On the relation between the sown density and the germinating rate of grass seeds

Abstract

Germination tests of gtasses under several conditions of the sown densty and the water supply were carried out to make sure of the relation between the sown density and the germinating rate.
The results were obtained as follows.
The germinating rate in high density plots with insufficient water went down significantly and moreover, the germination was delayed for 3 days, in comparison with sufficient water plots.(Table 1, 2 and Fig. 1). This was certified also by the water content per oneseed.(Table 3, 4 and Fig. 3).
Those phenomena were considered as the results of the scramble for water.
Here, the authors introduce the following formulae on the relation between the sown density and the germinating rate.
_??_ (1)
where,
r: germinating rate
ρ: sown density
h: quantity of water
This formula explains that the augmentaion of the germinating rate is inversely proportionate to the increase of the sown density at a certain water supply.
The following formulae are obtained by working out this differential epuation (1).
log r=-a·logδ+log R (2)
or,
r=R·ρ^-a (3)
moreover, with avalable space per one seed (δ) instead of density (ρ), Formula (3) is shown as follows;
r=R·δ^a (4)
where, the constant (a) is determined by water condition, and the constant of integration (R) is the maximum germinating rate under sufficient water condition.
The r-ρ or r-δ curves are shown in Fig 4 and 5 in logarithmic diagrams. The character of these curves is explained in Fig 6, 7 and 8.
In conclusion, these results are noteworthy for the determination of the sown density of grasses.