Procedures are presented for incorporating the estimated variances from an experimental population into the calculation of parameters required to design experiments which will be able to detect specified mean differences among treatments within the population. Relationships between the estimated variances and the number of replicates per treatment and the number of apples per replicate were investigated using theoretical populations constructed from pressure test data from ‘McIntosh’ and ‘Jonathan’ apples (Malus domestica Borkh.). Analysis of these populations showed that the number of apples per replicate and replicates per treatment can be more efficiently reduced by selecting uniform populations than by attempting to further reduce errors associated with the operator or equipment. Four pressure tests per apple resulted in the optimal reduction in the estimated variance of the replicate mean; a sensitive factor in determining the values of design parameters. Estimated variances decreased with storage time. Therefore, experimental designs constructed on the basis of analyzed preliminary pressure tests will be adequate for the duration of storage experiments in which the variability of the population is not increased by the treatments.
Standing freshly harvested 21-cm asparagus spears (Asparagus officinalis L.) in 50 ml of 1 mg·liter−1 to 10 g·liter−1 aqueous glyphosate solutions significantly decreased toughening and the amount of fiber and lignin in spears stored at 2.5°C for 10 or 20 days. The effect increased with storage time and concentration, but decreased with distance from the cut end. Depending on the time of harvest and length of storage, 1 g·liter−1 glyphosate increased the usable portion of the spear from 40% to 60%. Chemical name used: N-(phosphonomethyl)glycine (glyphosate).
A simple, inexpensive method is presented to prepare an effective chemical scrubber which oxidizes volatile organic contaminants in gases. The scrubber is made by mixing 100 ml of 1 M KMnC4 per liter of dust-free Perlite in a large clear plastic bag.
Mature green bell pepper fruit (Capsicum annuum L. cv. Yolo Wonder) exhibited a non-climacteric pattern of ethylene and carbon dioxide production during normal ripening and red color development at 24°C. Exposing detached mature green fruit to 500 ppm propylene in air for 48 hours, did not induce an increase in ethylene or carbon dioxide production. Wounding excised plugs of ovary wall tissue caused an increase in carbon dioxide production within one day, and an increase in ethylene production by the second day.
A 10-minute soak in 1.0 mm vitamin K5 reduced ethylene production over 90%, while doubling carbon dioxide production by cortical tissue from pre-climacteric apples (Malus domestica Borkh.). Reduced ethylene production persisted for at least 4 hours, while carbon dioxide production declined to rates not significantly different from the controls. Vitamin K5 also reduced ethylene production by 50% from quartered fruit of tomato (Lycopersicon esculentum Mill.) at different stages of maturity, and from cortex tissue from apples at or near their climacteric peak of ethylene production.
Gas samples are often extracted from horticultural produce for analysis of ethylene, carbon dioxide, oxygen, and other gases by gas chromatography. This paper outlines procedures for extracting gas samples either by using a syringe needle to puncture a cavity within the fruit or vegetable or by subjecting the fruit or vegetable to a partial vacuum.
A device is described which maintains a set temperature ± 0.8°C from 5 to 30° above ambient in an inexpensive controlled-temperature chamber. Present construction cost is about $65. Ten chambers have performed satisfactorily during the past 3 years in research projects on chilling injury, seed germination, seeding growth, tissue culture growth, fruit storage, tree storage, and winter dormancy.
A 39-week production schedule is described in which container-grown apple trees (Malus domestica Borkh. cvs. Red Chief Delicious, Sundale Spur Golden Delicious, and Paulared) are cycled through 4 weeks of cold acclimation, 7 weeks of chilling, 5 weeks of growth before flowering, 21 weeks of fruit growth and maturation, and 2 weeks growth after fruit harvest.
A survey was conducted to measure the variability among gas chromatographic analyses of ethylene and the variability among the ethylene gas standards used in 22 laboratories in the United States and Canada. The linearity of gas chromatographic responses to injections of 10.0, 1.0, and 0.1 μl/l ethylene in air mixtures had an average coefficient of linear determination (R2) of 0.9984, with a SD among the R2 values of only 0.33%. The ethylene concentrations calculated for the laboratory standards varied from 11.3% higher to 21.7% lower than the value assumed by the participant; with an average variance of about 6% lower.
Prolonged physiological studies using gas mixtures containing μl/liter levels of a specific gas component (e.g. ethylene or propylene) require a flowthrough system to ensure that the plant or plant part under study is exposed to a relatively constant gas concn. This prevents tissue incorporations and/or emanations (e.g. biosynthesis of ethylene or CO2) from altering the physiological effective gas concn (1).