Effects of water level changes on the morphological and physiology of the submerged macrophyte Vallisneria natans

Figures & data

Figure 1. Water temperature and air temperature during the experiment.

Figure 2. The changes of underwater light in experiment.

Figure 3. Schematic diagram of experiment design.

Figure 4. Effect of water level change on the plant height of V. natans. Different capital letters indicate the difference between the same change rate and different test times, and different lowercase letters indicate the difference between the same test time and different change rates.

Table 1. Result of two-way analysis of variance (ANOVA) testing for main effects of water level change, time, and their interactions on V. natans (F-value).

Type	Change rate	Test time	Change rate × Test time
Rising water level
Plant height	23.13**	179.147**	4.233*
Blades number	4.36**	54.942***	3.017 ^ns
Chl a	106.82**	339.466**	105.54**
Chl b	93.243*	267.636*	54.307 ^ns
Chl a + b	90.008**	277.318**	65.703**
Car	144.544*	1014.313**	185.816**
SP	7.875***	67.110**	25.344**
SS	38.446*	425.935**	25.313*
Root activity	19.144**	57.321*	5.305 ^ns
AGB	85.689***	7.951**	0.948**
BGB	84.832***	7.032***	0.893***
Declining water level
Plant height	29.989***	431.315***	7.310 **
Blades number	4.218***	52.827**	1.780 ^ns
Chl a	131.147*	488.681***	110.31**
Chl b	66.268**	663.394*	84.384*
Chl a + b	90.318**	439.368**	78.268**
Car	196.472 ^ns	450.785**	129.112*
SP	8.873**	89.416*	8.504 ^ns
SS	6.839*	112.819***	5.342*
Root activity	14.365**	741.069***	16.335**
AGB	82.143**	7.597**	0.922**
BGB	86.169***	6.805*	0.88**

Chl a: chlorophyll a, Chl b: chlorophyll b, Chla + b: chlorophyll a + b, Car: carotenoid, SP: soluble protein, SS: soluble sugar.

*** Means P < 0.001, **means P < 0.01, *means P < 0.05, ns means P > 0.05.

Figure 5. Effect of water level change on the number of blades of V. natans. Different capital letters indicate the difference between the same change rate and different test times, and different lowercase letters indicate the difference between the same test time and different change rates.

Figure 6. Effect of water level change on the Root activity of V. natans. Different capital letters indicate the difference between the same change rate and different test times, and different lowercase letters indicate the difference between the same test time and different change rates.

Figure 7. Effect of water level change on the biomass of V. natans. AGB: above-ground biomass. BGB: below-ground biomass. Different capital letters indicate the difference between the same change rate and different test times, and different lowercase letters indicate the difference between the same test time and different change rates.

Figure 8. Effect of water level change on chlorophyll a (Chl a) of V. natans. Different capital letters indicate the difference between the same change rate and different test times, and different lowercase letters indicate the difference between the same test time and different change rates.

Figure 9. Effect of water level change on chlorophyll b (Chl b) of V. natans. Different capital letters indicate the difference between the same change rate and different test times, and different lowercase letters indicate the difference between the same test time and different change rates.

Figure 10. Effect of water level change on chlorophyll (a + b) (Chl a + b) of V. natans. Different capital letters indicate the difference between the same change rate and different test times, and different lowercase letters indicate the difference between the same test time and different change rates.

Figure 11. Effect of water level changes on carotenoid (Car) of V. natans. Different capital letters indicate the difference between the same change rate and different test times, and different lowercase letters indicate the difference between the same test time and different change rates.

Figure 12. Effect of water level changes on soluble protein (SP) content of V. natans. Different capital letters indicate the difference between the same change rate and different test times, and different lowercase letters indicate the difference between the same test time and different change rates.

Figure 13. Effect of water level change on soluble sugar (SS) content of V. natans. Different capital letters indicate the difference between the same change rate and different test times, and different lowercase letters indicate the difference between the same test time and different change rates.

Table 2. Correlation analysis of morphological and physiological indexes of V. natans.

	SS	SP	Plant height	Blades number	Chl a	Chl b	Chl (a + b)	Car	Root activity
SS	1
SP	0.595**	1
Plant height	0.384**	0.353**	1
Blades number	0.269**	0.372**	0.587**	1
Chl a	0.228*	0.052	−0.019	−0.159	1
Chl b	0.199	0.163	0.019	−0.050	0.739**	1
Chl (a + b)	0.232*	0.092	−0.007	−0.133	0.974**	0.872**	1
Car	0.062	−0.031	−0.037	−0.138	0.704**	0.277**	0.604**	1
Root activity	0.438**	0.355**	0.724**	0.684**	−0.067	−0.057	−0.068	−0.030	1

Chl a: chlorophyll a, Chl b: chlorophyll b, Chl (a + b): chlorophyll (a + b), Car: carotenoid, SP: soluble protein, SS: soluble sugar.

* Significantly correlation at 0.05 (two-sided).

** Significantly correlation at 0.01 (two-sided).