GROWING OLIVES IN TEXAS; REGULATION OF FLOWERING IN `ARBEQUINA'

Abstract

Olives have not been commercially grown in Texas because earlier investigators considered Texas climate inappropriate for olive cultivation. No experimental investigations were conducted in Texas. Olives, however, grow in very diverse climatic conditions throughout the world, and >2000 cultivars of olives have been reported worldwide. To study temperature regulation of flowering in olives, relatively inexpensive growth chambers were developed. These walk-in type growth chambers can be made with about $7K where as costs of similar size commercial chambers could reach to $100K. Using these chambers we have discovered that flowering and fruiting in `Arbequina' cultivar of olives could be achieved under mild conditions with almost no typical chilling (<7 °C) hours. We postulated that it is the high daytime temperature that prevent flowering in olives in southern Texas rather than lack of chilling hours. Further experiments demonstrated that subjecting trees to 24 °C for 4 hours everyday during winter could significantly reduce flowering in Arbequina. It appeared that several sites near coastal Texas, particularly Galveston, may not experience high daytime temperatures and hence could be suitable for olive cultivation. Trees have now been planted in these sites, but serendipitously several olive trees, >25 years old, were found in Galveston that had been flowering and fruiting for years. Olive accessions have also shown adaptability to local climates at various other sites in Southern Texas. Our initial surveys of olives groves established during the last 4–6 years have revealed the existence of at least two trees with remarkable adaptability to Texas conditions. One of these trees had flowered and fruited in the Rio Grand Valley where earlier workers had predicted that flowering in olives will not occur. Thus, there appears some genetic diversity and clonal variations among limited number of existing olive trees in Texas that there is a hope for viable cultivations of olives in Texas. Clones from these trees have now been produced which will be planted at various locations within the Texas Valley to evaluate their performance in the next few years.