On the Relation of No-water-supply Days to Survival Percent and Soil Water Content in Trees for Landscaping

Abstract

With a view to elcidating the relations between no-water-supply (days) and soil water content (%) and survival rate (%) in trees for landscaping, the present study was conducted in 1984 by pot experiment, Eurya emaginate and Rhododendron indicum being selected as materials. Soil used, subsoil of Andosol. Fifteen levels of no-water-supply (days), in Eurya, 0, 18 (1) 22, 24 (2) 40days, in Rhododendron, 0, 25 (1) 29, 32 (3) 56 days.
In regard to changes in soil water content (%) in the pot by no-water-supply (days), fitting of modified exponential equation curve was done.
The model in Eurya.
YE=15.01+24.60e^-0.0599xx: no-water-supply (days)
Themodel in Rhodod6ndron.YR=24.85+18.68e-0.0546xx: no-water-supply (days)
With regard to changes in the regression equation (Ootsuka's type-8 method-A) survivalrate (%) by no-water-supply (days), fitting of Ootsuka's by intersecting straight lines was done inbothapecies.
As for Eurya, the following regression equation by intersecting straight lines was obtained, the first (I₁) and second (I₂) intersecting points being 19.000 and 37.000days, respectively.
As for Rhododendron, the following regression equation by intersecting straight lines was obtained, I1 and I2 being 41.000 and 44.750days respectively.
YE=2.0475X₀-0.55312_x1YR=11.370_X0-0.25092_X1
xo, x₁: values obtained from data matrix of minimum error variance
It was seen the experiment that Rhododendron survived for longer a time than Eurya nuder field conditions or in to conduct experiments in other soils.