"The evidence presented here that anthocyanins protect senescing red-osier dogwood leaves from excess light is based on laboratory studies in which we were able to impose on red- and yellow-senescing leaves identical treatments of high light intensity. We based our light treatments on the maximum PPFDs that a red-senescing leaf might experience under natural conditions. Yellow-senescing leaves are those that occur in more shaded microsites, and thus they would not normally experience these PPFDs (see “Materials and Methods”). The absence of any difference in maximum PSII photon efficiency of dark-adapted between red- and yellow-senescing leaves is consistent with the idea that yellow-senescing leaves do not experience high PPFDs at sufficient duration (i.e. sun flecks are short lived) to cause photodamage under natural conditions (Table
I). If PPFDs are sufficiently high and prolonged, then anthocyanin accumulation is induced. Red-osier dogwood appears to show a facultative anthocyanin production. Manipulations of red-osier dogwood canopies (i.e. removal of shading branches) in early autumn to expose leaves normally senescing yellow resulted in anthocyanin accumulation. Furthermore, leaves flipped in their orientation accumulate anthocyanins in the spongy mesophyll cells, whereas the palisade mesophyll remains anthocyanin-less during senescence. This indicates that anthocyanin accumulation is not developmentally programmed at the leaf or leaf tissue level. Anthocyanin production and expression of key regulatory enzymes are known to be up-regulated by high light intensity or treatments that limit photochemical utilization of excitation energy (
Christie et al., 1994;
Nooden et al., 1996;
Chalker-Scott, 1999), suggesting that anthocyanins play a physiological role in coping with excess light.
A need for protecting chloroplasts from excess light absorption during autumn senescence at first seems counterintuitive. Given that light interception declines during autumn and thylakoid membranes already contain xanthophyll pigments to dissipate excess light energy (
Demmig-Adams and Adams, 1992;
Horton et al., 1996), why should an additional mechanism for reducing light captured by chloroplasts be deployed? One hypothesis is that the metabolic changes that occur during leaf senescence increase the susceptibility of light-induced oxidative damage to leaf cells (
Nooden et al., 1996;
Merzlyack and Hendry, 1994).
Leaf senescence is a programmed transformation of leaf metabolism and ultrastructure whose functional significance is best understood from the perspective of nutrient salvage (
Smart 1994;
Killingbeck, 1996;
Buchanan-Wollaston, 1997;
Quirino et al., 2000). This is paramount in plastids where as much as 90% of the nitrogen recycled from senescing leaves comes from the degradation of stroma proteins and thylakoid membranes (
Evans, 1983;
Killingbeck, 1996;
Thomas, 1997;
Matile et al., 1999). However, before nitrogen can be mobilized, chlorophyll molecules must be unbound from their associated proteins and enzymatically degraded (
Hinder et al., 1996;
Thomas, 1997;
Matile et al., 1999;
Matile, 2000). Chlorophyll breakdown apparently does not result in the release of nutrients that are resorbed by the leaf; instead, chlorophyll is catabolized and the degradation products stored in the vacuole using a detoxification pathway shared with xenobiotic compounds (
Peisker et al., 1990;
Hinder et al., 1996;
Thomas, 1997;
Matile et al., 1999;
Matile, 2000). This special handling reflects the high phototoxicity of unbound chlorophyll and its derivatives, which readily produce highly reactive singlet oxygen in the presence of light and oxygen (
Merzlyack and Hendry, 1994;
Thomas, 1997;
Marder et al., 1998;
Matile et al., 1999). If free chlorophyll is not catabolized or protected from light, the uncontrolled generation of singlet oxygen could jeopardize the viability of senescing leaf cells through photo-oxidative damage (such as per-oxidation of membrane lipids;
Merzlyack and Hendry, 1994;
Asada, 1999). Because autumn senescence involves the rapid liberation of the entire pool of chlorophyll (
Sanger, 1971;
Matile, 2000), it presents a substantial opportunity for oxidative damage that may reduce the efficiency of nutrient recovery from senescing leaves. By acting as an optical screen that reduces the light capture of senescing chloroplasts, anthocyanins provide an additional degree of photoprotection during the dismantling of the photosynthetic apparatus"
When your plants not healthy, it will produce anthocyanin to protect itself. Also will help your plants die faster and more efficiently. Faster flowering is not neccessarily a good thing. A longer flower and greener plant will yield more total mass yet not as high content in oil. Im saying theres good chance here that total oil content will be the same. However they will be more viney and harder to manage due to stem elongation. From a commercial pov the IMO the v2 would be better, more mass to sell but for quality if you want to mess around with screens and stuff the rspec may be better. I already own several of both so im taking a tiered approach with doing most of my flowering under the V2 and then finishing them under the rspec. Before your fan leaves start to yellow around week 5 of flower, i would switch them under an rspec to optimize the breakdown and speed up the process. Incorporating UV i to the rspec would be the best option to really increase these effects.
