Yield and Quality of Tobacco Grown with Supplementary Irrigation1

Abstract

AbstractPresently in Cyprus, tobacco (Nicotiana tabacumL.) is grown under supplementary irrigation with water high in CI. The present study sought to investigate the irrigation/yield relationship and the attendant concentration of CI and other constituents in the leaves. In three experiments in which one to six irrigations were tested, maximum evapotranspiration (ET) determined by the soil water balance method was reached 40 to 50 days after planting, and equaled evaporation from a screened Class A pan. The ET started declining just before the first leaf harvest, even though soil water was adequate. However, since soil water became limiting soon afterwards, the course of potential ET could not be followed. From the second leaf harvest until the end of the season, ET was very low (< 1 mm/day). Fresh yield increased from 12 Mg/ha with 60 mm irrigation to 28 Mg/ha with 360 mm irrigation, the highest amount tested. In contrast, dry matter yield only increased from 2.3 to 4.2 Mg/ha, respectively. Moreover, midrib material increased from 20% with 60 mm irrigation to 30% of the total leaf dry matter with 300 mm irrigation. Concentration of CI for the whole leaf increased from about 2% with 60 mm irrigation to 3% with 300 mm irrigation (disregarding the last sampling). Concentration of K decreased from 4 to 2% between the first and the third harvest and in one experiment it tended to increase with irrigation. Leaf P increased from about 0.1 with 60 mm irrigation to 0.2% with 180 mm irrigation. The burn rate of laminae, determined in one experiment, increased with irrigation, even though CI also increased.