Thermal time requirements for germination of four annual clover species

Figures & data

Figure 1 Cumulative germination of (a) ‘Cefalu’ arrowleaf, (b) ‘Bolta’ balansa, (c) ‘Prima’ gland and (d) ‘Mihi’ Persian clovers at 13 different constant temperatures. (•) 5 °C, (○) 8 °C, (▾) 10 °C, (▵) 12 °C, (▪) 15 °C, (□) 18 °C, (♦) 20 °C, (⋄) 22.5 °C, (▴) 25 °C, (▿) 30 °C, (⬢) 35 °C, (⬡) 37.5 °C, (×) 40 °C. Error bars represent the maximum standard error of the mean for final germination percentage.

Figure 2 Maximum germination (%) for ‘Cefalu’ arrowleaf (•), ‘Bolta’ balansa (○), ‘Prima’ gland (▾) and ‘Mihi’ Persian (▵) clovers at different constant temperatures.

Figure 3 Number of days to 75% of final germination for ‘Cefalu’ arrowleaf (•), ‘Bolta’ balansa (○), ‘Prima’ gland (▾) and ‘Mihi’ Persian (▵) clovers at different constant temperatures.

Figure 4 Germination rate of ‘Cefalu’ arrowleaf (•), ‘Bolta’ balansa (○), ‘Prima’ gland (▾) and ‘Mihi’ Persian (▵) clover at different constant temperatures.

Table 1 Base (T_b), optimum (T_opt) and maximum (T_max) temperatures and thermal time (Tt) requirements for 75% germination of ‘Cefalu’ arrowleaf, ‘Bolta’ balansa, ‘Prima’ gland and ‘Mihi’ Persian clovers.

Cultivar	Tb (°C)	Topt (°C)	Tmax (°C)	Ttsub (°Cd)	Ttsup (°Cd)	^aTt (Tb=0°C) (°Cd)	^bExcluded temperatures
‘Cefalu’	1.4	19.7	34.8	30	25	34	37.5, 40
‘Bolta’	2.6	19.7	33.9	26	21	32	37.5, 40
‘Prima’	0.1	16.2	34.1	29	32	28	37.5, 40
‘Mihi’	4.5	32.6	45.4	19	9	25	_
Max s.e.	0.48	1.22	0.88	1.8	4.9	1.3
95% c.i.	−5.0, 10.5	13.8, 34.7	25.7, 53.6

^a Analysis assumes a base temperature of 0 °C.

^b Excluded temperatures because germination rate deviated from the linear model.

Tt_sub, from T_b to T_opt

Tt_sup, from T_opt to T_max

s.e. Standard error.

c.i. Confidence interval.