Combined effects of short-day treatment and fall fertilization on growth, nutrient status, and spring bud break of Pinus tabulaeformis seedlings

Abstract

Abstract: Although effects of short-day treatment and fall fertilization on seedling development have been studied independently, their combined influences are not well elucidated. We explored growth, nutrient concentration, and spring bud break of Chinese pine (Pinus tabulaeformis Carr.) seedlings exposed to two photoperiod treatments (short-day consisting of 3 weeks of 18-hr nights in late summer and ambient day length) and three rates of fall N fertilization (0, 12 and 24 mg N per seedling). Seedlings were assessed before fall fertilization and at the end of the growing season. Bud break timing was evaluated the following spring. Increased foliar P concentration concurrent with reduced root P and K concentration occurred in short-day treated seedlings at the conclusion of photoperiod treatment. By the end of the growing season, short-day treatment resulted in greater N and P concentration in the stems, and P concentration in the foliage. It also induced smaller foliage and stem dry mass in both stages. Fall fertilization consistently enhanced tissue N concentration, but interaction effects with short-day treatment were generally non-significant. Short-day treatment curtailed shoot growth, induced terminal bud set, and hastened spring bud break (by only one day) for this mid-latitude seed source (41° N). Thus, short-day treatment or fall fertilization each promoted an increased nutrient concentration, while having only a minor effect on spring bud break.