Dormancy and seasonal changes of plant growth regulators in hazel buds

Abstract

Levels of indole‐3‐acetic acid (IAA), abscisic acid (ABA) and total phenolic compounds have been determined in hazel (Corylus avellana L. cv. Negreta) buds. IAA and ABA were quantified by flame ionization detector gas‐chromatography, and the phenolic content determined by a colorimetric technique. The highest level of free ABA occurs in autumn, approximately at the onset of winter dormancy, and it is lowest just before bud burst; suggesting that ABA plays an important role in the induction and maintenance of winter dormancy. The opposite result was obtained for IAA; the level of this regulator was low in autumn and showed a sharp increase just before budbreak. With respect to phenols, an apparent correlation can be observed between them and ABA in at least some of the fractions studied (acid and residual), so that they may enhance the inhibitory effect of ABA. The IAA/inhibitor balance showed a clear correlation with dormancy. In autumn (dormant buds), this balance is in favour of the inhibitors while the balance shifts towards IAA at the end of winter.

The role of air temperature in determining dormancy release and flowering ofCorylus avellana L.

“…If outdoor temperature is high, the value of 220 GDH~ will be obtained in only 10 days, and pollination will begin in the last days of December, as in 1983, but if temperature remains too low for growth (i.e. below 4.5~ the heat accumulation requires up to 30-35 days and the Cotyhts-pollen season will start at the end of January, as in the winters of 1986-87, 1988-89 and 1989. In the Perugian area, after the break of dormancy in mid-December, the outdoor mean temperature is normally above 4.5~ so the heat requirement is met quickly and the main period of pollination for hazel begins in January (Fig.…”

8. The role of plant growth regulators in dormancy in forest trees

“…Using fluorescence spectrophotometer and GLC to examine leaf extracts of P . Rodriguez and Sanchez-Tames (85), also using GLC with flame ionization detector, reported that the lowest level of IAA in Caryllus avellana occurred in fall and that it increased sharply just before bud break . DeYoe and Zaerr (19) also found low levels of IAA in Pseudotsuga menziesii during dormancy using GLC with flame ionization detection followed by GLC-MS .…”

“…Most comprehensive studies (85) of the dormancy in tree species utilize seedlings because working with mature trees is difficult . however, seedlings of virtually all tree species have different growth patterns from mature trees (31,51) .…”

Phenols and bud dormancy

“…In previous work (Codignola, MafFei & Fieschi, 1988) it was observed that the inception and maintenance of dormancy in F. sylvatica buds was not correlated to the total phenolic pool in leaf primordia while some kind of correlation seems to occur in bud scales. Since the previous research dealing with phenols and bud dormancy (Erez & Lavee, 1968;El Mansy & Walker, 1969;Sarapuu, 1970;Melin et al, 1974;Thakur, 1977;Mandahar, Gulati & Nath, 1980;Codignola ct al., 1982;MafTei, Codignola & Gallino, 1982;Gallino, Codignola & .MafTei, 1982;Rodriguez & Sanchez-Tames, 1986) only took in to consideration whole buds, it was not possible to make a direct comparison with our previous work (Codignola et al, 1988).…”

“…Since the previous research dealing with phenols and bud dormancy (Erez & Lavee, 1968;El Mansy & Walker, 1969;Sarapuu, 1970;Melin et al, 1974;Thakur, 1977;Mandahar, Gulati & Nath, 1980;Codignola ct al., 1982;MafTei, Codignola & Gallino, 1982;Gallino, Codignola & .MafTei, 1982;Rodriguez & Sanchez-Tames, 1986) only took in to consideration whole buds, it was not possible to make a direct comparison with our previous work (Codignola et al, 1988).…”