DavidJohnston491
commented
2 years ago @apsiamsuer , the cotton model's radiation interception is described in Hearn (1994) OZCOT paper (page 265). The APSIM cotton component still uses these original equations. The radiation intercepted is governed by the plant's LAI. The only varietal parameter that directly affects this is the 'flai' parameter which is the scaling factor for leaf area per fruiting site. Values are limited to the 0 to 1 range. Okra leaf default is 0.52 and normal leaf varieties default is 0.87 . Other factors that will affect LAI (and therefore radiation interception) are the max leaf area increase per node per day (dlds_max default of 0.12) and rate of node development. This all gets tied up with CarryCapacity (see OZCOT paper), and all is affected by the model's internal representation of the soil moisture, the 'SMI' value. There are no varietal parameters for specifying transpiration efficiency coefficients. For early growth you can try adjusting 'DDISQ' (the day degree sum to first square). This is a critical point in the model where it changes growth equations from being driven by leaf growth, to a model being driven by fruiting dynamics with LAI then being linked to the fruiting sites. The cotton model does not follow the pattern of many of the other APSIM crop models, so there will be parameters that probably should be available, but are not. Hope this helps. DJ.
Do the radiation interception and transpiration efficiency coefficients of the cotton variety parameters have an important effect on the growth period and yield of cotton, and what are their names, default values, and range of values in the model? I would very much appreciate your answer!