Journal of Zhejiang University SCIENCE B
ISSN 1673-1581(Print), 1862-1783(Online), Monthly

2008   Vol. 9   No. 5   p. 427~434

Differential response of root morphology to potassium deficient stress among rice genotypes varying in potassium efficiency

Yan-bo JIA^1,2, Xiao-e YANG^†‡1, Ying FENG^1,3, Ghulam JILANI⁴

(¹MOE Key Laboratory of Polluted Environments Remediation and Ecosystem Health, Zhejiang University, Hangzhou 310029, China)
(²Institute Calibration and Testing for Quality and Technical Supervision, Hangzhou Bureau of Quality and Technical Supervision, Hangzhou 310004, China)
(³Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition, Zhejiang University, Hangzhou 310029, China)
(⁴Department of Soil Sciences, Arid Agriculture University, Rawalpindi 46300, Pakistan)
^‡ Corresponding Author
^†E-mail: xyang@zju.edu.cn
Received Jan. 14, 2008; revision accepted Feb. 4, 2008

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.

Key words: Genotypic difference, Potassium (K) efficiency, Root surface area, Fine root development, Root cell utra-structure
doi:10.1631/jzus.B0710636             CLC number: X5

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