A Comparison on the Early Growth of Cutting Stock and Seedlings of Slash Pine × Caribbean Pine F1 Hybrids

The cutting stocks and seedlings of 7 full-sib families of slash pine (Pinus elliottii var. elliottii） × caribbean pine (P. caribaea var. hondurensis） F1 hybrid were planted in a trial in Taishan (22°11′N,112°49′E）. The test was measured at age 1 for survival and height; and at age 3, 4 for height, diameter at breast height (DBH）. The average survival rates of cutting stocks and seedling were 97.19% and 97.55%, respectively. All hybrid families performed better than seed-lot of slash pine first-generation seed orchard in Taishan, at the age of 4. Relative realized gains of cutting stocks and seedlings of the slash pine seed-lot were 29% and 26%, 34% and 34%, 133% and 135%, for height, DBH and volume, respectively. The total growth of cutting stocks was slower than that of seedlings, in the first 3 years. But the increment of cutting stocks increased gradually, and it exceeded the seedlings at the age of 4. It was suggested that the cutting stocks or seedlings of superior hybrid families could be planted extensively in the southern region of China.