Use of Haun's scale for monitoring development of wheat from flag leaf emergence to end of stem elongation.

摘要

Haun's scale of foliar stages allows a continuous numerical expression of plant development until the complete emergence of the flag leaf. The adequacy of an extension of Haun's scale to stages beyond flag leaf emergence, based on observation on theflag sheath and peduncle, was tested in a contrasting set of cultivars (common and spelt wheats), locations (Belgium and Argentina), and water status. The four main post-foliar stages were identified as: 0, corresponding to flag sheath elongation; 1, toflag sheath increase in diameter (booting); 2, to ear emergence; and 3, to the extrusion of the peduncle above the flag leaf ligular zone. The extended scale allowed the monitoring of development during the 3-4 weeks following flag leaf emergence and was sensitive enough to reveal differences at daily intervals. Plots of post-foliar stages versus thermal time were roughly linear, little affected by treatments (cultivar, water status, location) or by discontinuities due to the initial and final value ofthe decimal part of the numerical codes in the intervals between mean stages.