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A Three-State Pecan-Almond Project: Help from Physiological Models, Remote Sensing, & Ground-Based PowerPoint Presentation
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A Three-State Pecan-Almond Project: Help from Physiological Models, Remote Sensing, & Ground-Based Measurements. Vince Gutschick, Global Change Consulting Consortium, Inc. Ted Sammis, Plant & Environmental Science, NMSU Junming Wang, Plant & Environmental Science, NMSU

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slide1

A Three-State Pecan-Almond Project:

Help from Physiological Models,

Remote Sensing, & Ground-Based

Measurements

Vince Gutschick, Global Change Consulting Consortium, Inc.

Ted Sammis, Plant & Environmental Science, NMSU

Junming Wang, Plant & Environmental Science, NMSU

Manoj Shukla, Plant & Environmental Science, NMSU

Rolston St. Hilaire, Plant & Environmental Science, NMSU

slide2

Challenges

  • Water shortages  deficit irrigation - what schedule is best?
  • General resource management, including N
  • Crafting plans and management tools
  • Optimal deficit irrigation – guidance from models <-> experiments
  • Develop monitoring, particularly ET - large areas, near-real time
  • Validate monitoring methods
  • Develop simple management plan – distill the knowledge
  • Validate the management plan
  • Deliver practical tools
  • NMSU part:
  • Focus on pecans
  • Development of framework applicable to other nut crops
slide3

First three elements

  • Optimal deficit irrigation
  • Maximal retention of yield and yield capacity
  • Zillion risky expts.? No. Use models:
    • To develop hypotheses
    • Then to guide experimental design and interpretation
  • Monitoring – cover large areas, in near-real time
    • Satellite estimates of ET by energy balance
  • Validate monitoring
    • Eddy covariance, SWB, and physiological stress measures (optical…)
slide4

Three more elements

  • Develop a simple management plan
    • Distill the response of yield to fraction of normal
    • water use (ET) – that is, yield as Y(E/E0)
  • Validate optimal management results
  • Deliver practical tools
    • Monitoring of stress indicators, not just end yield
    • Using simple, mostly automated tools
      • Simpler is better - experience of DSSs, and
      • even simpler tools (nomograms,…)
      • Novel satellite estimates of ET in near-real time
      • Easily obtained ground data
slide5

Highlight: satellite estimates of ET by energy balance

- a large-scale, rapid tool for monitoring stress

and water use

  • Modification of Surface Energy Balance Land (SEBAL)  RSET
  • Key problem avoided: low accuracy of surface temperature
    • Including atmospheric effects, view angle (air mass) effects
  • Remaining difficulty – disparity of aerodynamic resistance for
    • soil & canopy(2 sources)
    • Some clues for future
    • Even “as is” -for ag areas with good cover, not a big problem
  • Automation a challenge
    • Finding and processing scenes
    • Locating hot and cold spots
      • Including correction for differences in elevation, θ (VPT)
slide8

Highlight: modelling plant responses to stress,

for yield optimization

Where do we want to end up?

Whole-season water use and yield

 Leafout (canopy leaf area, as a function of E/E0)

 Nutfill (canopy photosynthesis, as a function of E/E0

 Concurrent information: PS partitioning, leaf N dynamics

  • What we do know?
  • What have physiological models given us over the years?
  • Decision support systems Erect leaf varieties ……
  • Great detail needed in models  great body of knowledge
    • E.g., Ball-Berry, Farquhar et al., micromet, light interception… interception, LA phenology, Vcmax(stress), gs(stress - Tardieu…)
    • Specific to pecans
      • Our previous models
      • Gas-exchange and stress data of David Johnson
slide9

What we don't know well enough & therefore need to measure

    • Seasonal patterns of stomatal control and WUE
  • What’s the unstressed Ball-Berry slope?
  • Does it really double from pre-monsoon to monsoon?
  • Evidence: gain in water-use rates
  • (Basis in ecology under natural conditions?)
slide10

How does the Ball-Berry slope respond to root or leaf water potential?

How much do we need to cut it to reduce E to 0.5 E0?

How does WUE change under stress?

2. Seasonal patterns of photosynthetic capacity (Vc,max25)

and relation to leaf N content (linear? intercept = ??)

slide11

Optimality

  • Distill the more detailed physiological and developmental
  • models of:
    • Leaf area development – to a simple function of fraction of
  • unstressed ET (E/E0)
  • Basically, reset leaf area to a smaller fraction of normal,
  • reducing future ET demand
    • Canopy photosynthesis – to a similarly simple function of E/E0)
  • See a gain in water-use efficiency that makes the cut in
  • season-total photosynthesis less than the cut in water use
  • Find the combination of cuts in E/E0 in both stages that
  • leaves the greatest nut yield, for a given total water use
  • (a numerical solution)
slide12

Data needs for studies of stress responses and optimization

  • - under several stress levels (treatments and interplant/
  • microsite variation)
    • Leaf gas exchange
      • To eludicate the stomatal control program
        • Aerial environment (2 fundamental parameters)
        • Water stress (3rd fundamental parameter)
      • To estimate photosynthetic capacity (Vc,max25) and its
    • relation to leaf N and light integral on the leaf
    •  Concurrent measurements of leaf N and PAR levels
    •  Determining seasonal trends in both
    • Water stress quantification – soil water balance and
  • soil moisture release curve
    • Measurements of growth, carbohydrate reserves, and nut yield