Photodynamic Herbicides - Chlorophyll Biosynthesis and Technological Applications - page 385

Table 17.4 Effect of δ -aminolevulinic acid (ALA) sprays on greenhouse-grown velvetleaf and

tall morningglory

Percent injury
VL MG

Location Treatment Rate (g/acre) (%)

Greenhouse 2.9

Plants were germinated in vermiculite in glass containers 7.5-cm deep and 9 cm in diameter under
a 14-h light/10 h dark photoperiod. Light intensity (metal halide) was about 211 W m 2 . After
10 days VL (velvetleaf) or 20 days MG (morningglory) of growth, the seedlings were sprayed with
2 lbs. Per acre of ALA. ALA was dissolved in a solution made up of 2.25 % acetone, 0.25 %
Sylgard, 1.0 % Tween -80, 9.00 % polyethylene glycol 600, 6 % soybean oil, 79.50 % water.
Photodynamic damage was assessed 10 days after spraying. Values are means of three replications

ALA 900 98.29 2.9 97.00

standard deviation VL velvetleaf, MG Morningglory (Reproduced from Kulur 1996 )

Table 17.5 Comparison of the effects of ALA sprays, with and without modulators, and
acifluorfen, in a randomized plot design, on soybean and several weed species under field
conditions

Percent injury
Soybean

VL GF TMG JW WM

Location (%)

Field ALA 900 24 71 56 53 58 50
Dpy 300 7 30 25 23 23 18
ALA + Dpy 900 + 300 21 65 52 43 55 55
Oph 300 16 51 18 20 28 30
ALA + Oph 900 + 300 30 79 63 66 73 78
Acifluorfen 171 47 96 92 97 99 99
Control 0 0 0 0 0 0 0
LSD (0.05) - 7 14 30 19 17 20
Values are means of three replicates. Photodynamic injury was evaluated 17 days after spraying.
Application date

Treatment Rate (g/acre)

151 l/acre. ALA
δ -aminolevulinic acid, Dpy 2,2 0 -dipyridyl, Oph 1,10-orthophenanthroline, VL velvetleaf, GF
giant foxtail, TMG tall morningglory, JW jimsonweed, WM wild mustard, LSD least significant
difference (Adapted from C. A. Rebeiz and R. Liebel, unpublished). Other conditions are as in
Table 17.4

¼ 07/08/87. Plot size ¼ 5 18 ft. Spray volume ¼

ALA detected in treated leaves of all ages were not significantly different from one
another (Table 17.6 , Fig. 17.4 ). These results suggested that under our growth
conditions, leaf age had no bearings on ALA penetration to active sites of tetrapyr-
role metabolism.
Further insight into the metabolic fate of ALA was derived from an examination
of tetrapyrrole accumulation. ALA-treated plants accumulated significantly higher
amounts of tetrapyrroles than untreated ones (Table 17.6 , Fig. 17.4 ). The
accumulated tetrapyrroles consisted mainly of Pchlide a . The accumulation of
Pchlide a was age-dependent and the amount of tetrapyrroles accumulated by
10 and 15-day old plants was higher than in 20-day old plants (Table 17.6 ,
Fig. 17.4 ). Together with ALA content (see above), these results suggested that