Table 5.

Summary of stepwise multiple regression equations for metal concentrations in the grains of three crop species as function of soil total or extractable metal concentrations and soil properties.

	Equation	r2	radj2	pvalue
Brassica juncea/Rape (n = 36)	Log10[grain] − (Cu)* = 0.304 + 0.146 Log10[total] − (Cu)**	0.283	0.262	0.001
	Log10[grain] − (Cd) =  − 1.189 + 0.158Log10[EDTA] − (Cd)	0.135	0.109	0.028
	Log10[grain] − (Mn) = 1.221 + 0.234 Log10[DTPA] − (Mn)	0.306	0.286	< 0.001
Triticum aestivum/Wheat (n = 25)	Log10[grain] − (Cu) = 0.655 + 0.096Log10[total] − (Cu)	0.408	0.382	0.001
	Log10[grain] − (Cu) = 1.192 + 0.144Log10[total] − (Cu) − 0.318 Log10(AK)	0.560	0.520	< 0.001
	Log10[grain] − (Zn) = 1.686 + 0.061Log10[NH4OAC] − (Zn)	0.285	0.254	0.006
	Log10[grain] − (Zn) = 1.338 + 0.046Log10[NH4OAC] − (Zn) + 0.559 Log10[total] − (Zn)	0.415	0.362	0.003
	Log10[grain] − (Cd) =  − 0.404 + 0.441Log10[DTPA] − (Cd)	0.330	0.301	0.003
	Log10[grain] − (Cd) = 0.632 + 0.601Log10[DTPA] − (Cd) − 0.145pH	0.563	0.524	< 0.001
	Log10[grain] − (Mn) = 1.491 + 0.183Log10[NH4OAC] − (Mn)	0.674	0.659	< 0.001
	Log10[grain] − (Mn) = 1.644 + 0.273Log10[NH4OAC] − (Mn) − 0.167 Log10[DTPA] − (Mn)	0.732	0.708	< 0.001
Oryza sativa/rice (n = 20)	Log10[grain] − (Cu) = 0.186 + 0.074 pH	0.285	0.246	0.015
	Log10[grain] − (Zn) = 1.745–0.199 Log10(AK)	0.228	0.185	0.036

*: [grain] − (Cu) means Cu concentrations in grains; **: [total] − (Cu) means total Cu concentrations in soils.