Towards estimating shade response of bermudagrass (<i>Cynodon</i> spp.) using field-based photosynthetic properties

Jonathon L. Fox; David Jespersen; Lisa L. Baxter; John L. Snider; Marc W. van Iersel; Brian M. Schwartz; Jonathon L. Fox; David Jespersen; Lisa L. Baxter; John L. Snider; Marc W. van Iersel; Brian M. Schwartz

doi:10.48130/GR-2022-0003

Response	LCP^†	фCO₂	R_d	CC	F_v/F_m
Response	(μmol m⁻² s⁻¹)			(mg m⁻²)	F_v/F_m
Month
Aug. 2016	248.6	0.0114	1.7a^‡	407.9	0.7885
Oct. 2016	211.4	0.0094	1.3b	469.4	0.7613
Apr. 2017	141.2	0.0086	1.4b	421.3	0.7513
May 2017	110.1	0.0120	1.1b	505.0	0.6993
Jun. 2017	114.7	0.0147	1.1b	447.9	0.7310
Sep. 2017	72.7	0.0093	0.7c	449.9	0.7082
Genotype
11-T-56	138.7	0.0711	1.3	438.0b	0.7510
Tifway	160.8	0.1578	1.7	467.7a	0.7370
CV^§	19.7	41.9	23.8	7.9	5.7
^† LCP: light compensation point, фCO_2: quantum yield, R_d: dark respiration rate, CC: chlorophyll content, F_v/F_m: chlorophyll fluorescence ^‡ Least square means within each canopy characteristic and response followed by different letters differ according to Fisher's LSD test (P ≤ 0.05) ^§ CV: Coefficient of Variation

Table 1.

Mean light compensation point, quantum yield, dark respiration rate, chlorophyll content, and chlorophyll fluorescence of two bermudagrass genotypes grown in full-sun during 2016 and 2017 in Tifton, GA, USA. Data are pooled across replications.

Genotype	May	July	August	CV^†
	Light compensation point (µmol m⁻² s⁻¹)
11-T-56	63.1b^‡	211.2	273.9	5.6
Tifway	76.9a	248.9	267.7	5.6
	Chlorophyll content (mg m⁻²)
11-T-56	553.5a	390.0	374.8	9.6
Tifway	383.5b	397.5	379.5	9.6
	Chlorophyll fluorescence
11-T-56	0.7436a	0.7301	0.6358	5.4
Tifway	0.5490b	0.7625	0.6290	5.4
^† CV: Coefficient of Variation ^‡ Least square means within each response and month followed by different letters differ according to Fisher's LSD test (P ≤ 0.05)

Table 2.

Mean light compensation point, chlorophyll content, and chlorophyll fluorescence of two bermudagrass genotypes grown in full-sun during 2018 in Tifton, GA, USA. Data are pooled across replications.

Genotype	May	July	August	CV^†
	Light compensation point (µmol m⁻² s⁻¹)
11-T-56	2.6b^‡	20.8	64.8	14.8
Tifway	57.6a	72.2	65.8	14.8
^† CV: Coefficient of Variation ^‡ Least square means within each month followed by different letters differ according to Fisher's LSD test (P ≤ 0.05)

Table 3.

Mean light compensation point of two bermudagrass genotypes grown under 73% shade during 2018 in Tifton, GA, USA. Data are pooled across replications.

Response	May	July	August	CV^†
Quantum yield, (µmol m⁻² s⁻¹)	0.0096	0.0095	0.0118	8.3
Dark respiration rate, (µmol m⁻² s⁻¹)	0.8b^‡	2.4a	2.7a	10.9
^† CV: Coefficient of Variation ^‡ Least square means within each response followed by different letters differ according to Fisher's LSD test (P ≤ 0.05)

Table 4.

Mean quantum yield and dark respiration rate recorded on bermudagrass grown in full-sun during three sampling dates in 2018 in Tifton, GA, USA. Data are pooled across replications and two bermudagrass genotypes, Tifway and experimental number 11-T-56.

Response	Genotype		CV^†
Response	11-T-56	Tifway	CV^†
Quantum yield, (µmol m⁻² s⁻¹)	0.0185	0.0167	14.6
Dark respiration rate, (µmol m⁻² s⁻¹)	0.6	0.4	18.1
Chlorophyll content, (mg m⁻²)	404.1	396.6	8.0
Chlorophyll fluorescence^‡	0.7376a^§	0.6779b	2.1
^† CV: Coefficient of Variation ^‡ Chlorophyll fluorescence could only be measured on one day (May) out of the growing season because of the lack of ground cover ^§ Least square means within each response followed by different letters differ according to Fisher's LSD test (P ≤ 0.05)

Table 5.

Mean quantum yield, dark respiration rate, chlorophyll content, and chlorophyll fluorescence of two bermudagrass genotypes grown under 73% shade during 2018 in Tifton, GA, USA. Data are pooled across replications and month.