Effect of leaf maleic hydrazide concentration on yield and dry matter partitioning in burley tobacco (Nicotiana tabacum L.)

Abstract

Abstract Maleic hydrazide (MH) is commonly used to prevent axillary bud (sucker) development in tobacco (Nicotiana tabacum L.) after inflorescences have been removed by topping. Although MH provides an inexpensive and effective method to control sucker development, high concentrations (> 80 μg g−1) of MH ratidue in cured leaves are undesirable. The objective of this study was to determine the effect of a wide range of MH rates on leaf MH residue, yield, and dry matter partitioning among plant parts of burley tobacco. The feasibility of using near infrared spectroscopy as a method to rapidly screen tobacco samples for MH residue also was tested. MH was applied at rates of 0 (suckers manually removed), 1.68, 3.36, 5.04, 6.72, 10.08, and 13.44 kg ha−1, where 3.36 kg ha−1 corresponds to the usual commercial rate. Adequate sucker control was provided for up to 3 weeks by 1.68 kg ha−1 MH. Concentrations in the leaves (midribs removed) increased progressively with increasing rate of MH. Concentration of MH decreased over time but plants treated with rates above 3.36 kg ha−1 had MH concentrations at or above 80 μg g−1 in air-cured leaves of the upper third of the canopy. Leaf MH concentration decreased from the top to the bottom of the plant, and at MH rate above 6.72 kg ha−1, the MH concetration was above 80 μg g−1 in leaves at the bottom of the canopy. Air-cured leaf yield was slightly increased for the 1.68 kg ha−1 MH rate compared with hand-suckered controls, but higher MH rates did not further affect yield. A large portion of the yield increased cured-leaf moisture content of MH-treated plants. Additionally, MH-treatment decreased partitioning of dry matter in stalks. On a whole-plant basis, dry matter accumulation was similar for all treatments. The results indicated that MH rates above 3.36 kg ha−1 did not alter plant development, yield, or sucker control, but did lead to excessive undersirable leaf MH concentrations. For cured-leaf and especially midrib tissue, there was a significant relationship between MH concentrations determined by the chemical method and estimated by NIR spectroscopy. These results indicated that the potential exists to use NIR spectroscopy to rapidly estimate MH residue levels of tobacco leaf tissue.