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Abstract
Root growth of pine (Pinus mugo var. mughus (Scop.) Zen.) was studied at a rhizotron (underground root observation laboratory) on an in situ basis. Greater root elongation occurred in peat than in mineral soil and when there were sustained periods of temperature extremes, root growth increased or decreased 2 to 5 days following increases or decreases in soil temperature.
Roots of poplar (Populus alba var. pyramidalis Bunge), grown in glass-sided boxes under controlled growth conditions, suberized more quickly when exposed to natural and artificial light than when kept in the dark.
Abstract
Softening of ‘McIntosh’ apples (Malus domestica Borkh.) during storage was reduced by dipping fruit 2 days after harvest in 4% CaCl2 solution (40 g of commercial CaCl2 in 1 liter of water). The addition of Keltrol, a commercial food thickener, at 3 g/liter to retain more Ca solution on the fruit increased the effectiveness of the treatment. After 4 months storage at 0°C, fruit treated with CaCl2 and with CaCl2 plus Keltrol was 0.30 and 0.56 kg firmer by the pressure test than untreated fruit.
Abstract
Each of 11 cultivars of sweet corn (Zea mays L.) was presented to red-winged blackbirds (Agelaius phoeniceus L.) in an aviary under no-choice conditions in 1985. This evaluation was repeated in 1986 with eight cultivars, five of which had been tested in 1985. In both years, there were significant differences in damage among cultivars; the damage rankings of the cultivars tested in both years were correlated. Total husk weight and husk weight beyond the cob tip individually explained 68% to 69% of the variation in damage among cultivars. Husk characteristics were more important than kernel characteristics in determining the amount of damage a cultivar received. Six of the cultivars evaluated in a field test near a blackbird roost showed differences in damage similar to that found in the aviary. In the field test, the most- and least-resistant cultivars had 16% and 76% of the ears damaged, respectively. Resistance is a viable approach to reduce damage in situations where sweet corn is grown near concentrations of blackbirds.
Abstract
In situ root growth of young plum trees (myrobalan rootstock on which ‘Shiro’ plum was budded) was studied for one season at the University of Guelph rhizotron. Root growth of this combination, at the field-transplant stage, began before leaf growth and extended past leaf fall. Relatively large roots of myrobalan stock made some winter growth in length, below frost penetration. The rate of growth during July to mid-September was twice that of the balance of the season, corresponding closely to shoot and trunk increments. Root diameter and elongation rate are positively correlated. Irregular and patchy suberization was the rule with the young plum roots.