The influence of drip or furrow irrigation on yield and quality of Burley tobacco under saline conditions.

Irrigation methods are critical to alleviate salinity problems in Mediterranean areas, where saline waters are frequently used to irrigate crops. Field experiments were conducted on Burley tobacco ('Nicotiana tabacum' L.) cv. C104 in Southern Italy for two years to compare drip versus furrow irrigation, in which waters of increasing salinity were used. Two irrigation methods (drip and furrow) and six irrigation treatments [rainfed control (RC), and fully-irrigated with water having an electrical conductivity (ECw) of 0.5 (normal water, NW), 2.5 (saline water, SW1), 5 (SW2), 10 (SW3), and 15 dS m-1 (SW4)] were factorially combined. Irrigation water use efficiency (IWUE, kg ha-1 mm-1), soil salt accumulation and soil moisture were measured for each treatment combination. Over the growing season the electrical conductivity of soil (ECe) across the 0.6 m soil's top profile increased with increasing salinity of the irrigation water but more in drip- than furrow-irrigated plots [0.177 and 0.105 dS m-1 ECe (dS m-1 ECw)-1, respectively, averaged over years]. Salinity of the irrigation water did not affect yield of cured leaves in the SW2 - SW4 range. Nevertheless, in the same range quality of cured product was generally depressed due to increases in leaf Cl- and decreases of filling power (cm3 g-1) of cut tobacco. Overall, furrow irrigation significantly produced greater yield, mean cured leaves weight and IWUE as compared with drip irrigation (1.7 vs. 1.5 Mg ha-1, 5.8 vs. 5.2 g, 5.9 vs. 5.4 kg ha-1 mm-1). The drip-irrigation proved to be superior over conventional furrow irrigation for tobacco cultivation under open-field conditions.