Characterization of some upland rice (Oryza sativa L.) genotypes under low phosphorus condition
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Date
2018-07
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AAU, Jorhat
Abstract
The investigation was carried out for characterization of some upland rice
(Oryza sativa L.) genotypes under low phosphorus condition during Jan 2017 to May
2018 in the Stress Physiology Laboratory, Department of Crop Physiology, Assam
Agricultural University, Jorhat-13. The main objective of the investigation was to
evaluate upland rice cultivars adapted under to low phosphorus condition and to
identify the physiological traits contributing to rice growth and development under
low phosphorus condition. The study was done to understand the mechanism of
phosphorus altering the physiology of rice crop, and its relationship between yield,
physiological attributes and nutrient status of rice as influenced by Phosphorus.
In first experiment, fifty rice accessions of different genetic backgrounds
were used for the evaluation of low-P tolerance. The accessions were grown in two
sets of plastic pots; oneset was treated with – P and another with +P using Hoagland
solution. Treatment was imposed at 5 days interval. The potential accessions were
screened out under the above simulated level of P for studying tolerant ability of the
lines using SES scoring. On the basis of SES scoring eight line viz. Kasalth, Ronga
Ahu, Amo Amkel, Maipholong, Sesapal, Bizary, Bijor and Haringajali were identified
as tolerant to low P.We made an attempt to study, the mechanism of tolerance to low
P which was elucidated in second experiment. In the second experiment, the seed of
screened lines were grown in the three sets of plastic pot, maintaining the soil with
zero “0” level of P (normal soil), second at 10kg/ha of P (moderate dose) and third
was maintained at 20kg ha-1 (recommended doses of P).
Results obtained during the investigation revealed that P significantly
influenced various morpho-physiological, biochemical and yield parameters.A
significantly variable response was observed in genotypes due to different levels of P.
Due to low P, stress induced reductionin terms of root length, root biomass, shoot dry
weight, plant height, specific leaf weight, number of tillers per hill, no. of leaves per
hill, and photosynthetic parameters were lower in Maipholong and at par with
Kasalath (check line). However, Ronga Ahu and Amo Amkel also showed the similar
trend compared to check line under low level of P. A reduction in values of relative
membrane stability index and Chlorophyll Stability Index, proline content were
recorded under „0‟ dose of P. Under low and moderate P level, a comparatively better
performance was recorded in Maipholong and Kasalath in terms of yield and yield
related parameter viz. panicle length, number of filled grain and grain yield. The
tolerance indices parameter viz. P use efficiency and P uptake revealed that cultivar
Maipholong and Kasalath showed maximum in all doses of P followed by Ronga Ahu
and Amo Amkel. The susceptible lines invariably reflected less favourable plant P
utilization, more metabolic de-arrangements in terms of photosynthesis rate, nitrate
reductase activity and depression level of membrane stability.
From the results of the experiment it might be concluded that Maipholong
and Kasalath was more suitable under low P condition indicating that lines are
adaptable to low phosphorus by maintaining better root growth, photosynthesis,
chlorophyll stability index, NR activity and NPK level within the plant.