Effects of nitrogen fertilization, irrigation, and cover-cropping vs disking on nitrogen and soluble sugar composition and on flowering of eight clones of slash pine (Pinus elliottii Engelm.) were studied. Fertilizing with ammonium nitrate increased free arginine, total free amino acids, and total nitrogen of the twigs; and total nitrogen of the needles. Fertilizing also doubled female flower production. Irrigation decreased total foliar nitrogen, and increased male flowering as an interaction with clones. Cover-cropping with a legume (hairy indigo) increased arginine content and decreased soluble sugar content of the twigs, and interacted with irrigation in affecting female flowering. There were highly significant differences among clones in female and male flowering, all measures of nitrogen content, and soluble sugar content. There were also several significant interactions between clones and treatments in affecting flowering and nitrogen composition.
Document Type: Journal Article
Research Forester, Soils and Fertilizer Research Branch, Tennessee Valley Authority, Muscle Shoals, Ala.