Agriculture Reference
In-Depth Information
CHAPTER 7
EVALUATION OF BIOFERTILIZERS IN
IRRIGATED RICE: EFFECTS ON GRAIN
YIELD AT DIFFERENT FERTILIZER
RATE
NI
Ñ
O PAUL MEYNARD BANAYO, POMPE C. STA. CRUZ,
EDNA A. AGUILAR, RODRIGO B. BADAYOS,
AND
STEPHAN M. HAEFELE
7.1 INTRODUCTION
Biofertilizers are becoming increasingly popular in many countries and
for many crops. They are defined as products containing active or latent
strains of soil microorganisms, either bacteria alone or in combination with
algae or fungi that increase the plant availability and uptake of mineral nu-
trients [1]. In general, they contain free-living organisms associated with
root surfaces but they may also include endophytes, microorganisms that
are able to colonize the intercellular or even intracellular spaces of plant
tissues without causing apparent damage to the host plant. The concept of
biofertilizers was developed based on the observation that these microor-
ganisms can have a beneficial effect on plant and crop growth (e.g., [2]).
Consequently, a range of plant growth-promoting rhizobacteria (PGPR)
has been identified and well characterized. Direct beneficial effects can
occur when the microorganisms provide the plants with useful products.
The best known case of this are microorganisms that can directly obtain N
