Accupar lp 80 ceptometer

Chlorophyll content, net photosynthesis, transpiration rate, and leave angle of six shoots of each genotype were measured on the fifth to tenth terminal of mature leaves from the base of the shoot at 30 d after infestation. Chlorophyll content (ChlSPAD value) was estimated using a portable chlorophyll meter (CCM-200, Opti-Sciences, Tyngsboro, MA, USA). Light-saturated net photosynthesis was measured with a portable infrared gas analyzer (LI-6200, LI-COR, Lincoln, NE, USA). Transpiration rate was measured with a portable porometer (LI-1600, LI-COR, Lincoln, NE, USA). Leaf angle was measured using an Accupar LP-80 ceptometer (Decagon Devices, NE Hopkins Court, Pullman, WA, USA).

To evaluate whether changes in species diversity and vegetation structure corresponded with canopy light interception, we quantified the fraction of photosynthetically active radiation (fPAR) absorbed by the canopies of each plot at peak LAI in 2016. We used an AccuPAR LP‐80 ceptometer (Decagon Devices Inc) to measure ground‐level PAR along a 2 m × 2 m gridded 400‐m² area within each plot for a total of 100 measurements. Concurrent above‐canopy PAR measurements were obtained from an Apogee SQ‐110 quantum sensor (Apogee Instruments Inc.) positioned on a nearby (< 200 m) meteorological tower, and ground and above‐canopy PAR matched to the closest (≤ 5 min) datum for the derivation of fPAR. Measurements were attempted under clear sky conditions between the hours of 11:30 a.m. and 4:00 p.m. from mid‐July to early August 2016, but intermittent cloud cover in 9 plots forced the omission of 1% – 32% of total PAR measurements in these plots.

Chlorophyll concentration (ChlSPAD) was estimated using a portable chlorophyll content meter CCM-200 (Opti-Sciences, USA). The data collected corresponded to the green color content of a leaf, and its value was equivalent to the amount of light transmitted by the leaf in two regions of the red and infrared wavelengths. The amount of red light absorbed indicated the quantity of chlorophyll, whereas the quantity of light absorbed next to the infrared wavelength was used as an internal reference to compensate for leaf thickness (Torres Netto et al., 2005 (link)). The leaf area index (LAI) was estimated using an Accupar LP-80 ceptometer (Decagon Devices, USA). Due to semi-erect growth habit of Perla Negra and Diacol Capiro, plants were tutored (45 dae) and separated avoiding overlapping between them. Additionally, the analysis where based on segments involved reducing the error based on clumping effects of a canopy. Similar studies on single plants have estimated LAI in greenhouse under similar conditions. (Mushagalusa et al., 2008 (link); Moeller et al., 2014 (link); Mendoza-Pérez et al., 2017 (link)). Finally, three readings per plant were averaged to get the final LAI value. Total water content (H₂Ot) was evaluated by difference of dry and fresh mass.