%0 Journal Article
%T Water Treatments and Root-Shoot Growth Relations in Yemane ( Gmelina arborea roxb.) Seedlings
%J -
%D 2017
%X The nursery study was conducted to provide a scientific explanation for the practice of hardening seedlings in the nursery prior to out-planting in the open field. Three watering treatments (unstressed condition (US) seedlings watered twice a day, moderately stressed condition (MS), seedlings watered once a week, and severely stressed condition (SS), water is applied when seedlings show symptoms of mid-day wilting) were applied to Yemane seedlings ( Gmelina arborea Roxb.) and their effects on root-shoot growth parameters were measured. Yemane was selected as the test species considering their massive use for reforestation in the Philippines. The experiment was laid in a Randomized Complete Block Design (RCBD) with each treatment replicated 6 times. Data was obtained for a period of four (4) months and the ANOVA for RCBD was used to test level of significance among the treatments. The Duncan¡¯s Multiple Range Test (DMRT) was used to compare treatment means. Shoot height, stem diameter, leaf area and shoot biomass and root length, root diameter, root density and root biomass were the parameters measured for above and below ground, respectively. Water treatments influence biomass partitioning responsible for the changes in seedling morphology and architecture. Seedlings in unstressed condition has bigger basal stem diameter, longer shoot length and wider leaf area. Furthermore, seedlings in unstressed condition obtained the largest volume of green shoot biomass but when ovendried has lighter weights, compared to the moderate and severely stressed seedlings. Severely stressed seedlings obtained the largest biomass gain in the number and length of lateral roots, root density, root biomass, root: shoot ratio and the production of a more fibrous root system. Water stress treatments suppressed the elongation of shoot parts but promotes increases in root parts. In the same manner, water treatments influenced source-sink relation between root and shoot parts wherein carbohydrates accumulates in the leaves and stem of seedlings in unstressed condition but shift to the roots in moderate and severely stressed condition. The shift in carbon allocation is an adaptive mechanism for stress regulation accounting for the larger increment in root parts under water stressed environment. It is clear that water stress treatments modified root and shoot morphology and it can used as a hardening tool for seedlings during the nursery tending phase.
%K Water Stress
%K Water Treatment
%K Root Growth
%K Shoot Growth
%K Hardening Treatment
%U http://www.sciencepublishinggroup.com/journal/paperinfo?journalid=218&doi=10.11648/j.ajaf.20170502.13