Table 1.

Heterogeneity evaluation of response ratios.

	Q	pq	I2	T2	T
Yield	619	<0.001	89.18	3.45	1.86
TSS	52.31	0.049	29.27	0.10	0.31
Asc	79.07	<0.001	75.97	0.86	0.93
gs	299.70	<0.001	91.66	4.07	2.02
PN	497.14	<0.001	91.15	4.18	2.05
Chl	145.67	<0.001	73.23	0.76	0.87
LA	185.33	<0.001	80.04	1.09	1.05

Yield, Yield; TSS, soluble solid content; Asc, ascorbic acid content; Chl, chlorophyll content; PN, photosynthetic capacity; g_s, stomatal conductance; LA, leaf area.

Q, The heterogeneity parameters are the weighted sum-of-squared differences between the observed effects and the weighted-average effects; p_q, the test of the null hypothesis; I², the measure of the proportion of observed variance that reflects the real differences in the effect size; T² and T, the measure of the dispersion of the true effect sizes between studies in terms of the scale of the effect size (Hak et al., 2016).