Lysimeter measurements of nocturnal and diurnal grapevine transpiration: Effect of soil water content, and phenology

Abstract

An experiment was carried out in a semi-arid area of Spain (Albacete) with the objective of quantifying the transpiration of grapevine cv. Tempranillo. Measurements of transpiration were taken in a weighing lysimeter over five years (2012–2016); the soil surface was covered with a waterproof canvas to avoid the evaporative component of evapotranspiration. The sample frequency was 1 s, and a mean value was recorded with a datalogger (CR10X, Campbell Scientific) every 15 min, which allowed for measuring the transpiration every quarter of an hour and therefore identify night-time (Enight) and daytime transpiration (Eday). The results show values of Enight between 3 % of total daily transpiration, in the days with the highest soil water content, and 35 %, in the days in which the value of Eday and the soil water content were very low; although most days it was 12 %. We highlight the Enight in the period after sunset more than we do that in predawn, although in this last period, it was higher close to sunrise. Finally, Enight was analysed throughout the growing season, and from veraison to harvest was the period with the highest values.