Stock quality and field performance of Pinus patula seedlings produced under two nursery growing regimes during seven different nursery production periods

Two types of containerized P. patula seedlings, referred to as “hard” and “soft” seedlings, were raised by droughting and different fertilizer applications. “Hard” seedlings were raised by applying half the water and a quarter of the fertilizer (0.01 g per seedling 21%N:7.1%P:14.2%K) applied to the “soft” seedlings. At the end of the nursery cultural treatments the two types of seedlings were morphologically distinct. “Hard” seedlings had lower heights, height to root collar diameter ratios and seedling dry masses than “soft” seedlings, but mortality was similar for both seedling types when planted during seven different production periods within the planting season on three sites which differed climatically and geologically. Correlations between mortality and height to root collar diameter ratio (r = 0.76), root to shoot ratio (r = 0.83) and root growth potential (r = --0.69) were obtained indicating that grading of seedlings on these parameters may improve survival. However, it was evident that survival could be significantly improved by identifying the best time of year and conditions for planting, as well as improving stock quality.