M.j. Arvin, M.h. Banakar,
Volume 6, Issue 1 (4-2002)
Abstract
Bolting in onion reduces yield and quality of bulbs. To control bolting chemically, a glasshouse experiment was conducted using Texas Early Grano which is widely cultivated in subtropical areas of Karman Province. In this research, Paclobutrazol (0, 1000, 2000 mg/lit), ethephon (500, 1000, 2000, 3000, 4000 mg/lit), cycocel (500, .1000 mg/lit) and mixtures of ethephon and cycocel were sprayed on onion plants prior to vernalization. At harvest time, morphological characters (bolting percentage, shoot length, shoot dry weight, bulb maturity index) and biochemical characters (chlorophyll a, b and total in shoots, reducing sugars and soluble proteins in roots, bulbs and shoots) were recorded. Paclobutrazol reduced bolting, reducing sugars, soluble proteins and shoot length but increased leaf chlorophylls, proteins, sugars and bulb weight with no effect on shoot dry weight. Although ethephon reduced bolting, shoot growth, sugars, proteins and leaf chlorophyll and increased maturity index, sugars and proteins in bulbs, it had no effect on bulb yield. Cycocel increased bolting, sugars, proteins, chlorophylls and dry weight in shoots but had no effect on shoot length, leaf chlorophyll, sugars and protein in roots and bulb weight. Cycocel also reduced sugars and protein in bulbs. Mixtures of cycocel and ethephon reduced bolting, leaf chlorophyll, shoot length and dry weight but had no effect on bulb yield and other characters measured.
M. J. Moghbeli Hanzaii, E. Tafazoli,
Volume 6, Issue 3 (10-2002)
Abstract
Alternate bearing is a key factor in limiting citrus production. Chemical controls have proved to be the most effective solution to this problem. Two different experiments were conducted to study the effects of different growth regulators (GA3, NAA, Ethephon) and urea on alternate bearing control in Kinnow mandarin (Citrus reticulata). In the first experiment, GA3 at concentrations of 0, 25, 50, 75 and 100 mgl-1 were applied 3 times during late autumn and early winter 1993 on off trees. Flowers reduced as a result of GA3 application in the following spring but increased in the second spring. Best results obtained with 50 and 75 mgl-1. In the 2nd experiment thinning agents: NAA (0, 100, 200 and 300 mgl-1), ethephon (0, 100, 200, 300 mgl-1) and urea (0, 4, 8 and 12%) were sprayed to the trees on on-year, when the fruitlets were about 0.75-1 cm in diameter. The results indicated that urea had no effect however, both NAA and ethephon were effective on thinning of fruits and control of fruiting. Ethephon at 200 and 300 mgl-1, and NAA at 400 mgl-1 gave the best results.
