Girdling: its effect on carbohydrate status and on reproductive bud and cone development of Douglas fir

Abstract

Partial girdles were applied in August, 1957, to one stem of two double-stemmed, 20-year-old Douglas fir (Pseudotsuga menziesii (Mirb.) Franco). The second stem served as control. A third double-stemmed tree was treated in May, 1958. Cone production responses were obtained on all three girdled stems, averaging 7.4 times that of control stems in 1959, and 1.6 and 2.3 times that of control stems in 1961 and 1962. Cone production responses to treatment, and cone crop variation over several years were correlated with reduced bud failure during the period of new shoot elongation. Total number of buds per shoot was initially similar for paired stems. These relationships indicated a predetermined potential for annual cone production, and that cone crop periodicity is determined by later conditions favorable or unfavorable to continued early bud development. Treatment increased both sugars and starch in shoots sampled 40 days after August girdling, but only starch remained elevated the next spring and throughout the decisive May–June period of reproductive bud development. Other factors indicated food reserves to be related only weakly to reproductive bud survival. Cone production reduced carbohydrate concentration in shoots of all ages, growth and number of new shoots, and number of developed buds per shoot. These factors explain the absence of consecutive cone crops in Douglas fir, and suggest that cone inducing treatments should not be applied in good flowering years. Cone production responses on single-stemmed trees girdled at weekly intervals showed an optimum timing coincident with the onset of flowering, a more variable response up to the time of vegetative bud break, then an adverse effect on cone production when girdled later than 1 week after vegetative bud break.

Promotion of seed production in Douglas-fir grafts by girdling + gibberellin A4/7 stem injection, and effect of retreatment

“…The nutritional drain and loss of potential flowering sites associated with heavy cone bearing can severely depress cone production for several years thereafter (Owens and Blake 1985). There are reports of G and GA treatments having a positive carry-over effect on cone production in subsequent years (Ebell 1971;Pharis et al 1980;Philipson 1985Philipson , 1987Bonnet-Masimbert 1987;Bower et al 1989). In contrast to the present study, however, this was associated with instances where, because of improper timing and/or adverse climatic conditions, the treatments were not very effective in promoting flowering the year applied.…”

The occurrence of flowering and fruiting on individual trees over 3 years and their effects on subsequent crown condition

“…Late frosts have been found to increase the cone crops of larch the following year (Wachter 1959(Wachter , 1962 and similar effects have been seen in Douglas fir (Ebell 1971). Analyses of the seed in such situations indicates that a high proportion is poorly developed suggesting a failure of the normal regulatory systems controlling flowering and fruit production.…”

“…Jackson and Sweet 1972;Puritch 1972;Philipson 1987), although with variable results. Girdling has been widely applied (Ebell 1971;Philipson 1985). However, the effects of girdling are not always readily apparent; Bonnet-Masimbert (1987) found no effect of girdling on the incidence of flowering in Norway spruce, although girdling in combination with gibberellin treatment reduced male flowering.…”

Salicylic acid and the flowering gene FLOWERING LOCUS T homolog are involved in poor-nutrition stress-induced flowering of Pharbitis nil

“…Non-photoperiodic flowering has been reported, and most of the factors responsible for flowering can be regarded as stresses. These factors include nitrogen deficiency (Tanaka et al, 1997), low-intensity light (Takimoto, 1973), drought (Monselise et al, 1981), root removal (Wada, 1974), girdling (Ebell, 1971) and mechanical stimulation (Metzger, 1995). Recent studies have shown that ultraviolet stress (Martínez et al, 2004) and nutrient stress (Kolá r and Senková , 2008) in Arabidopsis thaliana and lowintensity light stress in Perilla frutescens (Wada et al, unpublished data) also induce flowering.…”