Choice of Harvest Method for Maximizing Seed Yield and Effect of Storage Methods on Seed Quality of a Panicum maximum (Local Type) in Southern Benin (West Africa)

Abstract

The aim of this study was to assess the effect of different harvesting methods on the seed yield of a Panicum maximum ecotype and to identify the storage method that maximizes seeds viability and vigour. Six methods of seed harvesting were assessed in a randomized complete block design with for replications: Seed heads shaken every 3 days into a large seed net receptacle (Shake); Seed heads covered with a nylon net bag, with an outlet to collect the seed (Cover); A nylon net receptacle placed under the seed heads for 3 weeks after 50% seed head emergence (Under); Seed heads cut 15, 20 and 25 days after 50% seed head emergence (Cut 15, Cut 20 and Cut 25 respectively). The seed storage methods were applied based on the best three seed-harvesting methods that yielded high seed yields. The storage methods included storing in gunny bags with cow dung ash as the seed treatment (SM1), seed treatment using Mortein Doom®, a modern seed protectant (SM2) and cow dung ash (SM3); in both cases seeds were stored in airtight containers. Quality analysis of the seeds was done first before storage and then after three and six months of storage. Data were analyzed through ANOVA. After 3 years of cultivation, highest seed yields were obtained from Cover and Under in all years and these treatments also gave the highest seed quality. Of mechanical harvesting methods, Cut 20 gave the highest seed yields, but required a high level of precision in determining optimum harvest date. Early harvesting resulted in immature, low quality seed, whereas when harvesting was delayed, a high proportion of seed had already been shed. The results of seed storage indicate that the method SM1 had the poorest performance. Seeds of this storage method have significantly lower vigour after three and six months’ storage and recorded significantly higher insect damage. They had significantly higher moisture content increase. The best treatment was storage in airtight containers with either Mortein Doom® or cow dung ash as the seed treatment. Cow dung ash should therefore be combined with air tight storage to increase the seed longevity