| dc.description.abstract | Drought is a major challenge for all agricultural crops, but for rice, it is even more serious,
becauseof its semi aquatic phylogenetic origins and the diversity of rice ecosystems and growing
conditions. The most important source of climate-related risks for rice production in rainfed
areasis drought. Crop physiology has made a significant contribution to understanding the
mechanisms underlying crop growth and development, and bridging the "phenotype gap"
generated by the recent progress in genomics. Some studies involving plant water status and
photosynthesis in upland or lowland have been recorded , but a thorough analysis of below and
aboveground plant biomass in relation to genetic (G) ,environment (E) and management (M) is
stilllacking. Large genotypic variations have been found for roots in upland rice; however,
quantitative comparisons between the deep root morphology of rice cultivars on upland fields
and the effects of soil water conditions and nutrient load upon it are still limited. This study
assumesthat the genotypic characteristics required for drought resistance would be determined
as affected by site-specific, soil properties and fertilizer management, and that the assessment of
G x E x M interaction is necessary requirement for enhancing and stabilizing the upland rice
productivity under drought-prone environments. The study aimed to determine growth and
physiologicalresponse of selected upland rice genotypes (IRAT 109, Lemont and NERICA 4) to
waterdeficit, fertilizer application and in different soil types. This study was carried out in the
University Botanic Garden, Maseno during September 2011 to January 2012. Plants were
subjectedto water nutrient stress treatment in the field and in PVC tubes. Two experiments were
conducted, field trial (Exp. 1) and PVC-tubes trial (Exp. 2). Experiment 1 had three fertilizer
treatments, (N, P, and NP) and a control and only Nand NP for experiment 2. Experiment 1
and2 had, 2 and 3 genotypes respectively with 2-water managements, in a split-plot design. Exp.
2 had two-soils-type in Randomized Completely Blocked Design (RCBD). Water treatment
startedat 42 das in Exp. 1 and 35 das in Exp. 2., fertilizer treatment, was applied at 60 Kgha-1N,
and 60 Kgha·IN + 45 Kgha-1p, at 42 and 56 das; in Exp. 2, 80 Kgha-1N, 60 Kgha-\ P and 80
Kgha-1N+ 60 Kgha-1p, was applied in fertilized tubes, at 21 and 42 das. Shoots measurements at
21,42,63 and 84thdas, roots sampling at the same interval at depths of 0-10 em, 10-20 em, and
20-40Cm. the parameters measured included. soil moisture content, growth parameters, plant
biomass, N content, stomatal conductance and yields. The parameters measured recorded a
similartrend in the field and in the PVC tubes. The soil moisture content had significant effect
and decreased with increasing water deficit. The growth parameters like plant height, plant
biomass both shoot and root reduced with decreasing water content and nutrient load in the soil.
The water stressed plant, Lemont, registered the lowest growth parameters. Lemont, being the
most water stressed plant had the lower stomatal conductance and N content. The yield
component declined in water stressed conditions, IRAT 109 had the highest yield while Lemont
the least. Results indicates that under water-nutrient deficit, IRAT 109 has a superior
physiological traits such as high stomatal conductance and high N foliar content hence can be
recommended for growing under rainfed conditions in Kenya. This finding will ultimately help in
poverty eradication through increased income and improved food security. | en_US |
