Abstract

DIEZ, J.  and  ACRECHE, M.M.. Respuesta del tabaco al riego deficitario para dos fechas de trasplante. RIA. Rev. investig. agropecu. [online]. 2019, vol.45, n.1, pp.109-120. ISSN 1669-2314.

The production of tobacco Virginia in Argentina is located at Jujuy and Salta where crop irrigation is mainly done by a gravity system. The possibility of using precision irrigation methods and the low sensitivity of the crop to moderate water stress allow assuming that it is feasible to irrigate tobacco with a deficit strategy. The aim of this study was to evaluate the effects of high frequency deficit irrigation during the period that precede summer precipitation at the Valle de Lerma (Cerrillos, Salta) on tobacco leaf dry matter and its main component for two transplant dates. Attributes related to water and radiation use efficiencies were also determined. The study was conducted during three growing cycles (2013/14, 2015/16 y 2016/17) at INTA EEA-Salta with the tobacco Virginia variety K394. Treatments consisted of the combination of two transplant dates (early, Te; late, Ta) and two level of irrigation requirement (NR): 100 and 50% of NR. Leaf dry matter (MSh), total dry matter (leaf+stem), leaf area index (IAF) and specific foliar mass (MFE) were determined at different moments. Phyllochron, crop accumulated intercepted radiation (Rint) and radiation use efficiency (EUR) were determined in 2015/16 and 2016/17. Water use efficiency was calculated for the 20-24 leaf and harvest samplings considering the irrigation water (EUAr) and the water contributed by the rainfall and irrigation (EUApr). MSh at harvest was lower in 2013/14 than in the other growing cycles, but was similar for the two transplant dates in each growing cycle. Although Te received more incident radiation (300-400 MJ) than Ta, this only represented an extra 3% of Rint during the growing cycle. Therefore, the lowest MSh in 2013/14 was explained by the lowest IAF. IAF and MFE were similar between transplant dates in 2013/14 and 2016/17, whereas for the 2015/16 growing cycle the lower IAF at harvest found for Te generated leaves with higher MFE. There were not differences between transplant date for EUR at harvest, ranging from 0,46 to 0,48 g/MJ. Replacement of 50% of NR did not penalize MSh and IAF during the 2015/16 and 2016/17 growing cycles (when the fertilized used was liquid), whereas it decreased MSh and IAF in 2013/14 (when liquid fertilizer was used). EUApr was lower in 2013/14 than in the other growing cycles. EUApr was always higher for Ta than Te, and for 50% of NR only in 2015/16. During the three growing cycles the lowest EUAr was found with the combination of Ta and 50% of NR. The controlled deficit irrigation is an alternative for tobacco production in Valle de Lerma; however, studies considering leaf quality should be considering.

Keywords : dry matter; irrigation requirements; water use efficiency; radiation.