Root and leaf anatomy of water stressed upland rice (Oryza spp.) cultivars in response to compost and arbuscular mycorrhizal fungus augmentation

Occurrences of drought impair the functional efficiency of plant internal tissues responsible for mineral uptake and assimilate transportation, resulting in poor growth and yield reduction. The response of internal tissues of root and leaf of upland rice to drought in soil amended with compost and arbuscular mycorrhizal fungi (Glomus deserticola), AMF, has not been properly studied. We examined the effects of water deficit on tissues of root and leaf of Oryza species in soil amended with compost and AMF. The treatments consisted of three rice cultivars: IR-64, NERICA-4 and CG-14 sown in pots filled with 6 kg sandy loam soil amended separately with AMF, compost and unamended (control). The trial was laid out in a completely randomised design with six replicates. The plants were water-stressed by imposing drought at 25% field capacity for 7 days each at tillering, panicle and grain filling stages. After drought imposition, plants were harvested and thin transverse sections (15 mu) of root and leaf samples were obtained. The specimens were stained and placed on glass slides covered with slips for observation and photomicrographs under a compound microscope. Water stress caused proliferation of vascular bundles and increased the number of airspaces and root hairs in all the rice cultivars. Epidermal and sclerenchyma cells were thickened in stressed plants grown in pots amended with compost. There was an unusual increased number of vascular tissues with copious sclereids, interspersed with aerenchyma and dense root hairs in NERICA-4. Generally, NERICA-4 cultivar appeared more tolerant to drought than CG-14, while IR-64 was highly susceptible to water limiting conditions. Root and leaf tissue of upland rice showed characteristics of drought tolerance when grown on water deficit soils augmented with compost as compared to G. deserticola amended soil, or soil without amendment.