MICROMORPHOLOGICAL OBSERVATION OF EUCALYPTUS SEEDS, MULTIVARIATE STATISTICAL ANALYSES AND MODELING OF THEIR GERMINATION UNDER SALT STRESS AND OSMOTIC CONSTRAINT

MECHERGUI, KAOUTHER; JAOUADI, WAHBI; NAGHMOUCHI, SOUHEILA; ALSUBEIE, MOODI; Khouja, Mohamed Larbi

doi:10.1590/01047760201925022635

ABSTRACT

Micromorphological characters including surface, length and width of seeds were recorded for 19 species of Eucalyptus (Myrtaceae) using stereomicroscope to determine the importance of seed morphological characters as an additional tool for identification.With the aim of selecting and valorizing abiotic-stress-tolerant species with landscape and industrial values and would be a potential solution for valorizing dry arid area and development of land degradation, we launched the assessment of the performance of five Eucalyptus species (E. torquata, E. sargenti, E. gillii, E. gomphocephala x E. cornuta and E. microtheca) under salinity and osmotic potential constraints. Several NaCl concentrations (0, 3, 6, 9, 12, and 15 g.L^-1) and several osmotic potentials (0, -0.03, -0.1, -0.7, -1 and -1.6 MPa) were applied to seeds cultivated in petri dishes for a period of one month. Germination rates, means time of germination and coefficent of velocity were evaluated to better understand the salt stress and osmotic potential effect on germination. Univariate and multivariate analyses were used to identify the major characteristics pertaining to salinity tolerance. Modeling of germination under both constraints saline and osmotic stress is carried out to predict the behavior of the species. The hybrid E. gomphocephala x E. cornuta was more tolerant to salt stress (15 % at 12 g.L^-1) and osmotic potential (61 % at -1.6 MPa) than the others species of Eucalyptus; it showed a higher germination percentage under all tested potentials, when compared to the not hybrid species of Eucalyptus. Our analyses of seeds morphology revealed that the observations shown diversity of morphological characters in seeds. Area, length and width of seeds vary significantly between species of Eucalyptus. Micromorphological characters can provide basis for classification and delimitation of genus Eucalyptus.

Keywords:
Eucalyptus; Seeds morphology trait; Salt stress; Osmotic potentials; Principal component analysis; Modeling

[1] + jaouadiwahbi@gmail.com

Parameters of seeds	Df	Sum	Sq	F value	Pr(>F)
Area of seeds	18	276.71	15.373	65.02	<2e-16 ***
Lengh of seeds	18	72.39	4.022	50.74	<2e-16 ***
Widh of seeds	18	26.30	1.4612	28.34	<2e-16 ***

	Area of seeds (mm²)			Lengh of seeds (mm)			Widh of seeds (mm)
	mean	SD	CV	mean	SD	CV	mean	SD	CV
E. accedens	1.42	0.25	0.17	1.50	0.19	0.12	1.20	0.12	0.10
E. angulosa	3.65	0.66	0.18	2.69	0.34	0.12	1.84	0.29	0.15
E. burracoppinensis	3.40	0.37	0.11	2.58	0.31	0.11	1.82	0.22	0.12
E. cornuta	1.53	0.19	0.12	1.46	0.20	0.14	1.14	0.26	0.22
E. diversifolia	3.01	0.46	0.15	2.22	0.22	0.09	1.74	0.28	0.16
E. dumosa	3.52	0.52	0.14	2.70	0.41	0.15	1.82	0.22	0.12
E. gillii	2.25	0.35	0.15	2.01	0.26	0.13	1.49	0.15	0.10
E. gomphocephala	1.45	0.72	0.50	1.55	0.41	0.26	1.24	0.28	0.23
E. lehmannii	2.17	0.43	0.19	1.92	0.23	0.11	1.48	0.18	0.12
E. leucoxylon	1.49	0.41	0.27	1.50	0.23	0.15	1.19	0.18	0.15
E. microtheca	1.71	0.28	0.16	1.88	0.20	0.11	1.27	0.23	0.18
E. perriniana	2.30	0.51	0.22	2.02	0.19	0.09	1.56	0.27	0.17
E. pimpiniana	3.16	0.57	0.15	2.55	0.26	0.10	1.82	0.30	0.16
E. platypus	1.62	0.16	0.10	1.63	0.13	0.08	1.33	0.17	0.13
E. saligna	1.32	0.32	0.24	1.61	0.27	0.17	1.09	0.11	0.10
E. sargenti	1.17	0.14	0.12	1.35	0.15	0.11	1.13	0.11	0.09
E. stoatei	1.51	0.28	0.18	1.61	0.24	0.15	1.31	0.20	0.15
E. torquata	3.16	0.68	0.21	2.36	0.35	0.15	1.74	0.21	0.12
E. viminalis	2.31	0.95	0.41	2.02	0.42	0.21	1.47	0.28	0.19

Species	Parameters	0 g.l^-1	3g.l^-1	6g.l^-1	9g.l^-1	12g.l^-1	15g.l^-1	Pr(>F)
Eucalyptus Sargenti	Germination rate (%)	93±8.36b	69±27.70b	20±17.32a	12±9.08a	6±4.18a	1±2.23a	0.000***
	Means time of germination (Days)	6.52±0.77ab	8.45±1.69ab	15.44±2.15b	13.46±9.13ab	13.80±7.88ab	3.40±7.60a	0.0227*
	Velocity index	15.52±2.09c	12.24±2.57c	6.59±1.06b	5.19±3.43ab	4.67±2.66ab	1.17±2.62a	0.000***
Eycalyptus Gompho-cornuta	Germination rate (%)	99±5.47d	73±9.74cd	49±33.42bc	16±12.94ab	15±28.06ab	3±4.47a	0.000***
	Means time of germination (Days)	6.47±2.38a	6.72±1.11a	10.85±3.78a	8.45±3.37a	5.44±5.61a	6.50±8.90a	0.390
	Velocity index	16.79±4.65b	15.14±2.08b	10.33±4.12ab	8.61±6.54ab	7.63±8.29ab	2.46±3.37a	0.003**
Eycalyptus Microtheca	Germination rate (%)	93±5.70c	41±17.10b	29±16.73b	7±4.47a	4±6.51a	3±6.70a	0.000***
	Means time of germination (Days)	13.30±3.96a	12.02±1.66a	12.36±2.05a	13.10±7.87a	9.33±12.81a	3.80±9.49a	0.320
	Velocity index	8.02±2.40b	8.45±1.25b	8.29±1.54b	5.03±2.99ab	1.72±2.36a	1.05±2.35a	0.000***
Eycalyptus Gillii	Germination rate (%)	99±2.23d	43±12.54c	33±36.50bc	8±13ab	4±4.18ab	0.00±000a	0.000***
	Means time of germination (Days)	7.76±1.41ab	15.21±4.27b	18.26±4.64b	8.36±11.60ab	8.70±8.31ab	0.00±000a	0.002**
	Velocity index	13.17±2.07d	7.23±2.98c	5.75±1.36bc	1.97±2.69ab	4.33±4.19ac	0.00±000a	0.000***
Eycalyptus Torquata	Germination rate (%)	77±27.74b	52±19.23b	17±9.08a	10±5.00a	7±4.47a	2±2.73a	0.000***
	Means time of germination (Days)	7.39±1.10bc	7.84±0.87bc	9.39±2.66c	9.93±2.41c	4.40±3.92ab	2±2.82a	0.000***
	Velocity index	13.78±2.23a	12.98±1.46a	11.38±3.28a	10.48±2.16a	18.87±14.68a	8.33±11.78a	0.420

Species	Parameters	0 MPa	-0.03 MPa	-0.1 MPa	-0.7 MPa	-1 MPa	-1.6 MPa	Pr(>F)
Eucalyptus Torquata	Germination rate (%)	90±10.00c	96±4.18c	72±21.67bc	57±12.54b	19±14.74a	9±4.18a	0.000***
	Means time of germination (Days)	6.58±1.60a	7.81±1.21a	7.91±1.63a	5.59±1.11a	13.70±11.27a	8.53±8.81a	0.374
	Velocity index	16.03±4.39a	13.09±2.41a	13.06±2.62a	18.43±3.64a	12.77±8.63a	20.16±11.70a	0.356
Eucalyptus Sergenti	Germination rate (%)	84±17.10b	91±5.47b	78±15.24b	60±11.72ab	59±39.27ab	27±27.52a	0.000***
	Means time of germination (Days)	5.66±0.95a	5.10±1.41a	5.40±1.01a	5.74±1.33a	4.74±1.49a	10.15±9.97a	0.370
	Velocity index	18.04±2.83a	20.81±5.75a	19.01±3.29a	19.21±4.94a	22.86±7.31a	19.01±15.10a	0.934
Eucalyptu Gillii	Germination rate (%)	85±22.63c	87±13.50c	73±16.04bc	32±21.96a	45±15.81ab	24±23.82a	0.000***
	Means time of germination (Days)	9.83±1.56a	7.34±0.85a	7.50±1.74a	7.26±1.83a	6.76±1.53a	13.98±8.74a	0.051
	Velocity index	10.39±1.73a	13.76±1.59a	13.85±2.92a	14.43±3.28a	15.18±2.47a	10.23±6.47a	0.140
Eucalyptus Gompho-cornuta	Germination rate (%)	88±11.51a	92±11.51a	82±14.40a	78±24.13a	72±27.74a	61±28.56a	0.238
	Means time of germination (Days)	20±3.06a	17.84±2.91a	16.91±3.19a	16.44±3.67a	18.03±4.23a	17.10±4.00a	0.674
	Velocity index	8.58±2.27a	10.67±1.78a	11.87±1.29a	10.23±2.34a	14.29±1.98a	11.69±4.41a	0.618
Eucalyptus Microtheca	Germination rate (%)	77±16.04c	67±15.24c	59±14.74bc	37±4.47b	35±16.20b	9±4.18a	0.000***
	Means time of germination (Days)	6.47±1.45a	7.96±1.42a	8.46±2.20a	5.95±0.98a	7.40±0.56a	5.33±2.29a	0.037 *
	Velocity index	16.19±4.21ab	12.90±2.45ab	12.48±3.25a	17.24±3.32ab	13.57±1.02ab	21.83±9.18b	0.035 *

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MICROMORPHOLOGICAL OBSERVATION OF EUCALYPTUS SEEDS, MULTIVARIATE STATISTICAL ANALYSES AND MODELING OF THEIR GERMINATION UNDER SALT STRESS AND OSMOTIC CONSTRAINT

ABSTRACT