| Biochemistry |
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| Differential response of root morphology to potassium deficient stress among rice genotypes varying in potassium efficiency |
| Yan-bo JIA, Xiao-e YANG, Ying FENG, Ghulam JILANI |
| MOE Key Laboratory of Polluted Environments Remediation and Ecosystem Health, Zhejiang University, Hangzhou 310029, China; Institute Calibration and Testing for Quality and Technical Supervision, Hangzhou Bureau of Quality and Technical Supervision, Hangzhou 310004, China; Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition, Zhejiang University, Hangzhou 310029, China; Department of Soil Sciences, Arid Agriculture University, Rawalpindi 46300, Pakistan |
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Abstract Disparity in the root morphology of six rice (Oryza sativa L.) genotypes varying in potassium (K) efficiency was studied with three K levels: 5 mg/L (low), 10 mg/L (moderate) and 40 mg/L (adequate) in hydroponic culture. Morphological parameters included root length, surface area, volume and count of lateral roots, as well as fine (diameter<0.2 mm) and thick (diameter>0.2 mm) roots. The results indicate that the root growth of all genotypes was reduced under low K, but moderate K deficiency increased the root length of the efficient genotypes. At deficient and moderate K levels, all the efficient rice genotypes developed more fine roots (diameter<0.2 mm) than the inefficient ones. Both fine root count and root surface area were found to be the best parameters to portray K stress in rice. In accordance with the root morphology, higher K concentrations were noted in shoots of the efficient genotypes when grown at moderate and deficient K levels, indicating that root morphology parameters are involved in root uptake for K and in the translocation of K up to shoots. K deficiency affected not only the root morphology, but also the root ultra-structure. The roots of high-efficient genotypes had stronger tolerance to K deficient stress for root membrane damage, and could maintain the developed root architecture to adapt to the low K growth medium.
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Received: 14 January 2008
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