01584naa a2200241 a 450000100080000000500110000800800410001910000210006024501190008126000090020052009040020965000120111365000160112565300180114165300160115965300220117565300220119765300140121970000200123370000180125370000180127177300530128916481962023-04-18       1982    bl uuuu     u00u1 u    #d1 aVENDELAND, J. S.  aAssumptions of plastochron indexbevaluation with soya bean under field drought conditions.h[electronic resource]  c1982  aErickson and Michelini (1957) derived the plastochron index (PI) and aterm sometimes referred to as the plastochron ratio (PR), as quantitative expressions of the vegetative development of plants. With the stable plant growth in environmental chambers and glasshouses, the assumptions used to derive these terms have been validated. However, more recently these expressions are being used to characterize growth under the unstable conditions resulting from the imposition of stress. This study examines the validity of the assumptions used to derive PI and PR for field-grown soya beans [Glycine max (L.) Merrill] subjected to drought stress. Under stress conditions, the assumptions were not satisfied. In fact, observing change in PR appeared to be a good method for detecting drought stress in these plants. Plastochron index; Plastochron ratio; Glycine max (L.); Soya bean; Drought; Leaf growth.  adrought  aGlycine Max  aGlycine max L  aLeaf growth  aPlastochron index  aPlastochron ratio  aSoya bean1 aSINCLAIR, T. R.1 aSPAETH, S. C.1 aCORTES, P. M.  tAnnals of Botany Companygv.50, p.673-680, 1982.