Morphological Grading Studies with 1-0 Slash Pine Seedlings

Abstract

SUMMARY Slash pine seedlings were graded on the basis of three morphological characters: (i) Shoot development—eight classes are recognised based on stem, foliage and. bud maturity. Classes 1 to 4 show increasing development of stem lignification, secondary foliage and terminal bud. Class 5 stock are mature and dormant. Class 6 are breaking dormancy. Class 7 are actively reshooting. Class 8 possess a maturing flush shoot; (ii) Root collar diameter and (iii) Shoot length. Subsequent field performance was monitored for up to five years after planting and all three parameters, but particularly shoot development and diameter, influenced seedling survival and height growth. They can be used in routine grading operations as reliable predictors of field behaviour. Optimum outplanting performance was associated with the following specifications: Shoot development: Classes 5 to 8 inclusive; Root collar diameter: 4 mm and over; Shoot length: 15 to 40cm. These are recommended for adoption in defining 1-0 slash pine plantable grade stock.