So p. aquatica is much better source of DMT through reported levels are small 0.1%. Are there any conditions that can increase DMT levels in phalaris grass? Only leaves contain DMT and is content of DMT calculated in dry of fresh leaves?
In Festi and Samorini paper I found that stressing phalaris plants can help produce more DMT or 5-MeO-DMT:
"Plants growing after a moisture stress may contain up to three times the concentration ofalkaloids found in regularly watered samples. The highest increase of the tryptamine alkaloids is shown at the first reduction of the leaves turgor: the most affected alkaloid seems to be the 5-MeO-DMT. Moreover, the first regrowth of the stressed plants contains more DMT and less 5-MeO-DMTthan the regrowth of the non-stressed ones [Marten, 1981; Williams, 1972; cf. Ball& Hoveland,1978]. The influence of frost is very similar, even though in this case the DMT appears to be the most affected indole alkaloid. The highest increase for an exposure to -2°C during the night, isfound in seedling of P. aquatica growing at high nitrogen level in the soil and with day/night temperature of respectively 21 and 16 °C [Williams, 1972]. There is, in conclusion, a little increaseof the alkaloids in plants growing at high compared to low temperature but in general the effects ofthis factor are weak [Frelich, 1973; Frelich & Marten, 1972; Marten, 1981; Marten& Frelicr1977; Moore etal, 1966; 1967;
So lack of water, high nitrogen soil and frost seem to increase DMT.