KAOLIN PARTICLE CLAY FILM EFFECTS ON ...walnutresearch.ucdavis.edu/2010/2010_269.pdfKaolin particle...

KAOLIN PARTICLE CLAY FILM EFFECTS ON PHYSIOLOGY, QUALITY, AND PRODUCTIVITY IN TULARE AND HOWARD WALNUT Carolyn DeBuse, Janine Hasey, Kathy Kelley Anderson, Sam Metcalf, Loreto Contador, Bill Stewart, Michael Glenn, and Bruce Lampinen ABSTRACT Three studies were conducted to look at impacts of kaolin particle clay film (Surround®WP; TKI NovaSource, Phoenix, AZ 15627) on quality and yield in walnut. The first study was set up in an 11 year old Tulare walnut orchard in Solano County, the second in a 10 year old Howard orchard in Yuba County and the third in a 9 year old Tulare orchard in Yuba County. In these three trials, Surround® did not have any beneficial impact on midday canopy light interception, yield or yield per unit light intercepted. Surround® had a negative impact on canopy light interception and yield in the Solano County orchard which was near 90 percent midday canopy light interception, likely due to the Surround® coverage being concentrated on lower shaded leaves. Based on these results, it would not be recommended to apply Surround® with a ground based sprayer in orchards with midday canopy light interception above 80%. Surround® treated trees tended to have cooler leaf temperatures, particularly at midday but this did not appear to produce any economic benefits in terms of productivity or quality in the present studies. BACKGROUND AND OBJECTIVES Kaolin particle clay film has been shown to increase fruit size, fruit color and yield in various horticultural species with the results being dependent on the environment, species and time of application (Glenn and Puterka, 2005). Earlier work on walnut showed that a kaolin application resulted in leaf temperatures that were 1-3°C cooler (Rosati et.al, 2006), increased reflectance from the top of the canopy, and decreased photosynthetically active radiation (PAR) reaching individual leaves but led to improved light distribution in the lower canopy (Rosati et.al., 2007) The overall conclusion was that canopy photosynthesis could potentially be increased despite the decrease in light reaching individual leaves due to the impacts of Surround® on lowering canopy temperature and redistributing light in the lower canopy. Another possible impact of kaolin could be on nut quality. Previous work has shown that kaolin can lead to lower nut temperatures and this can potentially prevent sunburn damage in walnut (Lampinen et.al, 2006). Finally, it is possible that shoot growth or leaf expansion could be greater due to more accumulated photosynthesis resulting from cooler leaf temperatures. We plan to investigate this possibility using midday light interception measurements. The present studies were designed to study the impacts of Surround® on canopy temperature, water relations, yield and quality in walnut.

California Walnut Board 269 Walnut Research Reports 2010

PROCEDURES Three studies were set up to look at impacts of kaolin particle clay film (Surround® WP; TKI NovaSource, Phoenix, AZ 15627) on quality and yield in walnut. The first site was an 11-year- old Tulare orchard in Solano County. The second site was a 10 year old Howard orchard in Yuba County and the third was a 9 year old Tulare orchard in Yuba County. Solano County site The first study site is an approximately 11 year old Tulare on Paradox rootstock walnut orchard located in Solano County near the town of Winters. Tree spacing was 28’ x 28’ in a square design. 2009 An aerial image of the site showing the Surround® applications (white strips) is shown on the following page. Surround® was applied on June 14, 2009 and again on June 29, 2009 at a rate of 100 lbs per acre plus 7 oz ProNatural Speader in 200 gallons of water with an air blast sprayer.

Photo 1. Aerial image of study orchard taken in September 2009.


In 2009, midday stem water potential was measured on June 16, June 17, Aug. 4, Aug. 12, Aug. 18, and Sept. 2 on 24 trees in each treatment. Midday canopy light interception was measured with a handheld light bar (Decagon Devices, Pullman, WA 99163) on June 3, 2009 and on June 17, 2009. Midday canopy light interception was also measured with a mobile platform mounted lightbar on June 2 (before first Surround® application), June 17 (after first Surround® application) and July 13 (after second Surround® application). On July 13, a thermal imaging camera (Flir Thermovision A40; Flir Systems, Wilsonville, OR) was used to image individual trees in the trial. The south-east-upper-sunlit canopy was imaged in the late morning measurements and the south-west-upper-sunlit canopy was imaged in the afternoon measurement period. Twenty five trees were chosen for measurement in block I of the control and kaolin treatments. Stem water potential was measured on each tree during the morning and afternoon imaging periods. The maximum, average and minimum temperature were determined from each image and these were used to compare to midday stem water potential to see if there was a relationship between water potential and leaf temperatures. Temperature and relative humidity dataloggers (Hobo Pro v2; Onset Computer, Pocasset, MA 02559-3450) were installed in the lower shaded canopies of one tree in each replication (total of 6 dataloggers in each treatment). The dataloggers were set to record a data point every 5 minutes. On October 7, 2009 the trial was harvested using the growers’ harvester and bank out wagons. The rough weight from each row was recorded from drive on scales. Samples for hulling, drying and quality were taken to allow the adjustment of field rough weights to the industry standard in-shell dry weights. Quality samples were evaluated by the authors as well by Diamond Foods, Inc. 2010 Surround® was applied three times in 2010 (June 1, June 15, and July 7) at a rate of 100 lbs per acre plus 7 oz ProNatural Speader in 200 gallons of water with an air blast sprayer. In 2010, midday stem water potential was measured on June 1, June 14, June 15, June 21, July 7, July 16, July 29, and Aug. 20 on 24 trees in each treatment. Midday canopy light interception was measured with a mobile platform mounted lightbar on August 20 and again on October 20. Temperature and relative humidity dataloggers (Hobo Pro v2; Onset Computer, Pocasset, MA 02559-3450) were installed in the lower shaded canopies of one tree in each replication (total of 6 dataloggers in each treatment). The dataloggers were set to record a data point every 5 minutes. Four additional dataloggers were also placed in two replications in the poor growth part of the orchard in 2010. On October 14, 2010 the trial was harvested using the growers’ harvester and bank out wagons. The rough weight from each row was recorded from drive on scales. Samples for hulling, drying and quality were taken to allow the adjustment of field rough weights to the industry standard in-shell dry weights. Quality samples were evaluated by the authors as well by Diamond Foods, Inc. Yuba County sites There were two study sites in 2009: 1) a 67.5 acre Howard orchard planted in 1999 and 2) a 60 acre Tulare orchard planted in 2000.


Yuba County Site #1 (Howard) - Spacing is 18’ x 24’ in a hedgerow Howard planting. Surround® applied aerially on June 25, 2009 and again on July 1, 2009 early in the morning was compared to an unsprayed control. Treatments were an aerial Surround® spray, a ground Surround® spray and an unsprayed control. There were six treatment replications in a randomized complete block design with each plot row separated by 3 buffer rows. The plot rows were on the same phase of the 4-year hedging rotation. One ground application of Surround® at 50 lbs per acre in 100 gallons of water plus 4 oz/100 of ProSilicon 100 surfactant was made with a Nelson Hardie C225 sprayer travelling ~3.75 mph on June 25th. Aerial applications of Surround® at 30 lbs per acre in 30 gallons of water plus 4 oz/100 of ProSilicon 100 surfactant were made with a Huey helicopter at 60 lbs pressure, travelling 45 mph with 45 spinner D8 nozzles over the middle row. Wind speed was 7.1 mph on June 25th and 4.6 mph on July 1st. Midday canopy light interception was measured with the mobile platform light bar in the middle row of each replication at midday on 7/14/10. On this same day, thermal imaging was also done on 10 trees in each treatment using the methods described under the Solano County methods. Tree counts down each row were also done on this date. Plots were harvested and subsamples taken for drying and quality on October 8, 2009 using same methods as described for the Solano County site. Yuba County Site #2 (Tulare) - Spacing is 18’ x 24’ in a hedgerow Tulare planting. Surround® applied aerially on June 25, 2009 and again on July 1, 2009 early in the morning was compared to an unsprayed control. There were four treatment replications with each plot consisting of three rows in a randomized complete block design. Yield and nut quality data were only taken from the center rows that were on the same phase of the 4- year hedging rotation. Aerial applications of Surround® at 30 lbs per acre in 30 gallons of water plus 4 oz/100 of ProSilicon 100 surfactant were made with a Huey helicopter at 60 lbs pressure, travelling 45 mph with 45 spinner D8 nozzles over the middle row. Wind speed was 7.1 mph on June 25th and 4.6 mph on July 1st. Midday canopy light interception was measured on the middle row of each replication on 9/24/09. Plots were harvested and subsamples were taken on September 21, 2009 using similar methods as those described for the Solano County site. RESULTS AND DISCUSSION Solano County Site 2009 Midday stem water potentials were similar for the control and kaolin particle clay film treated treatments on most dates (Table 1). The only exception was on Aug. 4, 2009, when the average midday stem water potentials for the kaolin treated trees in the good growth area were significantly lower (more stressed) compared to the control treatment trees (Table 1). On this same date, the kaolin treated trees had similar canopy temperatures compared to the untreated treatment trees (Fig.3). The lower midday stem water potentials may have resulted from the lower leaf temperatures in the Surround® treated treatment which would allow them to keep their stomata open longer at midday which could then result in increased water use and eventually lower midday stem water potentials. This is consistent with reports from Glenn et.al, 2003 who found that in apple, whole-tree carbon assimilation was increased by kaolin applications under conditions of excessive air temperature but water use efficiency was decreased. Midday stem water potentials in the poor growth area of the orchard tended to run about 1 bar more stressed than in the good growth area of the orchard (Table 1).


Midday canopy light interception gradually increased from June 2 to July 13 and the change was similar for the untreated control and the Surround® treatments in 2009 (Table 2) suggesting that the Surround® had little effect on overall midday canopy light interception. This lack of treatment impact on midday canopy light interception was similar in the good and poor growth parts of the orchard (Fig. 2). Leaf temperature was measured with a Flir thermal imaging camera. Our assumption was that the hottest leaves would be those that are most nearly perpendicular to the sun. By using the maximum values we should be able to get the best indication of the impacts of water stress and kaolin on leaf temperature since it would minimize the effects of leaf angle. On July 13, 2009, maximum leaf temperatures tended to run cooler in the Surround® treated trees in both the morning and afternoon measurements but the differences tended to decrease with increasing water stress in the afternoon (Fig. 1). The differences were larger when the trees were less stressed and tended to disappear as midday stem water potentials reached about -5 to -6 bars in the afternoon (Fig. 1). Interior canopy temperatures tended to run slightly cooler at midday in the Surround® treated trees and the differences were sometimes significant, usually in mid-afternoon (Fig. 3). The only exception was on August 4, 2009 which was discussed earlier. In 2009, there were no significant treatment effects on nut weight or any quality characteristics (Table 3). Harvest weights were not used for analysis in 2009 due to problems with the scales used for harvest. However, since this is the first year of treatment imposition, there would not be expected to be any differences in number of nuts per tree. Therefore, relative nut weights would likely correlate with yield differences suggesting there were likely no yield differences. 2010 In 2010, midday stem water potentials tended to run near the fully watered baseline throughout the season and were similar for the control and Surround® treated trees on most dates (Table 1). On two dates, 6/15/10 and 7/07/10, the Surround® treated trees were significantly more stressed than the control trees (Table 1). This also happened on 8/4/09 (Table 1). In 2010, the trees in the poor growth part of the orchard (Table 1) ran about 2 bars more stressed than those in the good growth area of the orchard (as compared to one bar of difference in 2009). The seasonal average

Photo 2. Appearance of trees in good growth area for untreated control (left) and Surround® treated trees (right).


midday stem water potential was similar for untreated control and Surround® treated trees in both the good and poor growth areas of the orchard (Table 4). Midday canopy light interception was measured on Aug. 30 and Oct. 20 in 2010. For the untreated control in the good growth area, midday canopy light interception was similar on both dates (Table 4). However, the Surround® treatment in the good growth area had a significant decrease in midday canopy light interception from the first to second measurement date (Table 1). This corresponded to the visual appearance of the trees which lost a lot of lower canopy leaves as the summer progressed (Photo 2). In the poor growth area of the orchard, results were quite different. On both measurement dates, the Surround® treatment had numerically, though not statistically significantly higher light interception compared to the control. The differential leaf loss seen in the good growth part of the orchard for the Surround® versus control treatment was not seen in the poor growth part of the orchard (Table 4). Although light interception went down both for the control and Surround® treatments in the poor growth area, it went down more for the control treatment (Table 4). The decrease in midday canopy light interception in the poor growth part of the orchard was likely due to water stress that occurred after the last water potential measurement data on 8/20/10. Canopy temperatures tended to run hotter in the control treatment trees during afternoon in both the good and poor growth areas of the orchard (Fig. 4). Canopy temperatures were about 5 deg F warmer in the poor growth area of the orchard compared to the good growth area of the orchard (Fig. 4). Yields were significantly higher in the control treatment as compared to the Surround® treatment in the good growth part of the orchard (Table 4). This was likely due to the severe lower canopy leaf loss that occurred. The yield per unit light intercepted was also significantly lower in the Surround® treatment in the good growth area (Table 4). In the poor growth part of the orchard, yields were slightly, but not significantly higher for the Surround® treatment compared to the untreated control (Table 4). Yield per unit light intercepted were similar for the control and Surround® treatments in the poor growth area of the orchard (Table 4). There were no significant treatment related differences in nut quality in 2010, except that individual nut weight was significantly less in the Surround® treated treatment (Table 3). This was again likely due to the inability to size lower canopy nuts due to the large amount of leaf loss that occurred in late summer. Yuba County Site #1 (Howard) The application of Surround® was significantly lighter on both Yuba County orchards compared to the Solano County orchard. Neither aerial nor ground applied Surround® had any significant impacts on yield, midday canopy light interception, or yield per unit light intercepted (Table 5). The yield per unit light intercepted was near the upper limit of 0.05 tons per unit light intercepted based on our other work (Lampinen et.al, 2010). The only significant treatment effect on any quality characteristic was that the ground application treatment (applied one time) had a lower percentage of extra light nuts (Table 6). Yuba County Site #2 (Tulare) There were no significant treatment impacts on yield, midday canopy light interception, or yield per unit light intercepted (Table 7). Yields for this trial were significantly less than for the


Howard trial in Yuba County site #1 as were the yields per unit light intercepted (Table 7). There were no significant treatment effects on quality (Table 8). The normal method of accounting for missing trees in trials is to do a tree count, taking into account partial and totally missing trees when doing the final yield per acre estimates. In this trial, the traditional tree count was compared to the midday canopy light interception data collected with the mobile platform light bar (Fig. 4). The relationship between the two methods of estimating canopy cover was quite good suggesting that in the present trial, either method could be used to account for missing trees when doing yield studies. SUMMARY Although leaf and canopy temperatures tended to run cooler in the kaolin treated trees, this did not result in any significant differences in nut size or quality in either year at the Solano trial or in either of the trials in Yuba County. Overall, there were no significant improvements in midday canopy light interception, yield, or quality for any of the three trials. There was a negative impact of Surround® on canopy light interception and yield in the good growth part of the orchard in the Solano County trial in 2010. The defoliation that occurred in this orchard is likely due to several factors. First, the Surround® was applied at a higher rate than growers would apply. Secondly, the Surround® was applied with a ground based air-blast sprayer on an orchard that was at about 90 percent canopy cover versus 70 to 78 percent canopy cover on the other two trials. With a canopy cover of 90 percent, a large part of the Surround® that was applied with the ground based sprayer was deposited on lower shaded leaves. These leaves were likely near the point where they were becoming a net negative due to shading (i.e. the lower canopy was dying out). When the Surround® was applied, the leaves became a net negative (meaning their respiration and maintenance costs were greater than their net gain from photosynthesis) and the tree dropped them. Based on the results of this study, it would not be recommended to apply Surround® from a ground based sprayer in orchards that are above 80% midday canopy light interception. It is unlikely that these orchards would benefit from Surround® application but if it is applied to such orchards, it should probably be applied by air. At light interception levels below 70% or so, it is much less likely to see the leaf loss described here.


BIBILIOGRAPHY Glenn, D.M., A. Erez, G.J. Puterka, and P. Gundrum. 2003. Particle films affect carbon assimilation and yield in ‘Empire’ apple. J. Am. Soc. Hort. Sci. 138:356-362. Glenn, D. M. and G.J. Puterka. 2005. Particle Films: A New Technology for Agriculture. Hort. Rev. 31: 1-44. Lampinen, Bruce, Kathy Kelley Anderson, Sam Metcalf and Claudia Negrón. Effects of kaolin clay particle film on leaf temperature, nut temperature and sunburn susceptibility in walnut. 2006. Walnut Research Reports 2005. pp. 309-313. Lampinen, Bruce, Shrini Upadhyay, Vasu Udompetaikul, Greg Browne, David Slaughter, Samuel Metcalf, Bob Beede, Carolyn DeBuse, Janet Caprille, Bill Coates, John Edstrom, Rachel Elkins, Joe Grant, Janine Hasey, Kathy Kelley and Bill Krueger. 2010. Refining the relationship between canopy light interception and yield in walnut. Walnut Research Reports 2009. California Walnut Board, Folsom, CA 95630. Pp. 103-108. Rosati, A., S.G. Metcalf, R.P. Buchner, A. Fulton, and B.D. Lampinen. 2006. Physiological effects of kaolin applications in well-irrigated and water-stressed walnut and almond trees. Ann. Bot. 98: 267-275. Rosati, A., S.G. Metcalf, R.P. Buchner, A. Fulton, and B.D. Lampinen. 2007. Effects of kaolin application on light absorption and distribution, radiation use efficiency and photosynthesis of almond and walnut canopies. Ann. Bot. 99: 255-263. ACKNOWLEDGEMENTS We would like to thank Dan Martinez of Martinez Orchards, Craig McNamara, Joe Conant of the Whitney Warren Ranch, the California Walnut Board, Diamond Foods Inc., and Kurt Volker of TKI Novasource for support for this project.


Table 1. Solano County site. Midday stem water potential for the control and kaolin particle clay film treatments. There were a total of 24 trees measured in each treatment on each sampling date. 2009

Midday stem water potential (bars) Treatment

6/17

/09

6/

18/0

9

8/

4/09

8/

12/0

9

8/18

/09

9/2

/09

Good growth area Untreated control -3.3 a -2.9 a -5.9 a -5.5 a -6.0 a -5.6 a Kaolin sprayed -3.3 a -3.1 a -6.8 b -5.8 a -6.6 b -5.8 a Fully watered baseline -4.1 -4.6 -4.6 -5.6 -4.4 -3.9 Poor growth area Untreated control -4.2 a -4.5 a -6.6 a -7.0 a -5.8 a Kaolin sprayed -4.4 a -4.7 a -6.9 a -7.3 a -6.3 a Fully watered baseline -4.1 -4.6 -4.9 -4.4 -3.9 Means followed by the same letter in a column are not significantly different comparing treatments within good or poor areas (P≤0.05). 2010

Midday stem water potential (bars) Treatment

6/01

/10

6/

14/1

0

6/

15/1

0

6/

21/1

0

7/0

7/10

7/

16/1

0

7/2

9/10

8/2

0/10

Good growth area Untreated control -3.1 a -3.9 a -3.3 a -3.8 a -3.4 a -3.4 a -3.7 a -3.9 a Kaolin sprayed -3.1 a -4.0 a -3.5 b -4.0 a -3.9 b -3.7 a -3.9 a -3.9 a Fully watered baseline -3.6 -4.8 -3.9 -4.8 -4.3 -4.3 -4.3 -4.4 Poor growth area Untreated control -4.8 a -5.9 a -5.7 a -5.8 a -4.8 a -5.0 a -5.8 a -6.4 a Kaolin sprayed -5.1 a -6.1 a -6.0 a -6.4 a -5.2 a -5.6 a -6.0 a -6.4 a Fully watered baseline -3.8 -4.8 -4.5 -4.8 -4.3 -4.3 -4.3 -4.4 Means followed by the same letter in a column are not significantly different comparing treatments within good or poor areas (P≤0.05). Table 2. Solano County site. Midday canopy light interception for 2009 season as measured with the Kawasaki Mule mounted mobile light bar. Data is for entire row including good and poor growth parts of orchard. Measurements done on June 2 were before first Surround® application, June 17th was after first Surround® application and July 13th was after second Surround® application. Data is for entire row, including both good and bad growth areas. Letters indicate significant difference at 5% level of significance. Midday canopy light interception (%) Treatment 6/02/2009 6/17/2009 7/13/2009 8/30/10 Untreated control 68.4 a 70.3 a 71.1 a 79.1 a Kaolin treated 70.1 a 71.6 a 72.9 a 80.2 a Means followed by the same letter in a column are not significantly different (P≤0.05).


Table 3. Solano County site. Nut quality summary. Letters indicate significant difference at 5% level of significance. 2009 Treatment

Nut weight

(g)

Large (%)

Medium

(%)

Baby (%)

Stained

(%)

Adhering hull (%)

Insect damaged

(%)

Mold (%)

Reflected light index

Untreated control

12.93 a

76.4 a

0.6 a

0.6 a

1.2 a

0.8 a

0.3 a

0.7 a

51.2 a

Kaolin treated 12.80 a 76.8 a 1.1 a 0.7 a 2.9 a 1.1 a 1.1 a 2.0 a 51.1 a 2010 Treatment

Nut weight

(g)

Large (%)

Medium

(%)

Baby (%)

Stained

(%)

Adhering hull (%)

Insect damaged

(%)

Mold (%)

Reflected light index

Untreated control

12.99 a

99.4 a

1.0 a

0

1.8 a

0 a

0.2 a

0.1 a

52.4 a

Kaolin treated 12.60 b 98.9 a 1.1 a 0 2.5 a 0 a 0.4 a 2.0 a 51.9 a Table 4. Solano County site. 2010 seasonal average midday stem water potential, midday canopy photosynthetically active radiation interception, yield and yield per unit PAR intercepted by treatment for good growth versus bad growth areas of orchard. Yield per unit PAR intercepted was calculated with Aug. 30, 2010 PAR data. Letters indicate significant difference with either good or poor growth area at 5% level of significance. Treatment

Seasonal average

midday stem water potential

(bars)

Aug. 30, 2010 Midday canopy

light interception (%)

Oct. 20, 2010 Midday canopy

light interception (%)

Yield (tons/acre)

Yield per unit light

intercepted Good growth area

Untreated control -3.6 a 91.2 a 89.4 a 2.59 a 0.023 a Kaolin treated -3.7 a 89.1 b 77.2 b 2.22 b 0.019 b

Poor growth area Untreated control -5.7 a 54.9 a 32.8 a 1.68 a 0.029 a Kaolin treated -5.6 a 62.3 a 41.9 a 1.80 a 0.025 a


Table 5. Yuba County site #1 (Howard). 2009 walnut yield, midday canopy light interception and yield per unit midday canopy light intercepted (measured on 7/14/10) for aerial versus ground Surround® compared to untreated control (5% level of significance).

Treatment Yield

(tons/ac)

Midday canopy light interception

(%)

Yield per unit midday canopy

light intercepted

Control 3.60 a 70.1 a 0.052 a Surround® aerial 3.59 a 70.2 a 0.051 a Surround® ground 3.60 a 70.1 a 0.051 a

Table 6. Yuba County site #1 (Howard). 2009 walnut quality for aerial versus ground Surround® compared to untreated control (5% level of significance).

Treatment

%large sound

%Edible Yield

% Extra Light

%Light

%Total Light

Control 82 a 52 a 30 a 47 a 77 a Surround® aerial 80 a 51 a 32 a 49 a 81 a Surround® ground 82 a 51 a 19 b 52 a 71 a

Table 7. Yuba County site #2 (Tulare). 2009 walnut yield, midday canopy light interception and yield per unit light intercepted intercepted for aerial Surround® compared to untreated control (5% level of significance).

Treatment Yield (tons/ac)

Midday canopy light interception

(%)

Yield per unit midday canopy

light intercepted

Control 2.50 a 78.1 a 0.032 a Aerial Surround 2.75 a 73.8 a 0.038 a

Table 8. Yuba County site #2 (Tulare). Surround® trial Yuba County. 2009 walnut quality for aerial Surround® compared to untreated control (5% level of significance).

Treatment

%large sound

%Edible Yield

% Extra Light

%Light

%Total Light

Control 89 a 49 a 0 a 62 a 62 a Aerial Surround® 92 a 50 a 0 a 65 a 65 a


Fig. 1. Solano County site 2009. Stem water potential versus maximum, average and minimum leaf temperature as measured with Flir thermal imaging camera on July 13, 2009 in the morning and afternoon.

Fig. 2. Solano County site 2009. Midday canopy light interception measured with the Kawasaki mounted lightbar on June 2, June 17 and July 13, 2009. Top two graphs are good growth of orchard and bottom two graphs are the poor growth part of the orchard (seen in the north west section of the orchard in the aerial image).

July 13, 2009 AM

Stem water potential (bars)

-7.5 -7.0 -6.5 -6.0 -5.5 -5.0 -4.5 -4.0 -3.5

Max

imum

tem

pera

ture

(deg

C)

20

25

30

35

40

45

50

Control maximumr2 = 0.04Surround maximumr 2 = 2.46Control averager2 = 0.41Surround averager 2 = 0.01Control minimumn/a (all values 26degC)Surround minimumn/a (all values 26degC)

max

avemin

July 13, 2009 PM

-7.5 -7.0 -6.5 -6.0 -5.5 -5.0 -4.5 -4.0 -3.5

Control maximumr2 = 0.02Surround maximumr 2 = 0.10Control averager2 = 0.01Surround averager 2 = 1.08Control minimumn/a (all values 26degC)Surround minimumn/a (all values 26degC)

max

ave

min

Surround treated

2009-6-1

2009-6-8

2009-6-15

2009-6-22

2009-6-29

2009-7-6

2009-7-13

Surround treated

2009-6-1

2009-6-8

2009-6-15

2009-6-22

2009-6-29

2009-7-6

2009-7-13

Untreated control

2009-6-1

2009-6-8

2009-6-15

2009-6-22

2009-6-29

2009-7-6

2009-7-130

20

40

60

80

100

Rep 1Rep 2Rep 3Rep 4Rep 5Rep 6

High canopy cover part of orchard

Untreated control

2009-6-1

2009-6-8

2009-6-15

2009-6-22

2009-6-29

2009-7-6

2009-7-13

Mid

day

PA

R in

terc

eptio

n (%

)

0

20

40

60

80

100

Rep 1Rep 2Rep 3

Low canopy cover part of orchard


Fig. 3. Solano County site 2009. Average temperature and relative humidity inside interior of tree canopy in 2009. Each line represents data from six dataloggers, one in each block for each treatment. Times when temperatures were significantly different are noted (5% level of significance).

Aug. 4, 2009

Can

opy

tem

pera

ture

(deg

C)

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15

20

25

30

35

ControlSurround

23:00:00

01:00:00

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23:00:00

Rel

ativ

e hu

mid

ity (%

)

30

40

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ControlSurround

no significant differences

Aug. 12, 2009

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opy

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(deg

C)

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ControlSurround

23:00:00

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significantly different from19:15 to 20:00

June 18, 2009

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(deg

C)

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ControlSurround

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Sept. 2, 2009

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C)

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23:00:00

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07:00:00

09:00:00

11:00:00

13:00:00

15:00:00

17:00:00

19:00:00

21:00:00

23:00:00

Rel

ativ

e hu

mid

ity (%

)

30

40

50

60

70

80

90

100

ControlSurround

significantly different from17:10 to 17:35 and from 18:15 to 18:25

June 17, 2009

Can

opy

tem

pera

ture

(deg

C)

10

15

20

25

30

35

Untreated controlSurround

12:00:00

13:00:00

14:00:00

15:00:00

16:00:00

17:00:00

18:00:00

19:00:00

20:00:00

21:00:00

22:00:00

23:00:00

00:00:00

Rel

ativ

e hu

mid

ity (%

)

30

40

50

60

70

80

90

100


Aug. 18, 2009

Can

opy

tem

pera

ture

(deg

C)

10

15

20

25

30

35

ControlSurround

23:00:00

01:00:00

03:00:00

05:00:00

07:00:00

09:00:00

11:00:00

13:00:00

15:00:00

17:00:00

19:00:00

21:00:00

23:00:00

Rel

ativ

e hu

mid

ity (%

)

40

50

60

70

80

90

100

ControlSurround

no significant differences


Fig. 4. Solano County site 2010. Temperature (upper left), relative humidity (lower left) in canopy for datalogger in good growth area. Temperature (upper right) and relative humidity (lower right) for poor growth area is also shown. Data is for June 21, 2010. Dip in temperature and peak in relative humidity around 8am is likely due to clouds. Fig. 5. Yuba County site #2 (Tulare). Tree count versus Midday canopy light interception measured with the mobile platform lightbar. The tree count was a simple count of the number of trees that were missing in each row (including partial trees that had lost some percentage of their canopy).

Ju e , 0 0Te

mpe

ratu

re (d

eg F

)

50

55

60

65

70

75

80

85

90

Contol good growthSurround good growth

Control poor growthSurround poor growth

23:00:00

03:00:00

07:00:00

11:00:00

15:00:00

19:00:00

23:00:00

Rel

ativ

e H

umid

ity (%

)

20

40

60

80

100

Control good growthSurround good growth

23:00:00

03:00:00

07:00:00

11:00:00

15:00:00

19:00:00

23:00:00

Control poor growthSurround poor growth

Good growth area Poor growth area

Tree count

42 44 46 48 50 52

Per

cent

PA

R in

terc

eptio

n

60

65

70

75

80

85

90

ControlPlot 1 RegrSurroundPlot 2 Regr

r2 = 0.72

r2 = 0.76


KAOLIN PARTICLE CLAY FILM EFFECTS ON ...walnutresearch.ucdavis.edu/2010/2010_269.pdfKaolin particle...

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