Yield and vivipary of pecan nut (Carya illinoinensis [Wangenh.] K. Koch) in relation to soil moisture

Introduction: Viviparity in pecan nut (Carya illinoinensis [Wangenh.] K. Koch) has increased considerably. This genetic-environmental phenomenon can be controlled with soil moisture management and other quality variables. Objective: To determine the effect of soil moisture content on yield, nut size, kernel percentage and germinated nut on the tree. Materials and methods: Forty-year-old pecan nut trees were irrigated by 40 emitters with an output of 3.2 L.h(-1). From the phenological stage of shell hardening, irrigation time was 4, 6 and 8 h, corresponding to moisture levels of 0.257, 0.327 and 0.380 m(3) of water per m(3) of soil, at depths of 40 to 80 cm. Yield per tree, germinated nut percentage, fruit size and kernel percentage were evaluated during the production cycles of 2016 and 2017 production cycles. Results and discussion: During the two production cycles, when soil moisture level increased from 0.257 to 0.380 m(3).m(-3), nut yield per tree, fruit length and diameter, and kernel percentage increased on average 23.8 %, 25.3 and 10 %, and 1.8 %, respectively; however, vivipary increased 11.2 %, which was reflected in the decrease of commercial pecan nut percentage. Treatments 0.327 and 0.380 m(3).m(-3) had a similar effect (P > 0.05) on these variables. Conclusions: The lower moisture level (0.257 m(3).m(-3)), starting at the kernel filling stage, decreased vivipary and increased commercial kernel percentage.