EFFECTS OF PHOTOPERIOD AND TEMPERATURE ON THE GROWTH AND CYTOKININ CONTENT OF TWO POPULATIONS OF DACTYLIS GLOMERATA (COCKSFOOT)

Abstract

SUMMARY The effects of photoperiod (8 or 16 hr, SD or LD) and temperature (low or high, 8° or 20°C) on the growth and cytokinin content of Norwegian and Portuguese populations of Dactylis glomerata (Cocksfoot) were investigated. In general, conditions which promote active leaf growth (LD or high temperature) of plants of the Norwegian population tend to result in lower levels of cytokinin bases and/or nucleosides and in higher levels of ‘nucleotide’ cytokinins than conditions which lead to reduced growth rate (SD or low temperature). In some ‘transfer’ experiments the changes in hormone levels preceded detectable changes in growth rate. Cytokinins which behaved similarly to zeatin and zeatin riboside on Sephadex LH 20 columns were detected. The lack of response to application of exogenous zeatin or 6‐benzylaminopurine, together with the data on endogenous cytokinins, suggests that the level of cytokinin bases and nucleosides was not limiting the growth rate of the Norwegian population in SD at 8°C. However, if ‘nucleotide’ cytokinins are significant for growth rate under unfavourable conditions then this class of hormone may be involved in the responses to day length and temperature.

Effects of temperature and photoperiod on postponing bermudagrass (Cynodon dactylon [L.] Pers.) turf dormancy

“…Field experiment confirmed these results as well. Some reports have shown that prolonging photoperiod can increase carbohydrate contents in tissues (Boller and Nosberger, 1983;Hay and Pederson, 1986;Menhenett and Warening, 1977;Solhaug, 1991). Sucrose, starch and reserved carbohydrates are substantial in crown and stolons; soluble sugars such as sucrose are acting on preservation of proteins .…”

Effects of Extended Daylength on Shoot Growth and Carbohydrate Metabolism for Creeping Bentgrass Exposed to Heat Stress

“…Extended light duration delayed the decline in photosynthetic rate and chlorophyll content associated with foliar senescence in woody species (Rosenthal and Camm, 1997). Some studies reported increases in carbohydrate content with longer light duration (Boller and Nosberger, 1983;Hay and Pedersen, 1986;Menhenett and Wareing, 1977;Solhaug, 1991;Wang et al, 1997Wang et al, , 1998. Others found that light duration had no effects on carbohydrate production per day, but increased the amount of sucrose translocated out of leaves to roots (Logendra and Janes, 1992;Sicher et al, 1982).…”

Endogenous Cytokinin Levels and Growth Responses to Extended Photoperiods for Creeping Bentgrass under Heat Stress

“…Changes in photoperiod have been reported to control the synthesis of ZR‐5′‐monophosphate in leaves rather than cytokinin degradation (Machackova et al, 1996). Menhenett and Wareing (1977) reported that increasing daylength tended to reduce levels of cytokinin bases and/or nucleosides, but increased levels of nucleotide cytokinins for Dactylis glomerata L. Hebbar et al (1994) reported that zeatin and dihydrozeatin were the predominant cytokinins under long‐day conditions in carrots ( Daucus carota L.). In Sinapis alba , Lejeune et al (1994) found that isopentenyl adenine‐type (iP‐type; chemical definition???)…”

“…T emperature and daylength are two main factors controlling leaf initiation and growth, especially following defoliation or mowing (Menhenett and Wareing, 1977). Cattani and Struik (2001) reported that under favorable temperature conditions, increasing the photoperiod from 8 to 16 h daily increased tiller density, number of stolons and green leaves, and shoot dry weight in creeping bentgrass.…”