Study on Rhythm of Annual Height Growth of F₂ off-springs of Pinus elliottii×P.caribaea var.hondurensis and Seedling Breeding Techniques

The Logistic Equation was applied to simulate the annual height growth of F₂ off-springs of Pinus elliottii×P.caribaea var.hondurensis.A regression model of the seedling height(Y) determined by growth time(days presented by X) was established as Y=36.71/(1+53.935 13e^{-0.029 71X})).The tests showed that both the slope(b) and the correlation coefficient(r) reached significant level(p<0.01,r²=0.993 0).The annual height growth of the F₂ seedlings can be logically divided into 3 phases,i.e.the early phase,the peak phase,and the late phase.The relationship of monthly height growth from May to November with some important meteorological data in the corresponding months were analyzed.Some seedling breeding techniques for the variety were suggested.