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Abstract
Dormant rhubarb crowns do not force well until their rest period or physiodormancy (7) has been broken by sufficient chilling in the field during late fall. There are many reports that during exposure of dormant plants to cold, the free amino acids contents change. Asen and Stuart (1) found that dormant leaves and buds of Hydrangea macrophylla showed an increase of some free amino acids after 6 weeks of storage at 4 to 5°C. Another worker (8) reported that in one alfalfa variety there was a 20% increase of acids from August to December. Schneider (4) found that the levels of some free amino acids in leaves of Ilex crenata nigra rooted cuttings changed during storage at cool temperatures. In this study buds and roots of dormant rhubarb crowns were analyzed to determine the free amino acids present and also possible changes in acids levels that might indicate the end of the rest period.
Abstract
Roots of ‘Centennial’ and ‘Julian’ sweet potato [Ipomoea batatas (L.) Lam.] treated with (2-chloroethyl)-phosphonic acid (ethephon) and bedded after removal from 15.5°C storage, consistently produced more early plants in electric hotbeds than did untreated roots. The ethephon treatment also increased midseason production of plants in some tests. Plants from ethephon-treated roots were of the same height and weight as controls in many of the tests. Treating roots with ethephon and then presprouting before bedding did not increase plant production over that of presprouting alone. Early plants from ethephon-treated roots transplanted as well as controls in field tests.
Abstract
In field plantings, root pieces of ‘Centennial’, ‘Julian’, and ‘Jewel’ sweet potato (Ipomoea batatas L.) treated with (2-chloroethyl)phosphonic acid (ethephon) sprouted earlier than controls. Ethephon treatments increased the number of sprouts on ‘Centennial’ root pieces. In some tests, ethephon treated root pieces had increased yields of storage roots. Gibberellic acid (GA) increased the number of sprouts per root piece but did not influence the percentage of sprouted root pieces. GA promoted the growth of enlarged root pieces with few storage roots.
Abstract
Plant production was increased by treating ‘Centennial’ and ‘Julian’ sweetpotato roots with 250 to 1000 ppm GA or 1000 to 4000 ppm CEPA (2-chloroethylphosphonic acid). In general, GA treated plants were taller than controls and CEPA treated plants were shorter. Cutting roots into sections also increased plant production regardless of chemical treatment.
Abstract
P-(β-chloroethyl)-N-isopropyl phosphonamidic acid, a new ethylene-releasing growth substance was as effective as (2-chloroethyl)phosphonic acid (ethephon) in promoting ripening of tomato fruit on the plant. Laboratory tests showed that both growth substances liberated ethylene in increasing amounts as the pH of the solution was increased from 5 to 8. Epicotyls of Phaseolus vulgaris L. floated in solutions of each chemical released more ethylene 4 to 24 hours after treatment started than did epicotyls floated in water.
Abstract
‘Jade Cross’ Brussels sprouts plants treated once with a foliar spray of 3000-4500 ppm succinic acid-2,2-dimethylhydrazide (SADH) when the first 5-6 sprouts were 1.9 cm in diam were shorter, more uniform, and had yields equal to untreated plants. Treated plants, were about the same ht and yielded as well as plants where the terminal bud was removed (topped) by hand. Earlier maturity was obtained by treating plants with SADH at an earlier stage, but yields per plant were reduced. These sprouts, however, had higher levels of Ca and, generally, higher levels of Mn. Plants treated with 4500 ppm SADH, early or late, had medium size sprouts that were firmer than sprouts of the same size from untreated or topped plants.
Abstract
Yellow or blond peas are a serious problem during some years for growers and processors of dark green peas grown for freezing in the Pacific Northwest. Previous reports (6, 10) indicate that most yellow peas in varieties grown for freezing result from insufficient light reaching the developing ovules before they have reached half-size. The senior author has found (unpublished data) that off-color peas are usually in the lower shaded pods and that gibberellin applied at full bloom resulted in more vegetative growth, lodging, and yellow peas.
Abstract
A single foliar spray of 25 or 28 ppm 5-chloro,2-thenyl, tri-n-butyl-phosphoniumchloride (CTBP) when the first flowers opened increased yields of 2 cultivars planted in late summer and 2 of 4 cultivars planted in late spring, 1970. Yield increases were due to more pods. In general, CTBP treatments that increased yields did not influence seed and fiber development, shear press values, and color of 4-sieve and 5-sieve pods that were canned. Also, Ca, Mg, P, and K levels of 4-sieve, deseeded 5-sieve, and seeds from 5-sieve pods were not influenced by CTBP treatments.