Seasonal dynamics of lettuce growth on different electrical conductivity under a nutrient film technique hydroponic system

Bikash Adhikari; Omolayo J. Olorunwa; Jeff C. Wilson; T. Casey Barickman; Bikash Adhikari; Omolayo J. Olorunwa; Jeff C. Wilson; T. Casey Barickman

doi:10.48130/tihort-0024-0015

Figures (6) Tables (2)

Figure 1.
Effect of different electrical conductivity (EC) treatments (0.5 mS·cm⁻¹, 1.0 mS mS·cm⁻¹, 2.0 mS·cm⁻¹, and 4.0 mS·cm⁻¹) on lettuce fresh mass (FM) at different growth seasons of 2022−2023 (Summer 2022, Winter 2022, and Spring 2023). Data represents ± SE (n = 12). Different letters indicate significant differences at p < 0.05.
Figure 2.
Effect of different electrical conductivity (EC) treatments (0.5 mS·cm⁻¹, 1.0 mS·cm⁻¹, 2.0 mS·cm⁻¹, and 4.0 mS·cm⁻¹) on lettuce dry mass (DM) at different growth seasons of 2022−2023 (Summer 2022, Winter 2022, and Spring 2023). Data represents ± SE (n = 12). Different letters indicate significant differences at p < 0.05.
Figure 3.
Effect of different electrical conductivity (EC) treatments (0.5 mS·cm⁻¹, 1.0 mS·cm⁻¹, 2.0 mS·cm⁻¹, and 4.0 mS·cm⁻¹) on lettuce stomatal conductance (g_s) at different growth seasons of 2022−2023 (Summer 2022, Winter 2022, and Spring 2023). Data represents ± SE (n = 12). Different letters indicate significant differences at p < 0.05.
Figure 4.
Effect of different electrical conductivity (EC) treatments (0.5 mS·cm⁻¹, 1.0 mS·cm⁻¹, 2.0 mS·cm⁻¹, and 4.0 mS·cm⁻¹) on lettuce transpiration rate (E) at different growth seasons of 2022−2023 (Summer 2022, Winter 2022, and Spring 2023). Data represents ± SE (n = 12). Different letters indicate significant differences at p < 0.05.
Figure 5.
Effect of different electrical conductivity (EC) treatments (0.5 mS·cm⁻¹, 1.0 mS·cm⁻¹, 2.0 mS·cm⁻¹, and 4.0 mS·cm⁻¹) on lettuce leaf temperature (T_leaf) at different growth seasons of 2022−2023 (Summer 2022, Winter 2022, and Spring 2023). Data represents ± SE (n = 12). Different letters indicate significant differences at p < 0.05.
Figure 6.
Bubble plot showing the ranking based on the average values for physiology (g_s, E, Fs. Fm', PhiPS2, ETR, and T_leaf) and biomass (fresh and dry mass) of lettuce subjected to different electrical conductivity (EC) treatments (0.5 mS·cm⁻¹, 1.0 mS·cm⁻¹, 2.0 mS·cm⁻¹, and 4.0 mS·cm⁻¹) at different growth seasons of 2022−2023 (Summer 2022, Winter 2022, and Spring 2023). The traits with a largest bubble size (yellow color) indicates the higher values of that traits and smallest bubble size 1 (dark blue color) indicates the lowest values of that traits for a particular EC at a specific growing season.

Concentration	5-11-26 (g)	15.5-0-0 (g)	EC (dS·m⁻¹ or mS·cm⁻¹)	Nitrogen (ppm)	Calcium (ppm)
200%	184.27	121.9	3.8−4.4	300	232
100%	92.13	60.95	1.9−2.2	150	116
50%	46.06	30.47	0.9−1.1	75	58
25%	23.03	15.23	0.45−0.6	37.5	29

Table 1.

Electrical conductivity of different nutrient treatment concentrations and their nitrogen and calcium content.

	Season (S)	Treatment (T)	T*S	0.5	1.0	2.0	4.0
Fs	Summer	**	***	82.27 ± 6.43^e	132.48 ± 13.18^b	130.6 ± 11.65^b	133.35 ± 13.88^b
	Winter	*		148.6 ± 7.01^b	160.85 ± 8.6^a	161.43 ± 9.12^a	174.39 ± 17.43^a
	Spring	**		101.55 ± 3.14^d	112.17 ± 1.48^c	102.96 ± 4.36^d	114.37 ± 2.18^c
Fm'	Summer	*	**	249.13 ± 35.03^d	353.17 ± 19.64^c	367.57 ± 11.27^c	295.42 ± 27.26^d
	Winter	*		375.98 ± 13.59^bc	403.11 ± 39.16^a	370.49 ± 17.93^c	362.78 ± 23.01^bc
	Spring	**		405.95 ± 8.56^ab	426.41 ± 8.54^a	431.55 ± 7.55^a	405.23 ± 8.01^ab
PhiPS2	Summer	*	*	0.58 ± 0.05^b	0.6 ± 0.04^b	0.63 ± 0.03^b	0.51 ± 0.04^d
	Winter	*		0.6 ± 0.01^b	0.57 ± 0.03^bc	0.55 ± 0.02^c	0.52 ± 0.02^d
	Spring	NS		0.74 ± 0.01^a	0.73 ± 0.01^a	0.76 ± 0.01^a	0.71 ± 0.01^a
ETR	Summer	*	**	89.92 ± 15.53^a	130.49 ± 19.13^b	143.75 ± 24.21^b	125.33 ± 24.51^bc
	Winter	**		126.81 ± 6.14^c	139.02 ± 8.99^b	140.45 ± 6.71^b	169.95 ± 10.22^a
	Spring	**		48.14 ± 1.66^e	59.03 ± 2.32^d	22.55 ± 2.41^f	53.72 ± 5.86^d
The values represent Mean ± SE (n = 12). NS, , , ** indicate non-significant or significant at p < 0.05, 0.01, 0.001, respectively. Different superscript letters indicate significant treatment effects of different EC treatments throughout the different seasons using Tukey HSD at p < 0.05. Fs = Steady state fluorescence; Fm'= light-adapted maximal fluorescence; PhiPS2 = quantum yield of photosystem II calculated using fluorescence; and ETR (μmol·s⁻¹) = electron transport rate.

Table 2.

The chlorophyll fluorescence response of lettuce under different electrical conductivity (EC) treatments (0.5 mS·cm⁻¹, 1.0 mS·cm⁻¹, 2.0 mS·cm⁻¹, and 4.0 mS·cm⁻¹) at different growth seasons of 2022−2023 (Summer 2022, Winter 2022, and Spring 2023).