The Action of Some Cytokinins on the Rest‐period and the Content of Acid Growth‐inhibiting Substances in Potato

Abstract

Apical sections of resting potato tuber.s of the varietj' Majestic, -whicb is for a loug rest-period, -were treated for 6 and 24 bours -with water or witb the cytokiuius kinetiu or zeatiu. The cytokiuiu-treatment breaks the rest-period very rapidty. Ttie buds begiu to sprout already after 2-3 days. The content of acid inhibitors (the (} inhibitor) iu extracts of the peelings from cytokiuiu-treated sections is much lower than iu similar extracts froui water-treated, resting sections. Alreadv 6 hours after the beginning of tbe treatment, differences iu iubibitor content can be demonstrated.

Regulation of potato tuber sprouting

“…Even though bud break occurred in these tubers and petite sprouts were formed, they failed to develop further. These results support earlier findings that CK plays an essential role in the control of dormancy and sprouting (Hemberg 1970;Turnbull and Hanke 1985a;Suttle 2001Suttle , 2008. Suttle (2008) reported that synthetic phenylurea and nitroguanidine CKs were more effective in dormancy termination than the naturally occurring zeatin species because they escape inactivation by endogenous CKX.…”

Growth responses of potato (Solanum tuberosum) grown in a hot tropical lowland to applied paclobutrazol: 2. Tuber attributes

“…Dogonadze et al (2000) observed that exogenous GA 3 treatment promoted tuber sprouting by enhancing RNA and DNA synthesis and Hemberg (1970) reported an inhibitory effect of ABA to tuber sprouting through inhibited RNA and DNA synthesis. The regulatory effects of GA and ABA on RNA and DNA synthesis are probably the major contributors to delayed sprouting (Shik & Rappaport 1970).…”

“…In addition, GA accumulation in tuber tissue can specifically impede starch accumulation (Booth & Lovell 1972;Paiva et al 1983;Vreugdenhil & Sergeeva 1999), inhibit the accumulation of patatin and other tuber specific proteins (Hannapel et al 1985;Vreugdenhil & Sergeeva 1999) and, in combination with other inhibitors, regulate potato tuber dormancy (Hemberg 1970).…”

Reactivation of Meristem Activity and Sprout Growth in Potato Tubers Require Both Cytokinin and Gibberellin

“…These studies also revealed an increasing sensitivity to the phytohormone during postharvest storage, with tubers being insensitive immediately after harvest and for a period thereafter (Hemberg, 1970;Turnbull and Hanke, 1985a;Suttle, 1998a;Suttle and Banowetz, 2000). In a more recent study, Suttle (2008) showed that synthetic CKs such as N-2-(chloro-4-pyridyl)-N#-phenylurea and 1-(a-ethylbenzyl)-3-nitroguanidine are more effective in dormancy termination than the natural zeatin, probably because they escape degradation by CKX, but they did not eliminate the initial resistance period.…”

“…Early studies by Hemberg (1970) showed that both natural and synthetic CKs can rapidly induce sprouting in dormant tubers. Bioassays suggested an increase of endogenous CK levels before dormancy release, especially in the apical and lateral buds and the tissue surrounding them (Engelbrecht and Bielinska-Czarnecka, 1972;Van Staden and Dimalla, 1978).…”