Effects of Elevated Water Temperature on Growth of Basil Using Nutrient Film Technique

Hydroponic systems have become increasingly popular for growers in recent years for year-round local production. Whereas optimal air temperature for plant growth has been considered, optimal root zone temperatures have not been examined as thoroughly. The objective of this research was to determine the optimal water tempera-ture for growing different types of basil hydroponically. Research was conducted at the greenhouses in Stillwater, OK. Seventeen cultivars were selected from six main types of basil and transplanted into Nutrient Film Technique hydroponic systems, and three wa-ter temperature treatments were applied: 23, 27.5, and 31 degrees C. Height, width, average leaf area, leaf number, chlorophyll concentration (chlorophyll readings obtained with the Minolta-502 SPAD meter), shoot fresh weight, shoot dry weight, and root dry weight were evaluated. In general, the 27.5 and 31 degrees C treatments were not greater than each other in terms of leaf number and root dry weight but were greater than the 23 degrees C treat-ment. The 31 degrees C treatment had the greatest height, whereas width, average leaf area, shoot fresh weight, and shoot dry weight were not different from the 27.5 degrees C treatment. The 23 degrees C treatment had the greatest chlorophyll concentration (SPAD) value. Cultivar differences were significant in average leaf area and SPAD, with 'Spicy Bush' having the smallest leaf area and purple basil having the greatest SPAD value. For all cultivars ex-cept purple basil and 'Large Leaf Italian', a 27.5 degrees C water temperature would be recom-mended for greater plant growth.

Automated summary

The study aimed to determine the optimal water temperature for hydroponic cultivation of different basil varieties, and found that a water temperature of 27.5 degrees Celsius can promote the growth of most cultivars.