Effect of temperature and light intensity on the growth and flowering of Odontoglossum intergeneric hybrids

To develop a more efficient method of growing of Odontoglossum intergeneric hybrids, two experiments were conducted to determine the effects of temperature and light intensity on the growth and flowering of these hybrids, and on nutrient absorption. Exp. 1. Effects of temperature: 1) The rates of increase in expanded leaf area, chlorophyll density, bulb diameter, root length, and dry matter were fastest at 18 degrees C. 2) Loaf area expansion occurred earlier in plants grown 25 degrees C than in those kept at 18 and 11 degrees C by four and eleven weeks, respectively. 3) The nutrient concentrations varied little among the plots except for a high P level at 18 degrees C, the total nutrient absorbed by the plants was greatest at 18 degrees C. The amounts of nutrients other than N and P were also considerably increased at 18 degrees C. 4) The optimum growth occurred at 18 degrees C; but the flower stalks elongated and bloomed the earliest at 25 degrees C. Exp. 2. Effects of light intensity: 1) At lower light intensity (87.5% shade), the expanded leaf area was largest, but the development of other organs was most retarded compared to plants exposed to higher light intensities. 2) Low light intensity resulted in the highest N, P, K content. Although the amounts of N, P and K absorption were not greatly influenced by light intensity, Ca absorption decreased at low light intensity. 3) The number of flower stalks was not affected by low light intensity, but the anthesis was delayed about 10 days. 4) the rate of growth, the amount of nutrient absorbed and the number of flowers did not vary among the light plots, but chlorophyll density decreased and many leaves were burned under high light intensity (50% shade). We conclude that the optimum conditions for growth and flowering of these intergeneric hybrids are moderate light intensity (68% shade and 18 degrees C