亚热带种子园取得的产量超过了美国南方松产区种子产量的好几倍。较温暖的气候,花开得也早,这一有利的条件,可使产量提高30％(Smith 1975)。1976年,一些合作组织在得克萨斯州格兰得河流域选择了一块低地作为试验种子园。要求是要在火炬松、湿地松自然分布区之外的亚热带气候区内,因此,种子园选在得克萨斯州麦克阿兰附近,约距自然南方松产区400公里。在那里建立5个火距松和1个湿地松种子园。每块试验地使用一个产区的无性系,这些无性系是在开雌花由差到好这个范围内选择出来的。供试接穗是由北卡罗来纳州立大学树木合作组织、佛罗里达树木合作组织和西海湾树木改良计划成员们提供的。 第一批种子园于1976年定植,共140株(嫁接苗136株,实生苗4株)。使用的株行距是9.5×9.5米。授粉树的无性系都是从适宜的地区和品种中选出来的,并能够产生大 Subtropical seed orchards made more than the United States south of the pine seed yield several times. Warmer climates, with flowers blossoming early, provide favorable conditions that increase yields by 30% (Smith 1975). In 1976, a number of cooperatives selected a lowland as a pilot seed orchard in the Grande Basin, Texas. The requirement is to be in a subtropical climatic zone outside the natural distribution of Pinus taeda and Pinus elliottii so that the seed orchards are located near McAllan, Texas, about 400 km from the natural southern pine producing area. There, five fire pine and one wetland pine seed garden were established. One clonal line was used for each trial, and the clones were selected from the range of poor to good female flowers. The scion was provided by members of the North Carolina State University Tree Cooperative, the Florida Tree Cooperative and the West Bay Tree Improvement Program. The first batch of seed orchard was planted in 1976, a total of 140 (grafted 136, 4 seedlings). The row spacing used is 9.5 × 9.5 meters. Pollinating tree clones are selected from the appropriate regions and varieties, and can produce large