Study On The Effect Of Soil Moisture And Temperature On Tea Plant Growth

Tested tea plants have representative growing curves of the relative growth increment(Y) over growing time (T) as the following:Y=3.1660/1+e^{2.65915-0.04849T} (F=31.70,R²=0.6252,P<0.01)The maximum relative growth increment of each tested tea plant is 3.1660 grams dryweight per gram dry weight。From March 3, the date of shoots stating, tea plants reachtheir maximum growing speed , 0.03838 grams dry weight per gram dry weight on the55th day. From the 28th day to the 82nd day is the vigorous growing period of tea plants,achieving 65.84% of their maximum relative growth increment.Each fundamental growing curve of tea plants of each soil moisture reaches the mostsignificant level. 76%±6%, proportion taking up the maximum water hold capacity, is themost suitable for tested tea plants, taking up the maximum relative growth increment, Andwith the increasing of the soil moisture stress intensity, the maximum relative growthincrement is decreasing.However the most suitable soil moisture group does NOT own themaximum growing speed. The maximum growing speed has the trends of descending afterrising first ,with the increasing of the soil moisture stress intensity. And the moment of themaximum growing speed of the tea plants of the most suitable soil moisture is NOT theearliest.With the rising of the soil moisture stress intensity, the maximum growing speedhas the trend of lagging after leading first. The initiating moment, the ending moment andthe span of the vigorous growing period are consistent with the trend of the maximumgrowing speed. The characteristic worth GT, which is the growth increment within thevigorous growing period, has the trend consistent with the maximum relative growthincrement.The ratios of the relative growth increment achieved within the vigorousgrowing period over the maximum relative growth increment of tea plants of each soilmoisture have no difference. They are NOT affected by the soil moisture.Tea plants of the most suitable soil moisture (76%±6%) enter its vigorous growingperiod when the effective accumulated temperatures reach 93.52℃,reaching its maximumgrowth speed at the moment when the effective accumulated temperatures reach 286.65℃,ending its vigorous growing period at the moment when the effective accumulatedtemperatures reach 574.09℃, and having used 480.57℃effective accumulatedtemperatures within the vigorous growing period. With the increasing of the soil moisturestress intensity, effective accumulated temperatures to reach the maximum growth speedincrease after decreasing first. The effective accumulated temperatures, which the tested tea plants require to go in, through and out of the vigorous growing period, keep pace withthe trends of the effective accumulated temperatures required to reach the maximumgrowing speed.The modelY=C/1+e^{a₀+a₁K+a₂TK}can reflect on the most significant level the relation of the relative growth increment (Y)and the growing time (T) and the effective accumulated temperature (K).The fitted formulaof every soil moisture group all reach the most significant level.The host effect of the soil moisture on the relative growth increment reaches the mostsignificant level (F = 4.88, R2 = 0.9047, P <0.01). The three-factor model of relativegrowth increment (Y) over the effective accumulated temperatures (K), the growing time(T) and the soil moisture (W)Y(T,K,W)=-17.3754+60.8131W-39.7410W²/1+e^{2.9079-0.0123K+0.00008464TK}reaches the most significant level (F=118.26, R²= 0.4535, P<0.01). Accumulated accordingto the fitted formula, 76.5% is the most suitable soil moisture for tea plants, and the lowerlimit is 38.0%. Tea plants stop growing when the soil relative moisture is lower than 38.0%.The maximum relative growth increment (Y_max) on any level of practical soil moisture (W)can be accumulated according to the fitted formulaY_max=-17.3754+60.8131W-39.7410W².