Light use efficiency (LUE) determines biomass production based on interception energy during photosynthesis. The product of photosynthesis is allocated to the plants organs based on the partitioning of carbohydrates. The LUE and carbohydrate partitioning are two important parameters in crop modelling. The research was conducted at Cikabayan experimental station of IPB, Bogor from July to November 2015. The experiment was designed according to a randomize block design with five replications. The fertilizer treatments rate were 0%, 50%, 100%, 150%, and 200% of reference N fertilization of 120 kg ha-1.  The  value  of  light use efficiency and the partition coefficient of sorghum were not affected by N fertilization. The value of light use efficiency is 1.41 g MJ-1. The carbohydrates partitioning was developed based on plant growth stage. The partition from the planting to the emergence stage (0 ≤ s ≤ 0.25) was 0.81 x s/0.25 root, 0 stem, 0.19 x s/0.25 leaves, and 0 panicle. The partition from the emergence to the maximum vegetative stage (0.25 &lt; s ≤ 0.5) was 0.81-(0.59 x s/0.5) root, 0.14 x s/0.5  stem, 0.19 + (0.45 x s/0.5) leaves, and 0 panicle. The partition from the maximum vegetative stage to the flowering stage (0.5 &lt; s ≤ 0.75) was 0.22 - (0.09 x s/0.75) root, 0.14 + (0.39 x s/0.75) stem, 0.64 - (0.46 x s/0.75) leaves, and 0.16 x s/0.75 panicle. The partition from flowering to the harvest stage (0.75 &lt; s ≤ 1) was 0.13 - (0.13 x s) root, 0.53 - (0.52 x s) stem, 0.18-(0.18 x s) leaves, and 0.16 + (0.84 x s) panicle.<br /><br />Keywords: crop modelling, light use efficiency, N fertilizer, partitioning carbohydrates<br /><br />

Nutrients are needed to increase crop production. Liquid fertilizer (bio-urine), which macro elements, easily absorbed by plants and quickly shows results with optimum concentration, is one of the organic fertilizers that can be used as a trigger for the growth of potted chrysanthemums. The aim of this study to determine the optimum concentration of bio-urine in potted chrysanthemum cultivation. This research was conducted from October to December 2020 at West Sumatera AIAT’s greenhouse on altitude of 1000 m above sea level, was designed with a Randomized Complete Block Design and five replications. Observed consist of five concentrations of bio-urine, namely (1) 200 ml L-1 of water, (2) 100 ml L-1 of water, (3) 66.67 ml L-1 of water, (4) 50 ml L-1 and (5) 40 ml L-1 of water. Parameters observed were plant height, number and length of internodes, number of branches, stem diameter, flower initiation, number and diameter of flowers, and petiole length. The result shows that Bio-urine with a concentration of 100 ml L-1 of water produces potted chrysanthemum with optimum parameters of plant height, number of internodes, number of branches, stem diameter, number of flowers, flower diameter, and petiole length.