PLANT GROWTH PROMOTING POTENTIAL OF BANANA (MUSA SPP.) ENDOPHYTIC BACTERIAL IN KENYA

Abstract

In Kenya, banana production is constrained by among others, declining soil fertility. This is brought about by insufficient application of manure due to cost implications especially for the farmers without livestock, and limited use of inorganic fertilizers, which are expensive and therefore unaffordable for most banana farmers in Kenya.  A sustainable complementary approach would be to increase the biological inputs of nutrients by exploitation of microorganisms, which are largely untapped natural resources for plant growth promotion. Endophytes are diverse microbes, most commonly fungi and bacteria, which spend the entire or part of their life cycle living in internal plant tissues causing no apparent or immediate disease symptoms. Endophytes are of agronomic interest in that they can enhance plant growth in non-leguminous crops and improve their nutrition through nitrogen fixation, phosphate solubilization or iron chelation (siderophores production). This study was conducted with the aim of assessing functional potentialities of previously isolated and identified endophytic bacteria of bananas in Kenya in regard to their plant growth promoting potential that included abilities to fix free nitrogen, solubilize phosphates and produce siderophores. The 43 bacterial isolates used in this study belonged to the genera Serratia (17 isolates), Pseudomonas (12 isolates), Rahnella (4 isolates), Enterobacter (2 isolates), Raoultella (2 isolates), Yokenella (2 isolates), Bacillus (1 isolate), Klebsiella(1 isolate), Yersinia (1 isolate) and Ewingella (1 isolate). Siderophore production activity was detected with all the Pseudomonas isolates as determined on blue Chrome Azurol S (CAS) agar plates. Twenty seven isolates were observed to solubilize phosphates, with Rahnellaisolates showing the highest potential as determined on NBRIP growth medium. All the isolates grew on solid nitrogen-source free medium, suggesting their ability to fix nitrogen. In conclusion, endophytic bacteria of bananas in Kenya showed plant growth promoting potential, and in particular Rahnellaand Pseudomonas isolates.

Key words:     Musa spp., endophytic bacteria, diazotrophes, phosphate-solubilizing microorganisms, siderophores