Effect of seed size, colour, number of seeds per hill and depth of planting on sorghum seed survival and stand establishment: relationship to phytophagous insects

Abstract

Sorghum, Sorghum bicolor (L.) Moench, seeds were planted in two different cropping systems, 'casado' (sorghum and maize in the same hill) and 'golpe alterno' (sorghum and maize in alternating hills) in one test; and in monocolture in a second test to determine the effects of number of sorghum seeds hill-1 and depth of planting, and seed size and colour, respectively, on seed survival and stand establishment in an area in Central Honduras infested with seed and seedling insect pests. Seed size and colour did not influence the amount of damage to seeds and seedlings by insect pests. More seeds were destroyed or removed where seeds were planted 7 .5 cm deep than at 2.5 cm. Seedling emergence was higher when seeds were planted 2.5 cm deep than at 7.5 cm. Seeds were damaged less by insects, and seedling emergence was higher in the alternate hill system than in the same hill system. The loss of seeds and reduction in plant stand was due mainly to ants (Solenopsis geminata (F.)), although white grubs (Phyllophaga sp.) and fall armyworms (Spodoptera frugiperda (J. E. Smith)) contributed to stand destruction.