Evaluation of the mitodepressive effect, chromosomal aberrations and nuclear abnormalities induced by urea fertilization in the meristematic tissues of Allium cepa L.

Figures & data

Table 1. Variance analysis (ANOVA) of studied traits of Allium cepa L.

Traits	SS	df	MS	F
Mitotic index (MI%)	4336.56	6	722.76	82.08*
Total aberrant cells	467,746.3	6	77,957.71	809.65*

Abbreviations: SS, sum of squares; df, degrees of freedom; MS, mean sum of squares; F, F statistic test.

*Significant at p < 0.05.

Table 2. Effect of different concentrations of urea on cytological parameters in the meristematic tissues of Allium cepa L.

Variant/concentration	Analysed cells	MI ± SE %	I	Mit	P	M	A	T
Control	500	44.2 ± 2.43	279	221	48	39	53	81
V1/100 ppm	500	31.2 ± 1.27*	344	156	28	24	30	74
V2/500 ppm	500	26.2 ± 1.73*	369	131	36	12	25	61
V3/1000 ppm	500	12.4 ± 2.54*	438	62	20	6	8	28
V4/5000 ppm	500	8.2 ± 0.11*	459	41	13	4	6	18
V5/10,000 ppm	500	4.6 ± 1.5*	477	23	7	3	2	11
V6/20,000 ppm	500	3.4 ± 1.16*	483	17	5	1	3	8
LSD 5%		2,42

Abbreviations: MI%, mitotic index; I, number of cells in interphase; Mit, number of cells in mitosis; P, number of cells in prophase; M, number of cells in metaphase; A, number of cells in anaphase; T, number of cells in telophase; SE, standard error.

*Significant at p < 0.05.

Table 3. Total number of aberrant cells (cells with nuclear anomalies and cells with chromosomal aberrations) identified in meristematic tissues of Allium cepa L. treated with different urea concentrations.

Variant/concentration	Total aberrant cells (X ± SE)	CB	CM	MN	S	L	C-M
Control	4 ± 0.66	3	-	-	-	-	1
V1/100 ppm	99 ± 5.78*	24	15	-	23	28	9
V2/500 ppm	118 ± 5.78*	31	18	-	26	29	14
V3/1000 ppm	139 ± 6.35*	38	21	-	28	36	16
V4/5000 ppm	200 ± 6.93*	46	32	10	37	47	28
V5/10,000 ppm	384 ± 3.47*	81	68	51	56	69	59
V6/20,000 ppm	451 ± 7.51*	109	87	60	64	70	61
LSD 5%	17.22

Abbreviations: CB, binucleated cells; CM, multinucleated cells; MN, cells with micronuclei; S, sticky chromosomes; L, laggards chromosomes; C-M, C-mitosis; SE, standard error.

*Significant at p < 0.05.

Figure 1. The relative aberrant cell rate (RAR%) in meristematic tissues of Allium cepa L. treated with different urea concentrations (ppm).

Figure 2. Some chromosomal aberrations induced by exposure to different concentrations of urea in the meristematic tissues of Allium cepa L.: (a) laggard chromosome; (b, c) sticky chromosomes; (d) C-mitosis.

Figure 3. Some interphase nuclear anomalies induced by exposure to different concentration of urea in meristematic tissues of Allium cepa: (a) binucleated cells; (b) multinucleated cells with ghost nuclei; (c) cell with three micronuclei; (d) cell with nine micronuclei.

Table 4. Usual concentrations of urea in the solubilized form to the main crop plants.

Culture plant	Application conditions	Concentration (%)
Wheat and barley	Stage of the stalks formation, temperature 15°C	8
	Stage of the stalks formation, temperature 20°C	6
Maize	During the vegetation period, at the stage of 6–8 leaves	2,5
Sunflower	Up to the stage of developing floral button	2,5
Fruit trees	Before the first winter treatment	5
Vegetables	During the vegetation period	2,5