Effects of Water Deficit on Growth of Two Tree Species Seedlings in Changbai Mountains of Northeast China

Abstract

Plants are continuously exposed to environmental stimuli that influence development and growth, and determine productivity. Water deficit occurs when the rate of transpiration exceeds water uptake, and is a component of several different stresses-including drought, salinity, and low temperature. The ability of the whole plant to respond and survive depends on whole-plant mechanisms [1]. The response depends on the species and genotype, the length and severity of water loss, the age and stage of development, organ and cell type, and the subcellular compartment [2]. Resistance to water deficit occurs when a plant withstands the imposed stress, and may arise from either tolerance or a mechanism that permits avoidance of the situation. Wholeplant mechanisms can contribute to the avoidance of water deficit during the plant's life cycle. The determination of the function of an observed response is one of the most complex issues in plant stress biology. In trying to understand responses to stresses involving a water deficit component, many genes induced by periods of water deficit have been identified and characterized [3][4][5]. In an unfavorable environment, plants must withstand multiple abiotic and biotic stresses, and a response observed during one type of stress may in fact have a role in the amelioration of another condition [6].A better understanding of the dynamics of forests under various climate conditions is important to address the mainPol. J. Environ. Stud. Vol. 24, No. 2 (2015), 787-791 Original Research Effects of Water Deficit on Growth of Two AbstractTo understand how temperate coexisting tree species respond to water deficit, the seedlings of two coexisting species, Phellodendron amurense Rupr. And Fraxinus mandshurica Rupr., were transplanted into plastic flowerpots. Three water deficit treatments were used, W1 (60-90% field moisture capacity), W2 (40-60% field moisture capacity), and naturally occurring precipitation (CK), with the aim of investigating the effects of water deficit on the growth of seedlings and competition between them. The result showed that the relative height and diameter of the P. amurense seedlings decreased in the control groups (CP, single P. amurense seedling; CF, single F. mandshurica seedling) but increased in the mixed groups (one P. amurense seedling and one F. mandshurica seedling together) with the water deficit. The water deficit affected the plants by altering the growth of the seedlings and competition between the two species. It was shown that there were greater negative effects on P. amurense due to the manufactured water deficit than on F. mandshurica.