Differential response of half-sib families of American sycamore (Platanus occidentalis L.) to contrasting moisture, pH, and fertilizer conditions

Abstract

This study was initiated to determine if differential response in growth and uptake of nutrients occurred among open-pollinated families of American sycamore when they were subjected to all combinations of three moisture levels, three pH levels, and three fertilizer concentrations in a greenhouse. A majority of the variation in survival was attributed to the main effects. Survival increased with increasing moisture, decreasing pH, and decreasing fertilizer concentration. The families from southwest Texas survived best and those from northeast Texas the poorest. Some families survived well over all conditions suggesting that selections for increased survival could be made. Seedling growth under alkaline pH was less than under acid conditions. The best overall growth for height, diameter, and stem weight occurred in the high moisture x neutral pH x medium fertilizer plots. Although survival was best among the west Texas families, growth was generally poorest for these families. Root weight decreased with increasing fertilizer in the acidic and neutral pH treatments hut this trend was reversed in the alkaline treatments. Root weight of the western families increased under the medium moisture level. Family variation in these growth traits was large enough in magnitude that gains in seedling size can he made by selecting the best families. Genotype x environmental interactions were found to be significant in several instances hut the magnitude of the variation attributed to them was relatively small in comparison to the total genetic variation. The content of potassium and sodium in the leaf tissue increased with increasing pH, whereas the content of calcium decreased. All elements analyzed increased with increasing fertilizer concentration. Families and geographic sources differed in their ability to absorb potassium, calcium, and magnesium. A significant fertilizer x family interaction indicates that nitrogen, potassium, calcium, and sodium are differentially taken up depending on the fertilizer concentration. However, the magnitude of this variation was small..