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Stem-rust-infected leaves of resistant (var. Khapli) and susceptible (var. Little Club) wheats were detached and floated on water and benzimidazole, with and without glucose. Khapli leaves were susceptible on water, resistant on 40 p.p.m. benzimidazole, susceptible on 40 p.p.m. benzimidazole with 1% glucose, and resistant on 60 p.p.m. benzimidazole with 1% glucose. Little Club leaves were susceptible in all treatments. Khapli leaves subjected to treatments that increase the endogenous substrate levels, such as floating on water for 2 to 4 days or spraying with DDT 2 or 3 days before detachment, were susceptible on 40 p.p.m. benzimidazole and resistant or partially resistant at higher concentrations.The progressive decrease in protein of detached leaves on water was interrupted on transfer to benzimidazole, after which some resynthesis of protein took place with a corresponding decrease in the soluble nitrogen fraction. Detached leaves on benzimidazole with 1% glucose had more soluble nitrogen than leaves on benzimidazole alone. There was more alcohol-soluble carbohydrate in leaves floated on water than in leaves on benzimidazole.

Raising ethylene concentration in 0% CO2 and 3% O2 reduced rot development by Gloeosporium album Osterw. in McIntosh apples. The reduction was comparable with that resulting from increase of CO2 concentration to 5% with either high or low ethylene concentration. The effects were similar at room temperature or at 3.3 °C. Ethylene significantly reduced the growth of G. album in vitro in presence of 5% CO2 at 3.3 °C, but not in the absence of CO2 or in either combination at room temperature.

1971. Electrical stimulation and its effects on growth and ion accun~ulation in tomato plants. Can. J. Bot. 49: 1809-1815. The effect of small increments of direct current on the growth and ion uptake in Scotia tomato plants was determined. The natural endogenous current in the plant was first assessed and the current applied to reinforce or oppose the natural with three treatment durations per day. Significant increases in linear growth (5 to 30%) were obtained and also significant increases in uptake by the plants of K, Ca, and P when currents were between 15 and 3 pA per plant with the plant negative to the ground. A reduction in growth occurred when the plants were treated with 15 pA positive to the ground or with any currents of magnitude greater than 30 pA per plant. The increased ion accumulatioil seems not to be merely a passive movement under the applied potential, and it is thought that small currents may stimulate active ion pumps or alter the internal distribution of growth-regulating compounds in a somewhat erratic manner. IntroductionElectrical stimulation of plants is an attractive hypothesis but relatively unexplored scientifically. Both Lund (1931) and Waller (1925) showed that plants exhibit a constantly fluctuating potential difference or gradient, between the aerial part, the root, and the soil. Breazeale et al. (1951) and Breazeale and McGeorge (1953) demonstrated that cation uptake could be stimulated by application of controlled direct voltage and suggested that cation uptake by plants is an electrical phenomenon. Fensom (1957) studied the bioelectric potentials of plants and postulated an electrokinetic theory of transport. He attempted to alter the water intake of freshly cut maple shoots by applied voltage, up to 45 V (1962). Small electroosmotic flows were induced towards the cathode and from time to time a sudden surge of water flowed into the shoots. This surge seems now to be attributed to a summation of action potential~, for not only was the flow of short duration, but it was also associated with artificial guttation.Several workers such as Blackman et al. (1923) andBriggs et al. (1926) have attempted to influence plant growth with applied electricity by suspending a charged network over the plant,