GENETIC DIVERSITY AND POPULATION STRUCTURE OF NAPIER GRASS (Pennisetum purpureum Schumach) IN WESTERN KENYA

Abstract

Napier grass (Pennisetum purpureum Schumach) is the dominant livestock fodder in all stall feeding systems in Kenya with other numerous applications. To date, no study in Kenya has been done on genetic diversity in napier grass that use both molecular and morphological markers. The objectives of this study was to determine genetic diversity and population structure of napier grass in western Kenya using simple sequence repeat (SSR) markers and morphological traits. A total of 96 samples out of 116 were studied using 25 selected SSR markers. The mean polymorphic loci index was 91.11% with the lowest being Alupe population at 85.19% while Busia and Butere at 94.44% each. Shannon information index ranged from 0.028 to 0.492 while Nei’s diversity index ranged from 0.021 to 0.329. Nei genetic distance ranged from -0.002 to 0.047 while identity ranged from 0.954 to 0.985. Most (90%) of the molecular variation in napier grass populations exists among individuals within populations, with lesser amount (1%) between populations. There was no distinct population structuring in the five populations studied. Morphological characterization showed moderate diversity with two major clusters and one minor cluster. This corroborated with molecular clustering data. The most important morphological characteristics for diversity study were; plant height, stool diameter, growth form, leaf length and tiller numbers. This study recommends increasing the level of diversity in the Western Kenya napier grass germplasm through introductions of new napier clones and proper selection so as to increase the chances of getting resistant genes to Napier Stunting Disease.