Effect of Electrical Conductivity of the Soil Solution on Stem Elongation in Fertigated Roses

Transcription

1 Effect of Electrical Conductivity of the Soil Solution on Stem Elongation in Fertigated Roses Heiner Lieth and Lorence R. Oki Department of Environmental Horticulture University of California

2 Introduction: Prof Heiner Lieth Research: Mathematical modeling of greenhouse crops (roses, orchids, lily) Greenhouse environment control automation (irrigation, temperature, light, CO, etc) Extension: Greenhouse and nursery crop production Teaching Greenhouse production management Mathematical modeling in horticulture

3 Introduction: Prof Heiner Lieth Rose Research: Development of a crop simulation model for cut-flower roses Optimal irrigation in roses, especially in hydroponics Also note: in roses, stem length is of ultimate importance Roses are graded by length The longer the rose stem, the higher the price. Thus: quantitative analysis of rose stem length is important (it can help us optimize)

4 Introduction: Prof Heiner Lieth Outline of today s presentation: Background of irrigation work Research on rose stem elongation Methodology Experimental design Results of effect of salinity on stem length Summary/Conclusions

5 Background Previous research: Irrigation based on soil moisture tension increased stem length Led to development of tensiometer-based irrigation techniques Left us with the question: why? Evidence suggested salinity might be an issue Objective of research project presented today: Track stem elongation rates while irrigating with solutions of different salinity levels Investigate whether horticultural (irrigation) methods can be modified to optimize final stem length

6 Methods Plant material: Kardinal roses Measuring stem elongation

7 Methods Plant material: Kardinal roses Measuring stem elongation Linear Displacement Position Sensor (LDPS) Screen cone Connecting rod Salinity measurement Measured as EC (electrical conductivity) Measure continually LDPS body Core

8 EC Probe Setup Electrical lead Tubing fitting EC cell body Thermistor Electrode bands

9 EC Probe Setup Electrical lead Tubing fitting EC cell body Plastic tube Thermistor Electrode bands Flow Channels Volume reducer Ceramic cup

10 EC Probe Setup Campbell CR3X EC probe Output channels 13 EC Meter Input channels Tubing Computer Flask

11 EC Probe Setup Campbell CR3X Multiplexer Output channels 13 EC Meter Input channels Computer

12 Methods Plant material: Kardinal roses Measuring stem elongation Linear Displacement Position Sensor (LDPS) Salinity measurement Measured as EC (electrical conductivity) Measure continually Needed to find a way to compare stem elongation of different stems (to study effects of treatments, when should elongation be measured?)

13 6 Stem Elongation Length rate and changes Leaf Unfolding during stem development Sep 5 - Oct 3 Stem Length (cm) bars= ±1SE n=1 VB HV Number of Leaves Unfolded 1 3 Number of Days Since Budbreak

14 6 Stem Length and Leaf Unfolding Sep 5 - Oct 3 Stem Length (cm) bars= ±1SE n=1 VB HV Number of Leaves Unfolded 1 3 Number of Days Since Budbreak

15 6 Stem Length and Leaf Unfolding Sep 5 - Oct 3 Stem Length (cm) bars= ±1SE n=1 VB HV Number of Leaves Unfolded 1 3 Number of Days Since Budbreak

16 Patterns in rose stem elongation rate Elongation rate changes during stem development Constant elongation rate from unfolding of fifth to ninth leaf Elongation rate changes diurnally: Growth chamber: Relative elongation rate Lights on Lights off bars= ±1SE symbols represent 36 observations 6: 9: 1: 15: 18: 1: : 3: 6: Time of day

17 6: 9: 1: 15: 18: 1: : 3: 6: Time of Day Patterns in rose stem elongation rate Elongation rate changes during stem development Constant elongation rate from unfolding of fifth to ninth leaf Elongation rate changes diurnally: Greenhouse Relative Elongation Rate sunrise Error Bars=+/- 1SE Data collected Aug 1-15, 1998 symbols represent 36 observations sunset Note: best time to do measurements is at night!

18 Treatments Two Experiments Short term exposure to salinity Longer duration exposure In each case, track elongation for 1 hours Treatment procedure Apply regular nutrient solution at 1: a.m. Track and log baseline elongation rate Apply treatment solution at 3: a.m. DI, NS, +1, +, +, and +8 ds/m Track and log treatment elongation rate Apply regular nutrient solution to flush at 5: in short-term experiment, else at 15: Track and log post-treatment elongation rate

19 Automated treatment application Campbell CR3X Output channels Input channels Nutrient Solution Line Valve Pump Treatment Solution

20 Equipment setup LDPS EC probe Tensiometer

21 8 7 Substrate Electrical Conductivity EC (ds/m) 5 3 valve on treatment + + valve on Duration (sec) +1 1 NS DI : 3: 6: 9: Time of Day

22 Effect of salinity on stem elongation rate Actual rates. Stem Elongation Rate (mm/hr) PreTrmt Bars= ±1SE +/-1 SE. n= DI NS +1 ds/m + ds/m + ds/m +8 ds/m Treatments

23 Effect of salinity on stem elongation rate Actual rates. PreTrmt Trmt 1.5 Bars= ±1SE +/-1 SE n= DI NS +1 ds/m + ds/m + ds/m +8 ds/m Reduction in stem elongation rate with increasing EC Treatments Stem Elongation Rate (mm/hr)

24 Effect of salinity on stem elongation rate Actual rates Stem Elongation Rate (mm/hr) PreTrmt Trmt PostTrmt Bars= ±1SE +/-1 SE. n= DI NS +1 ds/m + ds/m + ds/m +8 ds/m Treatments

25 Effect of Salinity On Growth Rate Treatment applied NS applied Stem Elongation Rate (mm/hr) n=8 + ds/m Bars= ±1SE 1: 3: 5: 7: Time of Day

26 Stem Elongation Rate (mm/hr) Effect of Salinity On Growth Rate DI NS +1 ds/m Treatment Leaching Treatment Leaching Treatment Leaching + ds/m + ds/m n=13 n=11 n=9 Bars= ±1SE +8 ds/m n=1 n=8 n=1 1: 3: 5: 7: 1: 3: 5: 7: Time of Day 1: 3: 5: 7:

27 9 8 Treatment Substrate Electrical Conductivity +8 n=9 Electrical conductivity (ds m -1 ) Error bars= +/-1SE NS DI Treatment solution EC 1: 3: 5: 7: 9: 11: 13: 15: Time of Day n=1 n=8 n=7 n=7 n=5

28 Effect of Salinity on Rose Stem Elongation Actual Growth Rates DI Treatment Treatment Treatment NS +1 Growth Rate (mm/hr) n=6 + n=7 + n=7 +8 Error bars= +/-1SE n=8 n=1 n=9 1: 5: 9: 13: 1: 5: 9: 13: Time of Day 1: 5: 9: 13:

29 Summary Salinity can reduce the stem elongation rate The higher the salinity, the greater the inhibition Stem elongation rates recover from a short exposure to a high EC solution but not to pretreatment levels part of the loss is permanent

30 Questions? For more info: Professor Heiner Lieth Mail: Environmental Horticulture, University of California, Davis, CA Tel: Fax: Web page: