The influence of root-zone temperature on growth of Betula pendula Roth.

Abstract

We have examined shoot and root growth and the concentration of carbohydrates in seedlings of a northern (67 • N) and a southern (61 • N) ecotype of Betula pendula Roth. cultivated at root-zone temperatures of 2, 6, 12 and 17 • C. Three hydroponic experiments were conducted in controlled environments. We used three different pretreatments before seedlings were subjected to the experimental temperature treatments. Actively growing seedlings that were acclimated to the hydroponic solution for 3 weeks at a root temperature of 17 • C, continued to grow at all the experimental temperatures, with an expected increase in growth from 2 to 17 • C. However, if we started with ecodormant cold stored plants or used seedlings grown actively in perlite, no growth was observed at 2 • C and only minor growth was found at 6 • C. The highest root temperature always produced the best growth. The concentration of nonstructural carbohydrates was higher in seedlings grown at 2 • C than at 17 • C, and this is probably due to extensive incorporation of carbohydrates into cell walls and other structural elements at 17 • C. We found no evidence for differences between the two ecotypes in root growth, in timing of bud burst, but shoot growth terminated in the northern ecotype in the first experiment because the natural photoperiod was below the critical value. Our study highlights the importance of post-transplantation stress (planting check) related to root growth, and that root threshold temperatures may change according to the way plants are pretreated.

Effects of root-zone temperature and N, P, and K supplies on nutrient uptake of cucumber (Cucumis sativusL.) seedlings in hydroponics

“…Numerous studies on different species have shown that plant growth is greatly influenced by root temperature (Lyr and Garbe 1995;Lahti et al 2005;Solfjeld and Johnsen 2006;Díaz-Pérez et al 2007;Nxawe et al 2009). Actually, plant growth is controlled by various factors, especially root temperature and nutrient supply.…”

Temporal dynamics of nonstructural carbohydrates and xylem growth inPinus sylvestrisexposed to drought

“…Hence, the pool of NSC is a measure of the carbon source-sink relationship within a plant (Chapin et al 1990;Hoch 2007). Recently, several studies found that the NSC pool, especially starch and low molecular weight sugars like glucose, fructose and sucrose, increased in conifers in response to growth-limiting low temperatures at tree line sites (e.g., Solfjeld and Johnsen 2006) indicating that sink activities (i.e., structural growth) were more restricted by low temperatures during the growing season than source activities (i.e., carbon assimilation). In mature temperate conifers at low altitude where favorable growing conditions prevail, NSC did not vary significantly throughout the growing season .…”

Study of Nutrient Solution Management in Soilless Rose Cultivation Through the Analysis of Physiological Parameters and Nutrient Absorption

“…The assimilates production is generally higher in spring than in winter due to higher light and air temperature, and a use of reserves is normal in woody plants in this period. An increase in the content of carbohydrates has been described in many species under winter conditions: maize and wheat (Engels, 1994;Guedira and Paulsen, 2002), birch (Solfjeld and Johnsen, 2006) and roses (Schrock and Hanan, 1981;. Storage and mobilization of carbohydrates reserves are essential for winter survival and regrowth of perennial plants in spring (Loescher et al, 1990).…”

“…The decline in photosynthetic activity results in the reduction of shoot growth, shoot dry weight and/or leaf area under both supra-optimal (Kafkafi, 2008) and infraoptimal root temperatures (Ali et al, 1996;Sanders and Markhart, 2000;Franklin et al, 2005;Solfjeld and Johnsen, 2006;Apostol et al, 2007;Malcolm et al, 2008;Field et al, 2009). A high root temperature may also accelerate the senescence of aerial parts and may reduce the shoot dormancy period and the subsequent level of floral initiation (Guedira and Paulsen, 2002;O'Hare, 2004).…”

“…Under low temperatures, the leaf content of total nonstructural carbohydrates increases (Ali et al, 1996;Repo et al, 2004;Solfjeld and Johnsen, 2006). This been attributed to a lower partitioning of assimilates into structural carbohydrates (Solfjeld and Johnsen, 2006), a delayed loss of starch (Repo et al, 2004), a reduction of translocation (phloem loading/unloading) or a decrease of root sink demand (Sanders and Markhart, 2000). In contrast, some authors (Ali et al, 1996; Chapter 4.2 of this thesis) have measured an increase of carbohydrates in the roots, which has been associated with tolerance to low root temperatures (Kanda et al, 1994).…”