DESARROLLO DEL SECTOR TURÍSTICO

0 10 100 1000 10000 100000

Ferulic Acid Gallic Acid Juglone

p-Coumaric Acid

Figure 3.12. Lactuca sativa ‘Inferno’ seedling length 11 days after initial soil treatment in response to increasing rates of plant

compounds. Concentration is on a logarithmic scale. +Treatment seedling length was

significantly greater than the herbicide control (p < .025). #Treatment was significantly less than the water control. *Treatment seedling length was significantly less than the herbicide control (p < .025). The herbicide control had

significantly shorter seedlings than the water control (p < .0001). Error bars are ±1 SEM.

+ + + # # # # # # # #* #*

completely inhibited L. sativa growth and so we excluded these zero seedling length results, as well. We could not fit juglone seedling length curves for M. parviflora, M. officinalis, or S. vulgaris due to dormancy, and/or because the compound completely inhibited seedling length on day 11 at all rates (which was the case for both M. parviflora and M. officinalis, see APPENDIX F.).

Curve fits, at times, violated model assumptions and/or model fit criteria so we suggest exercising some caution when interpreting model predictions. Adjusted R2

values were 0.93 or above for all fitted curves except p-Coumaric acid’s P. annua seedling length fit (0.87) (Tables 3.9. and 3.10a.).

We considered overlapping EC confidence intervals to surround EC values that were not significantly different, and non-overlapping EC confidence intervals to surround significantly different EC values. The EC50 and EC75 values were significantly lower for

juglone than any of the other plant compounds (Tables 3.9. and 3.10a.). Gallic acid required the greatest concentrations to achieve half-maximal and three-quarters maximal responses. Plant compounds for the L. sativa assays were in the following order of greatest to lowest phytotoxicity: juglone > p-Coumaric acid > ferulic acid > gallic acid.

Generally, L. sativa seedling length EC50 values associated with each plant

compound were lower than the weed seedling length EC50 values associated with the

weed species seedling length data we were able to fit curves to. However, S. vuglaris in ferulic acid-treated wells had a significantly lower EC50 value than L. sativa in ferulic

acid-treated wells. Even so, S. vulgaris and L. sativa did not have significantly different ferulic acid EC75 values.

The cost to inhibit L. sativa seedling length in soil by 50% on a per acre basis (at a depth equivalent to that of the soil in 24-well plate wells) was in the following order of least to most expensive: gallic acid < juglone < p-Coumaric acid < ferulic acid (Table 3.9.). The order of least to most expensive compound to inhibit L. sativa seedling length by 75% in soil on a per acre basis was nearly identical, with p-Coumaric acid being less expensive than juglone at this higher rate. Prices of individual plant compounds may decline if supply increases due to an increase in demand.

Analyses of variance followed by Dunnet’s tests compared the mean seedling length of the water or herbicide controls to the mean seedling length of treatments (Table 3.8.). In L. sativa assays, all treatments had significantly shorter mean seedling lengths than the water control except for the low and medium-low rates of p-Coumaric

acid (Figure. 3.12.). These two rates were also the only two plant compound treatments to have significantly longer L. sativa seedling lengths than the herbicide control. The medium-low and high rate ferulic acid treatments had significantly shorter L. sativa

Lactuca sativa ‘Inferno’

Malva parviflora

Poa

annua Poa annua

Senecio vulgaris Compound All Compounds Gallic Acid Juglone p-Coumaric acid Ferulic Acid p-values ANOVA < .0001 < .0001 < .0001 < .0001 < .0001 Block .1966 .0391 .2903 .8399 .9447 Contamination (Day 11) .8633 .0006 - - .8317 Treatment < .0001 < .0001 < .0001 < .0001 < .0001 Table 3.8. Analysis of variance (response variable: seedling length) for Lactuca sativa ‘Inferno’, Malva parviflora, Poa annua, or Senecio vulgaris growing in soil amended with plant compounds. The “Treatment” factor levels were the four compounds at each rate (low, medium-low, medium-high, and high).

seedling lengths than the herbicide control. In the weed assays, at least one plant compound treatment had significantly shorter mean seedling lengths than the water control except for gallic acid (Figure 3.13.). In gallic acid M. parviflora assays the only treatment that did not have statistically greater seedling lengths than the herbicide control was the high rate. No treatment, in any of the weed assay data we fit curves to, inhibited seedling length to a statistically greater degree than the herbicide control.

Compound Regression Adj. R2 Hill- slope EC50 Kg/ acre Cost ($/acre) EC75 Kg/ acre Cost ($/acre)

UCL Mean LCL UCL Mean LCL

Ferulic Acid Logistic 1P 0.96 -1.94 570 644 728 12.19 100,436 997 1136 1275 21.49 177,100 Gallic Acid Logistic 1P 0.95 -1.13 1342 1584 1870 29.98 21,676 3521 4192 4914 79.34 57,360

Juglone Logistic 1P 0.99 -1.71 120 129 138 2.43 48,684 228 245 261 4.63 92,663 p-Coumaric Acid Gompertz 3P 0.98 -7.53 561 616 666 11.65 69,898 708 761 805 14.40 86,399

Species Compound Regression

Adj. R2

Hillslope

EC50 EC75

UCL LCL UCL LCL

Senecio vulgaris Ferulic Acid Logistic 1P 0.93 -0.90 252 316 397 844 1075 1337 Malva parviflora Gallic Acid Logistic 3P 0.94 -1.55 5632 6195 6764 11406 12614 14038

Poa annua Juglone Logistic 1P 0.96 -1.70 189 215 246 481 551 627 Poa annua p-Coumaric Acid Logistic 1P 0.87 -2.05 1313 1663 2106 2170 2843 3523

Species Compound EC50 EC75 Kg/acre Cost ($/acre) Kg/acre Cost ($/acre) Senecio vulgaris Ferulic Acid 5.98 49,296 20.34 167,620 Malva parviflora Gallic Acid 117 84,773 239 172,617 Poa annua Juglone 4.08 81,553 10.43 208,571 Poa annua p-Coumaric Acid 31.48 188,880 53.80 322,797

Table 3.10a. Regression hillslope, and EC50 and EC75 values (parts per million by weight) for several weed species (Malva parviflora, Poa annua, and Senecio vulgaris) growing in soil amended with ferulic acid, gallic acid, juglone, or p-Coumaric acid.

Table 3.9. Regression hillslope, adjusted R2

, and EC50 and EC75 values (parts per million by weight), application rate (Kg/acre), and cost (USD) for Lactuca sativa ‘Inferno’ growing in soil amended with ferulic acid, gallic acid, juglone, or p-Coumaric acid.

Table 3.10b. Plant compound application rates (Kg/acre) and costs (USD) to control weeds in strawberry field soil.

0 1 2 3 4 5 0 10 20 30 40 50 60 70 Concentration(Log[ppmw]) Poa annua Seedling Length (mm)