Morphology and foliar chemistry of containerized Abies fraseri (Pursh) Poir. seedlings as affected by water availability and nutrition

• We present the results of a two-year (2007–2008) greenhouse study investigating the effect of water availability and nitrogen fertilization on the growth, biomass partitioning, and foliar nutrient content of Abies fraseri (Pursh) Poir. • Fertilizer and moisture content (irrigation) were varied in a factorial experiment combining four levels of irrigation and three levels of fertilization to evaluate growth and foliar nutrient content. In addition, a numerical optimization was used to estimate appropriate levels of each factor necessary to achieve simulated goals for response variables. • Irrigation increased the height growth by 12 to 35% depending on the fertilization treatment (p = 0.0001). Fertilization increased height growth by 10 to 26% (p = 0.02). A similar response was observed for stem diameter growth (SDG). Total biomass accumulation increased as result of positive response of stem and root biomass development, and foliar nitrogen content was positively affected by nitrogen fertilization and negatively affected by irrigation. The numerical optimization for simulated target growth and nitrogen content responses produced levels of input combinations with high desirability factors to achieve the target responses. • These results suggest that nutrient addition is a strong determining factor for early development of this species. The improved growth efficiency in this study is likely attributed to a combination of factors including, improved photosynthetic capacity, decreased stomatal limitations, or increased resource allocation to stems

Water balance in Cucumis plants measured by nuclear magnetic resonance. 2.

Nuclear magnetic resonance (NMR) was used to investigate the effects of changes in root temperature, of changes in the area of root in contact with culture solution and of day/night rhythm on the water balance of a cucumber and a gherkin plant. Results are discussed in terms of water potential, flow rate and resistance using a previously presented model of water balance. As long as water uptake alone is varied, flow rate and water content (or potential) will change in the same direction. In contrast, from that model it is predicted that changes in transpiration will affect flow rate and water content in opposite ways. An experimental verification of this prediction was given in the previous paper. Results obtained by the NMR method are compared to those determined using a dendrometer. The results demonstrate that the NMR method is a valuable tool to study plant water balance and that it can serve as a technique for discriminating between changes in plant water balance that are due to changes in water uptake by roots and those due to changes in transpiration