アルファルファ草地の生産生態に関する研究 : 第2報 群落内の枯死個体について

抄録

Dead plants in alfalfa swards were examined from data of agrontomic characters such as plant height, dry weight per plant and stem numbers per plant at each harvest for three years, by selecting l00 plants at random and respectively from two alfalfa swards (625 plants/m² and 169 plants/m²) of different densities as stated in the previous report. Results obtained are as follows: 1. Most of the dead plants in the swards showed values less than the mean value of totalplants in plant height, stem unmbers and dry weight per plant at the previous harvest. Especially, in dry weight per plant, many dead plants indicated the values which were close to the minimum value. 2. Among the dead plants, about 70 per cent in 625 plants/m²-sward and 80 per cent in 169 plants/m²-sward had smaller values than x^^--s value (mean value rninus standard deviation after logarithm transformation of measured value) at least at the last harvest prior to recognition of death. The dead plants were classified into the following four types according to their growing process until the last harvest prior to death. Type I : Dead plants having greater values than x^^--s one at each harvest until a certain harvest time and also only one smaller value than x^^--s one at the last harvest prior to death. Type II : Dead plants having greater values than x^^--s one at each harvest until a certain harvest time andt smaller values than x^^--s one at several harvest times prior to death. Type III : Dead plants having smaller values than x^^--s one at eacLh harvest prior to death from the first harvest in the seeding year. Type IV : Dead plants having greater values than x^^--s one at each harvest prior to death.