Promotion of root growth by the application of inosine

Figures & data

Figure 1 Dry weight (g plant−1) of the leaves, stems and roots in (a) rice, (b) tomato, (c) sunflower, (d) onion and (e) soybean grown in a hydroponic system with 0 (Control), 7.2, 72 or 373 μmol L−1 of inosine. Error bars indicate the standard error. Different letters denote significant differences in total dry weight using a Tukey’s test (P < 0.05).

Figure 2 Total root length (m plant−1) for (a) rice, (b) tomato, (c) sunflower, (d) onion and (e) soybean grown in a hydroponic system with 0 (Control), 7.2, 72 or 373 μmol L−1 inosine. Error bars indicate the standard error. Different letters denote significant differences using a Tukey’s test (P < 0.05).

Table 1 Complementary data for root hair density (number of root hairs mm−1) in rice, tomato, sunflower and soybean grown in a hydroponic system with 0 (Control), 7.2, 72 or 373 μmol L−1 inosine

Species	Inosine (μmol L^−1)	No. root hairs mm^−1
Rice	0	48 ± 10 a
	7.2	56 ± 8 a
	72	49 ± 5 a
	373	99 ± 14 b
Tomato	0	25 ± 7 a
	7.2	78 ± 15 b
	72	110 ± 13 bc
	373	155 ± 14 c
Sunflower	0	24 ± 6 a
	7.2	52 ± 7 ab
	72	82 ± 8 b
	373	136 ± 13 c
Soybean	0	33 ± 12 a
	7.2	20 ± 10 a
	72	42 ± 13 a
	373	30 ± 11 a
Within each column, values followed by different letters are significantly different based on Tukey’s tests (P < 0.05). Values are mean ± standard error.

Figure 3 Root hair microscopy images (200× magnification) from rice, tomato, sunflower, onion and soybean grown in nutrient solutions with (a) 0, (b) 7.2, (c) 72 and (d) 373 μmol L−1 inosine. The scale bar is 0.5 mm.

Figure 4 (a–c) Rice and (d–f) tomato grown in nutrient solution and in a rhizobox with soil, respectively. (a) Root length in cm plant−1, (b) number of lateral roots per plant and (c) the leaf nitrogen content in mg g−1 of rice grown hydroponically with different concentrations of inosine (0, 72 or 144 μmol L−1). (d) Root length of tomato in m rhizobox−1, (e) root surface area covered in terms of the percentage of the total rhizobox area and (f) the leaf nitrogen content in mg g−1. Error bars indicate the standard error. Different letters denote significant differences using Tukey’s tests (P < 0.05). *P < 0.05; ns, not significant (comparisons between the control measures and the inosine treatments according to Student’s t-tests).

Table 2 Nitrogen content of the leaves, stems and roots (mg g−1) in rice, tomato, onion, sunflower and soybean grown in a hydroponic system with 0 (Control), 7.2, 72 or 373 μmol L−1 of inosine

Species	Inosine (μmol L^−1)	Nitrogen content (mg g^−1)
		Leaves	Stem	Roots
Rice	0	35.0 ± 0.50 a	16.5 ± 0.32 a	13.6 ± 0.19 a
	7.2	36.7 ± 0.77 ab	16.7 ± 0.44 a	15.2 ± 0.32 a
	72	38.1 ± 0.27 b	17.2 ± 0.23 a	17.2 ± 0.27 b
	373	49.0 ± 0.47 c	26.8 ± 0.24 b	30.0 ± 0.93 c
Tomato	0	22.0 ± 0.22 a	13.2 ± 0.17 a	18.3 ± 0.21 a
	7.2	22.8 ± 0.31 a	13.7 ± 0.15 a	18.4 ± 0.22 a
	72	28.0 ± 0.41 b	16.2 ± 0.14 b	25.8 ± 0.88 b
	373	56.3 ± 0.44 c	30.0 ± 0.54 c	51.7 ± 1.48 c
Sunflower	0	28.0 ± 0.30 a	6.4 ± 0.11 a	11.3 ± 0.35 a
	7.2	30.0 ± 0.66 a	6.6 ± 0.12 a	12.4 ± 0.24 a
	72	32.6 ± 0.48 a	6.6 ± 0.12 a	16.4 ± 0.31 b
	373	60.5 ± 2.46 b	32.5 ± 2.21 b	33.0 ± 0.54 c
Onion	0	32.4 ± 0.49 a	21.8 ± 0.8 a	27.7 ± 0.48 a
	7.2	32.1 ± 0.22 a	19.5 ± 0.47 a	25.9 ± 0.42 a
	72	39.4 ± 0.67 b	29.3 ± 0.51 b	36.0 ± 0.3 b
	373	40.6 ± 0.91 b	34.8 ± 1.94 c	49.3 ± 0.93 c
Soybean	0	25.8 ± 0.65 a	11.7 ± 0.14 a	18.7 ± 0.11 a
	7.2	29.1 ± 0.45 b	11.9 ± 0.16 a	19.6 ± 0.18 a
	72	36.5 ± 0.48 c	14.3 ± 0.28 b	22.3 ± 0.09 b
	373	54.1 ± 0.72 d	39.0 ± 0.52 c	36.5 ± 0.48 c
Within each column, values followed by different letters are significantly different based on Tukey’s tests (P < 0.05). Values are mean ± standard error.