1. An evaluation method for evaluating a state of a photosynthetic sample with a photosynthetic function based on temporal data of a luminescence amount of delayed luminescence emitted from the photosynthetic sample, method performed on a hardware processor of a computer and comprising: a characteristic value computing step of computing on the hardware processor, for a plurality of time periods in the temporal data, characteristic values that indicate characteristics for predefined functions that represent timely evolution of luminescence resulting from different reactions in the photosynthetic sample; an evaluation value computing step of computing on the hardware processor an evaluation value by weighting the characteristic values; and an evaluation step of evaluating on the hardware processor the state of the photosynthetic sample based on the evaluation value by determining a degree of impact of the different reactions in the photosynthetic sample to decide whether the different reactions are harmful or not, wherein the characteristic value computing step comprises a fitting step of determining, as the characteristic values, coefficient values of the predefined functions so that the temporal data are fitted as a sum of the functions, in the evaluation value computing step, the evaluation value is computed based on the coefficient values determined in the fitting step, and the evaluation value is an area value computed based on coefficient values of at least one function among the plurality of functions, the predetermined functions are hill-shaped Lorentz functions, and when a i , b j , and c j (i=1, 2, 3) are the coefficient values of the plurality of functions and t is a variable indicating an elapsed time from a base time, the predetermined functions are respectively expressed as the following mathematical formulas: 10 c 1 1 + a 1 ⁡ ( t - b 1 ) 2 , ⁢ 10 c 2 1 + a 2 ⁡ ( t - b 2 ) 2 , ⁢ and ⁢ ⁢ 10 c 3 1 + a 3 ⁡ ( t - b 3 ) 2 ⁢ .