Table 2.

Greenness index (SPAD).

Object	C0	Cd	Co
Control	35.988 ab	21.625 d–f	4.450 g
Molecular sieve	34.713 a	29.563 bc	28.313 b–d
Halloysite	38.638 a	19.588 ef	21.325 d–f
Sepiolite	35.175 ab	25.413 c–e	22.963 c–e
Expanded clay	35.238 ab	24.275 c–e	14.563 f
Biochar	39.138 a	22.975 c–e	19.438 ef
Zeolite	33.488 a	20.213 ef	14.525 f

Homogeneous groups denoted with letters (^a–f).