Day 1 09:00A 0 µmol/m²/sSugar made 0 gBiomass 0 gStomata openFPS 0

CO₂ in O₂ / H₂O vapour out water up sugar down

3D view unavailable (WebGL not supported).
The physics, charts and the 2D leaf schematic keep running.

Plant Cutaway: Light, CO2 and Water to Sugar

One whole plant in cross-section: change light, CO₂, soil water and temperature, and watch the leaf trade water for carbon and grow.

Air and light

Soil and water

Time

Live readouts

Light response A(I)

Supply and demand A(Ci)

Soil water and stomatal opening over time

Missions

Independent numerical checks

Controls

Drag / one finger: orbit; wheel / pinch: zoom. Buttons Garden / Leaf / Roots fly the camera.
Keys: Left/Right = ±1 h of the day, Up/Down = light ±100, T / Shift+T = temperature ±1 °C, 1 2 3 = camera views, Space = pause, R = reset.
Day cycle on: the light slider is the peak (noon) PPFD and the sun follows sin(π(t−6)/12). Off: fixed light, so the curves respond immediately.
Time scale = simulated hours per real second. Particle rates are driven by the computed CO₂ uptake (A), transpiration (E) and sugar production; the plant grows with the carbon ledger.

The science

Overall reaction. 6 CO₂ + 6 H₂O + light → C₆H₁₂O₆ + 6 O₂. Atoms are balanced (the page counts them), and the model books 1 CO₂ : 1 CH₂O : 1 O₂.

Leaf photosynthesis (Farquhar–von Caemmerer–Berry, simplified C3). A = min(A_c, A_j) − R_d, A_c = V_cmax(C_i−Γ*)/(C_i+K_c(1+O/K_o)) (Rubisco-limited) and A_j = J(C_i−Γ*)/(4C_i+8Γ*) (light / RuBP-regeneration-limited). Electron transport follows the non-rectangular hyperbola θJ² − (αI+J_max)J + αI J_max = 0 with θ = 0.7, α = 0.3. Temperature uses Arrhenius factors (E_a: V_cmax 65, J_max 44 kJ/mol) and a high-temperature decline above about 38 °C. Parameters are textbook-type model values (Bernacchi-style at 25 °C), not a fit to any species.

Stomata. Ball–Berry: g_s = g₀ + g₁ A h_s/C_a, supply A = g_s/1.6 (C_a−C_i); the pair is solved by fixed-point iteration (20 steps). Transpiration E = g_s VPD / P. Drying soil closes stomata linearly between ψ_s = −0.5 and −2.5 MPa (Campbell retention curve for the soil). Open stomata let CO₂ in and water out: that trade-off is the central story.

Canopy, carbon and growth. Light per leaf area follows Beer–Lambert (k = 0.5) averaged over the canopy (big-leaf). Net CO₂ uptake is converted to CH₂O (30.03 g/mol); half is kept as dry mass (Y = 0.5, the rest stands for construction and maintenance respiration) and split leaf / stem / root 40 / 20 / 40 %, shifting to roots in drought and to leaves in shade. Leaf area = leaf mass × SLA.

Water. A single soil bucket (0.4 m deep under 0.05 m²) is filled by irrigation/rain, emptied by transpiration and drains above field capacity; the page checks the water ledger closes.

Honest simplifications. Big-leaf C3 only (no C4/CAM), no nitrogen limitation, no self-shading beyond Beer–Lambert, fixed leaf temperature = air temperature, one soil layer, quasi-steady leaf at 1-minute steps, particle counts are symbolic (not one per molecule). Typical-value model for teaching; not agronomic advice.

Educational model, not agronomic advice. The plant is a generic decorative herb. Models built with Blender (plant, roots, soil, terrain, molecules) and rendered with Three.js.