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- Author or Editor: H. A. Hughes x
Considerable research on greenhouse energy conservation has been conducted since the escalation of fuel prices began in 1973. A variety of conservation techniques such as air-inflated polyethylene over glass (17) and thermal curtains (8, 24, 25) have been studied. Alternative energy sources such as solar energy (7, 14, 15, 16, 18, 19), waste heat from power plants (26) and deep mine air (23) have been examined. Unfortunately, commercial application of these techniques frequently results in reduced light transmission, growing area or precision of environmental control, offsetting the conservation potential.
Leaves of red raspberry (Rubus idaeus L. cv. Meeker) were sampled every 2 weeks throughout the growing season at 7 different positions on the cane to determine the time and position of minimum leaf nutrient flux. During the last half of August, the 5th to 12th leaves from the terminal 15 cm of the primocane showed the least variation in nutrient concentrations.
Red raspberry (Rubus idaeus L.) is prone to a “white drupelet” disorder on the sun-exposed side of the fruit, largely during those harvest periods when daytime temperatures exceed about 33°C. In mid-August, more than 40% of the fruit were affected. Three types of shade covers (30% and 60% black shade fabric and 25% shade white polyester), placed over raspberry plots for 1 to 3 weeks prior to fruit harvest, reduced the amount of solar-injured fruit from 41% in unshaded plots to between 8% and 16%. Fruit surface temperature was reduced about 4° by both black shade fabrics, but only 1° by the polyester cover. Fans cooled fruit by about 2°, but the reduction in solar injury was less than with shade covers.
Five color types of Alstroemeria ligtu Linn hybrids from one seed source were examined cytogenetically. The somatic chromosome numbers were all 2n = 2x = 16. Karyotype analysis revealed that all five plants had the same chromosome constitution. Chromosome pairs 2,3,5, and 8 had satellites. Chromosome complements of the A. ligtu hybrid were unique in that they contained two pairs of satellite metacentric chromosomes that were not found in any Alstroemeria cultivars.