Garden with Insight v1.0 Help: Plant params development group
Life cycle type: Annual plants die at the end of one calendar year if they survived the winter or
dry season. Biennial plants die at the end of two calendar years if they survived. Perennial plants continue
to attempt to grow forever.
Plant is a legume: This plant is in the family Leguminosae,
which includes peas, beans, alfalfa, clover, and vetch. Legumes have a symbiotic relationship with
bacteria that live in root nodules and 'fix' atmospheric nitrogen as N2 (convert it to a usable organic form).
Plant is a tree: This plant is a tree. Tree growth has not been tested in this version of the
simulation.
Potential heat units at maturity: Number of heat units
required before plant is mature. Calculated from planting/harvest dates relative to frost (in cold climates)
or January 1 (in hot climates) and from days planting-maturity. Bounded by min and max heat units for
maturity.
Leaf area index (LAI) maximum: The maximum
leaf area index (LAI) for this plant. Leaf area index is the ratio of the
total area of all the plant's leaves to the ground area covered by the leaves. The more dense the plant's
leaves, the higher the leaf area index.
DMLA - Maximum potential leaf area index The parameters in the CLASCROP.DAT data set are
based on average plant densities in dryland (rainfed) agriculture. DMLA may need to be adjusted for
drought-prone regions where planting densities are much smaller or irrigated conditions where densities
are much greater.
S
Curve - effect of heat unit index on fraction of max leaf area index possible: Fraction of the maximum
leaf area index (Y) for a given heat unit index (X), before amendment by growth constraint and declining LAI from age.
DLAP1 - First point on optimal leaf area development curve *
DLAP2 - Second point on optimal leaf area development curve *
Two points on optimal (nonstress) leaf area development curve. Numbers before decimal are % of growing
season. Numbers after decimal are fractions of maximum potential LAI. Research results or observations
on the % of maximum leaf area at two points in the development of leaf area can be used in conjunction
with an EPIC simulation like that described for DLAI. The results of the one-year multi-run will establish
the cumulative heat units by month from planting to maturity. Then calculate percent of cumulative heat
units by dividing estimated cumulative heat units for each of the two months where you've estimated
percent of Max LAI by the average annual heat units shown on the bottom of the crop parameter set at the
beginning of the EPIC run. The percent of heat units for first monthly estimate is the number on the left of
the decimal for DLAP1 and the estimated percent of the Max LAI is the number in the right of the
decimal. DLAP2 is the same except the second month is used.
Heat unit index when LAI decline starts: The heat unit index at which leaves start to senesce (age) and the leaf area index (LAI) begins to decline, reducing photosynthetic efficiency and transpiration.
DLAI - Fraction of growing season when leaf area declines
The fraction of the growing season in heat units in divided by the total heat units accumulated between
planting and crop maturity. If the date at which leaf area normally declines is known, one of the drought
options in EPIC can be used to estimate the fraction of heat units accumulated. A multi-run EPIC
simulation is setup with IGSD equal to 366. A one-year simulation followed by a one-year multi-run will
produce a multi-run simulation which has average heat units per month and the total heat units to
maturity. The harvest date should be set to the crop maturity date. The estimated heat units at maximum
leaf area can then be divided by the heat units at maturity to estimate the fraction of the growing season at
which leaf-area-index start to decline.
Rate
of LAI decline: The rate at which the leaf area index (LAI) declines once the peak LAI has been
reached. Ranges between zero and ten. A decline rate of 1.0 makes a linear decline; a value greater than
one accelerates decline; and a value less than one slows decline.
RLAD - Leaf area index decline rate parameter
Leaf-area-index decline rate parameter (estimated LAI decline between DLAI (see parm 6) and harvest) -
1.0 is linear; > 1 accelerates decline; < 1 retards decline rate.
Adjustment to biomass-energy ratio if LAI declining: Reduces efficiency of photosynthesis due to leaf
senescence based on the simulated decline in leaf area index (LAI). Values below 1.0 reduce the effect of
LAI decline on photosynthetic efficiency; values above 1.0 increase the
effect.
Absolute frost kill temperature: If this is an annual, the
temperature at which this plant will die from frost. This parameter is not used for non-annuals. If the mean temperature for any day goes below this temperature, the entire plant
will die immediately.
Root fraction at emergence, by weight: The fraction of total
plant biomass (dry weight) expected to be allocated to the root at
emergence (just after germination). Used to calculate a daily proportion to allocate new photosynthate
between roots and shoots.
RWPC1 - Fraction of root weight at emergence
RWPC2 - Fraction of root weight at maturity
Partitioning parameters to split biomass between above ground and roots. RWPC1 is the partitioning
fraction at emergence and RWPC2 is partitioning fraction at maturity. Between those two points there is a
linear interpolation of the partitioning fraction relative to accumulative heat units.
Root fraction at maturity, by weight: The fraction of total plant biomass (dry
weight) expected to be allocated to the root at maturity (heat unit index
= 1.0). Used to calculate a daily proportion to allocate new photosynthate between roots and shoots.
Biomass allocation to storage organ at maturity, by weight:
The fraction by weight of the total plant biomass (dry weight) that the plant will attempt to allocate to its
storage organ at maturity.
Heat unit index at start of storage organ allocation: The heat unit
index at which allocation of new biomass (dry weight) to the storage organ should start. If there is no
storage organ this number should be zero.
If tree, years to maturity: If this plant is a tree, this is the number of years required before the
tree is considered mature. (The tree model in this version of the
simulation has not been tested.)
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