INCREASE OF SEED YIELD AND PHYSICAL QUALITY IN A PINUS-RADIATA CONTROL-POLLINATED MEADOW SEED ORCHARD

Experiments were initiated to increase seed yield and physical quality in a New Zealand Pinus radiata controlled pollinated (CP) seed orchar d. To do this an irrigation treatment; and other treatments such as gi rdling, foliar fertiliser and hormones, were applied during the period of rapid cone growth commencing some 14 months after pollination. Irr igation significantly increased cone growth and seed yield; giving e.g . an increase of 53% in cone fresh weight, 39% in seed weight, 31% in the number of filled seeds per cone and 53% in seed germinative energy . Girdling and foliar fertiliser application also increased cone and s eed parameters to comparable levels, but only in the absence of irriga tion. Hormone application was ineffective unless combined with girdlin g or foliar fertiliser treatments. While the results were based on onl y 2 clones, the magnitude of the increase in seed yield would indicate a potential for significant returns from commercial application of th ese treatments.