Distribution of boron and its forms in young “Newhall” navel orange (Citrus sinensis Osb.) plants grafted on two rootstocks in response to deficient and excessive boron

Figures & data

Figure 1. Performance of “Newhall” navel orange plants grafted on trifoliate orange and citrange at the treatment B0 (no boron) after 117 days. Left: citrange, right: trifoliate orange.

Figure 2. Performance of “Newhall” navel orange plants grafted on trifoliate orange and citrange at the treatment B50 (excessive boron) after 117 days. Left: citrange, right: trifoliate orange.

Table 1. Dry mass (grams per plant) of different parts of “Newhall’ navel orange plants grafted on trifoliate orange and citrange with different boron treatments [treatment without boron (B0, no boron), boron concentrations at 0.5 mg L⁻¹ (B05, control treatment) and 5.0 mg L⁻¹ (B50, excessive boron) using boric acid]

Tree tissue	B0		B05		B50
	Citrange	Trifoliate orange	Citrange	Trifoliate orange	Citrange	Trifoliate orange
Mature leaves	4.8 ± 0.4a	3.8 ± 1.4ab	5.4 ± 2.4a	4.8 ± 2.3a	4.9 ± 1.5a	3.5 ± 0.3bc
New leaves	7.4 ± 1.8ab	10.2 ± 1.9a	8.3 ± 1.0a	10.0 ± 2.6a	4.1 ± 0.5cd	5.6 ± 2.7bc
Roots	10.5 ± 0.9bc	12.7 ± 1.2ab	11.9 ± 2.1abc	13.6 ± 1.6a	9.8 ± 1.2cd	10.9 ± 2.7bc
Rootstock's parts	18.5 ± 3.0a	18.7 ± 1.9a	21.0 ± 3.9a	20.4 ± 6.0a	17.4 ± 1.5a	16.8 ± 3.4a
Scion's parts	19.5 ± 3.6a	20.6 ± 1.7a	23.2 ± 7.1a	22.2 ± 4.2a	13.6 ± 2.4b	13.6 ± 3.1b
Whole plant	38.0 ± 6.5abc	39.3 ± 2.4ab	44.2 ± 9.9a	42.6 ± 9.8a	30.9 ± 0.9bc	30.4 ± 4.4cd
Note: Values are means of three replicates ± standard error. Plant parts with different letters are significantly different at P < 0.05.

Table 2. Boron concentration (in mg kg⁻¹) of different parts of “Newhall” navel orange plants grafted on trifoliate orange and citrange with different boron treatments [treatment without boron (B0, no boron), boron concentrations at 0.5 mg L⁻¹ (B05, control treatment) and 5.0 mg L⁻¹ (B50, excessive boron) using boric acid]

	B0		B05		B50
Tree tissue	Citrange	Trifoliate orange	Citrange	Trifoliate orange	Citrange	Trifoliate orange
Roots	22.4 ± 1.0d	22.3 ± 0.5d	25.2 ± 3.4d	41.9 ± 3.0c	51.5 ± 0.8b	62.0 ± 4.3a
Stem of rootstock	32.2 ± 4.3c	43.0 ± 4.7b	33.8 ± 3.7c	46.1 ± 4.9b	48.0 ± 5.8b	62.5 ± 7.9a
Stem of scion	25.4 ± 3.4cd	23.2 ± 1.6d	26.0 ± 2.4cd	27.2 ± 2.5c	31.4 ± 4.7b	37.3 ± 0.9a
Mature leaves	59.8 ± 6.5e	65.3 ± 9.1e	79.1 ± 7.5d	122.7 ± 13.0c	369.9 ± 35.5b	462.3 ± 5.5a
New leaves	101.2 ± 6.5d	138.3 ± 12.6c	140.6 ± 7.1c	212.9 ± 21.4b	712.0 ± 107.9a	674.7 ± 168.6a
Note: Values are means of three replicates ± standard error. Plant parts with different letters are significantly different at P < 0.05.

Figure 3. Boron accumulation (in milligrams per plant) in (A) root, (B) rootstock's parts (root and stem of rootstock), (C) leaves, (D) scion's parts (leaves and stems of scion) and (E) whole plant of “Newhall” navel orange plants grafted on trifoliate orange and citrange with different boron treatments [B0 (no boron), B05 (control treatment) and B50 (excessive boron)]. Values are means of three replicates ± standard error. Bars with different letters are significantly different at P < 0.05.

Figure 4. Fractions (in percentages) of total plant boron content in (A) root, (B) rootstock's parts (root and stem of rootstock), (C) leaves and (D) scion's parts (leaves and stems of scion) of “Newhall” navel orange plants grafted on trifoliate orange and citrange with different boron treatments [B0 (no boron), B05 (control treatment) and B50 (excessive boron)]. Values are means of three replicates ± standard error. Bars with different letters are significantly different at P < 0.05.

Figure 5. Boron utilization index (in g mg⁻¹) of “Newhall” navel orange plants grafted on trifoliate orange and citrange with different boron treatments ([B0 (no boron), B05 (control treatment) and B50 (excessive boron)]. Values are means of three replicates ± standard error. Bars with different letters are significantly different at P < 0.05.

Table 3. Spring-flush leaves boron (B) forms (free B, semi-bound B and bound B) of “Newhall” navel orange plants grafted on trifoliate orange and citrange with different B treatments [treatment without B (B0, no B), boron concentrations at 0.5 mg L⁻¹ (B05, control treatment) and 5.0 mg L⁻¹ (B50, excessive B) using boric acid]

Boron forms	B0		B05		B50
	Citrange	Trifoliate orange	Citrange	Trifoliate orange	Citrange	Trifoliate orange
Free B	1.6 ± 0.1f	2.4 ± 0.2e	3.9 ± 0.3d	6.9 ± 0.3c	16.4 ± 0.8a	8.6 ± 0.4b
Semi-bound B	3.6 ± 0.3e	4.3 ± 0.3cd	4.8 ± 0.2c	3.9 ± 0.3de	17.4 ± 0.8a	7.0 ± 0.3b
Bound B	2.9 ± 0.2d	3.2 ± 0.2d	7.3 ± 0.3b	4.5 ± 0.4c	7.4 ± 0. 6b	9.2 ± 0.6a
Note: Values are means of three replicates ± standard erroe. And B forms with different letters are significantly different at P < 0.05. (Unit: mg kg^−1 fresh weight.)

Figure 6. Relative content of boron forms of “Newhall” navel orange plants grafted on trifoliate orange and citrange with different boron treatments [B0 (no boron), B05 (control treatment) and B50 (excessive boron)]. Values are means of three replicates.