The 2009 ASHS Annual Conference

In the Northwest of Mexico pecan vivipary levels are high. The goal of this study was to determine the effect of harvesting date, cultivar, and nut filling on vivipary of pecan trees growing in warm climate. Weather conditions during nut filling are: average high temperatures, 36.4 - 38.6 ºC; average minimum temperatures, 15.0 - 26.8 ºC; and average relative humidity percent, 47 - 69. Harvest date effect on vivipary was obtained from a commercial harvest data during 2003 of a cleaning plant. Vivipary was classified as “sprout” when the embryo activity was big enough that nut shell split occurred at the apex, and as “embryo rot” when this activity just caused change in color and flavor of embryo. Harvest period analyzed was from October 9 through December 4. ‘Wichita’ sprouts varied from 11.9 to 24.1%. The steepest increment occurred from October 9 to October 23. 'Western' had lower sprout level (9.5 to 15.1%). Embryo rot changed from 3.1 to 9.4% in 'Wichita' and from 8.4 to 13.6% in 'Western'. Average levels of vivipary were also recorded during three years. In these years of study, sprout was higher in 'Wichita' (23.4, 19.9, and 19.8 %) than in 'Western' (13.5, 13.9, and 10.9 %). Embryo rot was higher in 'Western' (20.2, 5.5, and 10.8%) than 'Wichita' (12.6, 3.1, 6.3%). Relationship between nut filling and sprout and embryo rot was not significant in 'Western' but in 'Wichita' a negative relationship was found for sprout (r²= 0.53*) and embryo rot (r²= 0.79**). Cultivars, year of harvest, and date of harvest influenced commercial nut quality of pecan trees growing under warm climate. Nut filling affected nut vivipary.