A controlled water table irrigation system (CWT) automatically provides water to plants. One edge of a capillary mat, on the bench surface, draws water from a trough (water table) below the bench. Each treatment trough was 30 cm long. As the distance between the water surface and the bench surface increases, the water in the growing medium decreases, the air increases; and the water potential decreases. In previous studies a constant CWT of 2 cm below the bench surface was the optimum placement for producing 15-cm pots of geranium. In this study the water table fluctuated between two distances below the bench surface. The fluctuating treatments were 2 cm to 3 cm, 2 cm to 4 cm, and 1 cm to 4 cm. The control treatment remained at a constant 2 cm below the bench surface. The fluctuating treatments were established by using two liquid level controllers connected to a switching mechanism that allowed the water table to fluctuate between the treatment settings. The rate of movement from the higher level to the lower level was determined by the rate of transpiration and evaporation occurring in individual treatments. The amount of water used for each treatment was determined by counting the number of times the solenoid turned on and multiplying this by the amount of water added to the trough. The leaf area and dry weight were the same for plants grown in 2 cm, 2 to 3 cm, and 2 to 4 cm treatments and these treatments were significantly greater than plants in the 1 to 4 cm treatment. The amount of water used by all treatments was nearly the same.
Alternative use for float system greenhouse space is being studied in Kentucky. High sugar sweet corn (Zea mays L.) cultivars direct seeded into cool soils germinate poorly. A float transplant production system was used to produce high sugar sweet corn transplants that could be planted into cool soils. 100 seeds of sugar enhanced (se) 'How Sweet It Is' and super sweet (sh2) 'Early Xtra Sweet' sweet corn cultivars wars seeded into trays with a cell size of either 19 or 49 ml/cell. The trays were floated on heated or unheated water in the greenhouse. Percent germination was significantly influencedby cultivar. A greater percent germination was observed for 'How Sweet It Is' compared to 'Early Xtra Sweet' and for seeds sown in the 49 ml/cell trays compared to the 19 ml/cell trays. No significant differences resulted from varying the water temperature. Transplants were planted into cool soils with direct seeded sweet corn on April 21, 1992. The use of transplants resulted in a significantly greater plant stand and a two week earlier harvest than the use of the direct seeding.
Three landscape fabrics, Magic Mat®, a heavy black plastic woven fabric with a fuzzy underside; Weed Mat®, a thin black plastic sheet with small holes; and Typar®, a dark gray spun bonded material, with and without a cover of organic oak bark mulch, were evaluated for weed control and ability of strawberry plant roots to establish through the fabrics over a 4-year period. Landscape fabrics reduced weed numbers for the first 3 years in comparison with the bare ground treatment. With few exceptions. the organic mulch did not improve the weed control capability of landscape fabrics. Fruit yield for the Weed Mat and Magic Mat treatments did not differ from the bare ground treatment, but was lower for the Typar treatment when averaged over organic mulch treatments. Fruit yield was higher where the organic mulch was used when averaged over all landscape fabric treatments. Fruit size was slightly larger for the bare ground and smallest for the Typar treatments during the first harvest season, but there was no difference in fruit size by the third year of harvest. Fruit size for the organic mulched plots was slightly larger than that for the unmulched plots the second year of harvest, but there was no difference for the first or third years. The number of strawberry runner plants that rooted and plant row vigor were greater for the Weed Mat, Magic Mat and plots without the landscape fabric than for the Typar plots, particularly in the second and third season. Rooting of runner plants and plant row vigor was better with organic mulch. Landscape fabric tended to reduce extent of rooting, especially in the first season, but it was improved by the application of organic mulch.