Variation in cereals from the Himalayas and the optimum strategy for sampling plant germplasm.
Abstract
Seed samples of wheat and barley were collected in Nepal and Pakistan, from c. 100 villages in each country. Nepal is said to be a Vavilovian 'centre of diversity' for barley and Pakistan for wheat. The samples were grown in controlled conditions in Bangor, N. Wales. The means, between-plant variances and CV for all characters, apart from awn length, were remarkably similar when comparisons were made both within and between the spp. of the 2 regions. Since the variation outside the previously defined centres of diversity was similar to that within them, the concept of centres of diversity must be reconsidered. The barley collected from the rain-fed agriculture of Nepal was more disease resistant than the barley collected from the irrigated agriculture of Pakistan. It is likely that wheat from Nepal is more disease resistant than wheat from Pakistan. It was concluded that there seems to be little advantage in collecting plant germplasm from within centres of diversity in an attempt to capture the max. amount of genetic variation. Collections should be made as widely as possible, and cover areas of great ecological (climatic and edaphic) or cultural variation. The max. amount of variation for disease resistance is likely to occur in areas where the incidence of disease is greatest.