TITLE:
Screening of Rice Accessions for Tolerance to Drought and Salt Stress Using Morphological and Physiological Parameters
AUTHORS:
Chukwudi Umego, Valentine Otang Ntui, Effiom Eyo Ita, Charles Opara, Edak Aniedi Uyoh
KEYWORDS:
Oryza sativa, Salinity Tolerance, Drought Tolerance, Morpho-Physiological Parameters, Stress Response Indices
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.11 No.12,
December
24,
2020
ABSTRACT: Drought and salinity are the most widespread soil problems,
posing a big threat to food security in rice growing regions. The present study
evaluated the performance of eleven rice genotypes using morphological and physiological
parameters, under induced drought and salinity conditions. The seedlings were raised
in 5 kg of homogenous soil in plastic bags in the greenhouse. For the drought experiment,
each bag was watered with 200 ml of water twice daily until plants reached the five-leaf
stage when watering was suspended for 2 weeks for the drought stressed plants but
not suspended for the control plants. The experiment was a 2 × 11 factorial and
the set up was arranged using the completely randomized design with three replications.
Data were taken on Plant height, Number of tillers, leaf length, Number of green
leaves, Number of dead leaves, Leaf rolling score (LRS) and Rate of water loss.
The salinity experiment was set up in a similar manner except that the plants were
irrigated twice a day for 2 weeks with 200 ml of treatment solution containing either
0 mM NaCl or 75 mM and data were collected on plant height, number of tillers, shoot
fresh weight, shoot dry weight, Na+ and K+ concentrations,
relative water content and chlorophyll content. Data from both experiments were
subjected to Analysis of variance test using the GenStat software 10th edition and the means separated using least significant difference test. Individual
stress response index (ISRI) was calculated for each parameter and the means used
in grouping the varieties. Of the genotypes evaluated, four (FARO 44, NERICA 2,
NERICA 8 and NERICA 5) were identified as tolerant, two (NERICA 4 and FARO 57) as
moderately tolerant, while the rest were found to be sensitive to drought. Equally,
two varieties (FARO 44 and RAM 137) stood out in the salinity screening as tolerant
varieties, five were moderately tolerant while four (FARO 64, FARO 52, NERICA 2
and FARO 55) were clearly susceptible. FARO 44 is the only genotype that showed tolerance to both drought and salinity. The
identified drought and salinity tolerant rice genotypes from this study can be recommended
as genetic sources for future breeding programs for drought and salinity tolerance in rice.