EFFECT OF POLYETHYLENE AND ORGANIC MULCH ON GROWTH AND YIELDS OF 'ARKIN' CARAMBOLA (AVERRHOA CARAMBOLA L.) IN SOUTH FLORIDA

摘要

The effects of mulch treatments on growth and fruit production of 5-year-old 'Arkin' carambola (Averrhoa carambola L.) grafted on open-pollinated 'Golden Star' (Averrhoa carambola L.) rootstock were investigated under field conditions from July 1999 to March 2000. Treatments included: non-mulched soil (control; C); 10 cm thick layer of avocado wood mulch (organic mulch; OM); black polyethylene (BP); black ground cloth covered with a 10-cm thick layer of avocado wood mulch (GC+OM); and ground cloth covered with a 10-cm thick layer of avocado wood mulch and a film of clear plastic (GC+OM+CP). At a 10-cm depth in the soil, mean temperatures for the GC+OM+CP treatment were 1 to 8 C higher than in all other treatments. At 90 and 180 days after imposing the treatments, there were no significant differences in trunk diameter among treatments. However, the mean percentage of change in canopy volume was significantly greater for trees in the GC+OM+CP and GC+OM mulch treatments than for those of the non-mulched control. Non-mulched trees had lighter green foliage and exhibited more symptoms of chlorosis than trees in the other treatments. When ambient air temperatures dropped below about 10 C during Nov. 1999 to Feb. 2000, the percentage of leaf chlorosis and abscission were consistently greater for non-mulched trees than all other treatments. Crop yields were 16 to 50% greater for trees in the GC+OM+CP treatment than in those in other treatments. In the calcareous soils of south Florida, mulching maintained higher soil temperatures compared to non-mulched controls and mulching enhanced carambola tree growth and yields.