were evaluated for growth of seedlings with root nodules at 21 days of age. Rhizobium‐inoculated alfalfa seeds were planted two per test tube. Each type of sand was suitable for testing provided it was washed free of fine particles. Seedlings grown in substrate combinations which included the vermiculite having smaller (0.32 cm) particle sizes produced fewer nodules regardless of the sand type.