199 Training System and Photosynthetic Activity of `Perlette' Vines Grown in the Sonoran Desert

Abstract

Table grapes grown in the Sonoran Desert of Mexico are mostly an export commodity directed to early season markets. In order to define the effect on canopy management on light use and berry ripening, `Perlette' vines planted along eastwest rows (typical in such a region) were trained under four systems: slanted pergolas (SP), CIAD, lyre (LY), and T-trellis with open canopies (TTOC). They were compared with traditional closed-canopy T-trellis (TT). Variables evaluated were photosynthetic active radiation (PAR), photosynthesis (PH), stomatal resistance (SR), chlorophyll content (CC), and berry total soluble solids (TSS). At harvest, PAR values for LY, SP, CIAD, TTOD, and TT were 2192, 2076, 1900, 885, and 771 μmol·m-2·s-1, respectively. In the same order, PH at veraison was 12.5, 12.7, 11.0, 10.5, and 5.1 μmol CO2/m2 per s, while in recently harvest vines it decreased to 9, 9, 8.1, 5.1, and 3.7 μmol CO2/m2 per s. SR at veraison was 3.4, 2.6, 2.8, 3.9, and 4.2 s/cm, but, after harvest it was 2.5, 3.5, 2.3, .2.9, and 6.8 s/cm. No significant differences in CC were found among treatments. TSS on 27 Apr. reached 14.9, 15.3, 15.7, 14.5, and 12.2 °Brix; on 29 Apr. they increased to 15.9, 15.5, 16.3, 15.1, and 13.1 °Brix. Based on the above, we demonstrated that canopy management and sunlight cropping represent a useful tool to advance table grape ripening, thus allowing an early harvest and therefore access to the high prices typical of early season markets.