Irrigation scheduling of fruit trees

Transcription

1 Irrigation scheduling of fruit trees Amos Naor Water stress assessment The interaction of crop-load with irrigation

2 Soil water stress indicators

3 Soil water potential - Tensiometer

4 Soil water potential - Tensiometer The tensiometer is a pipe filled with water that has ceramic (porous) cup in the bottom. Ceramic cup The tensiometer exchanges water with the soil-water until their water potentials are equal.

5 Soil water content All the modern measurement techniques of water content are based on electrical properties Capacitance. Dialectric constant. Resistance.

6 Plant water stress indicators

7 Plant-based water stress indicators Water potential (pressure chamber, psychrometry). Relative water content. Tissue size changes (dendrometers). Stomatal conductance Porometry IR thermometry / Thermal imaging Acoustic emission Sap flow

8 Plant-based water stress indicators Water potential (pressure chamber, psychrometry). Relative water content. Tissue size changes (dendrometers). Stomatal conductance Porometry IR thermometry / Thermal imaging Acoustic emission Sap flow

9 Direct measurement of the water potential Pressure Pressurized nitrogen chamber (Scolander et al., 1965)

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11 Stem water potential Leaf water potential

12 Trunk diameter changes Trunk diameter changes :00 6:00 12:00 18:00 hour

13 Various commercial water stress probes

14 Thermal imaging The energy from the sun is directed mainly to: Heating the canopy. Vaporizing water (transpiration) Stressed plants close their stomata and reduce transpiration thus more energy from the sun is shifted to heat the canopy. Stress plants are warmer than non-stressed plants

15 Thermal imaging: (Moeller et al., 2007)

16 High irrigation rate Low irrigation rate High irrigation rate

17 Relationships between CWSI and stomatal conductance (Moeller et al., 2007) CWSI = (T Canopy T wet ) / (T dry T wet ) 500 Stomatal conductunce (mmole/m 2 /s) r 2 = CWSI

18 Relationships between CWSI and stomatal conductance (Moeller et al., 2007) CWSI = (T Canopy T wet ) / (T dry T wet ) 500 Stomatal conductunce (mmole/m 2 /s) r 2 =0.85 Optimal meteorological conditions. Good reference temperatures. High spatial resolution CWSI

19 Pixel size and average temperature Reducing spatial resolution Current accuracy of CWSI assessment is limited Crane Satellite Airplane

20 Summary of water stress indicators for irrigation scheduling Point Vs. spatial measurements Setting thresholds (calibration)

21 Detection of irrigation malfunctions: grapevines not irrigated currently not irrigated currently currently irrigated Thermal imagery allowed the recognition of subsurface water flow from the nectarines Vineyard, Upper Galilee, summer 2005 Alchanatis and Cohen

22 Leakage detection

23 Almonds Alchanatis et al 23

24 Clogging in drippers Cohen and Alchanatis Cotton, Northern Israel, Megido, July, 2008

25 Irrigation malfunction detection in olives (Alchanatis et al) Date suspected points (area) Visible leaks No visible leaks Olives Gshur 24/6 5.4% 8% 92% 26/8 8.2% 11% 89%

26 Crop load and irrigation

27 Transpiration (l/plant) Leaf area (m 2 ) Crop load and water consumption (Lenz, 1986) Apple trees were grown in containers. Trees with and without fruits were compared. Transpiration and leaf area were measured. Stomatal aperture is higher in the presence of fruit Leaf area per tree No fruit Fruit Transpiration No fruit Fruit

28 Crop load and stem water potential Nectarine c b b b b b ab a a a a a Pan evaporation coeff. Frut/tree

29 Number of fruits and stem water potential Fruit per tree

30 Crop load and stem water potential Average midday stem water potential up to harves (MPa) L 1M 1H 3L 3M 3H 7L 7M 7H Apple Ortal Matityahu

31 Stem water potential (MPa) Stomatal conductance (mmole/m 2 /s) Crop load and stem water potential Crop load and Stomatal conductance Low load Olive High load Olive Low load High load Low irr Med irr High irr 0 Low irr Med irr High irr

32 Stomatal conductance (mmole/m2/s) Stomatal cinductance (mmole/m2/s) Crop load and water relations in olive Med. load 14:00 Low load 10:00 High load 10:00 R 2 = 0.96 R 2 = 0.92 R 2 = Stem water potential (MPa)

33 Assimilation rate (μmole/m2/s) Crop load and water relations in apple Naschitz et al, unpublished High crop load Low crop load Midday stem water potential (MPa)

34 (g) משקל פרי weight ממוצע Fruit )גרם( Stem water potential and apple fruit weight 250 Ortal אורטל Matityahu מתיתיהו Low and Med. crop load R 2 = R 2 = 0.94 High crop load פוטנציאל (MPa) מיםSWP בגזעMidday )MPa(

35 אחוז (%) פרי mm גדול > 70 מ- 70 Fruit מ"מ Stem water potential and the yield of large fruit 100 Matityahu מתיתיהו Ortal אורטל Low and Med. crop load 80 R 2 = High crop load פוטנציאל (MPa) מים SWP בגזעMidday )MPa(

36 Fruit weight (g) Crop load and thresholds for irrigation (Naschitz et al, unpub.) Fruit/tree 300 fruit/tree 600 fruit/tree >1000 fruit/tree 25 t/ha 58 t/ha 93 t/ha Irrigation levels: 1 mm/day 3 mm/day 7 mm/day Optimal irrigation: 25 t/ha - ~2.5 mm/day 58 t/ha - ~4.5 mm/day 93 t/ha - ~7 mm/day 50 0 Optimal threshold: 25 t/ha - ~-1.4MPa 58 t/ha - ~-1.2MPa t/ha - ~-0.8MPa Midday stem water potential (Mpa)

37 Transpiration (l/plant) Summary of crop load and irrigation No fruit Fruit

38 Summary of water stress indicators for irrigation scheduling Point Vs. spatial measurements Setting thresholds (calibration)

39 Summary of irrigation malfunction detection

40 Thanks