‘Doce do Havaí’ Maize Cultivar Presents Tolerance to Saline Stress in Hydroponic Cultivation

Abstract

This study evaluated the effects of salinity on the development, growth and biomass production of two sweet maize genotypes ("Tropical Plus®" and "Doce do Havaí") and compared the oxidative stress marker responses of plant tissues from roots and leaves of different seedlings submitted to different amounts of NaCl in a nutrient solution. The experiment was carried out in a complete random design, in a 2x4 factorial arrangement (two sweet maize genotypes and four salt concentrations: 0, 50, 100 and 150 mM NaCl). Previously, the seeds were distributed in Styrofoam trays containing commercial substrate and, 10 days after sowing, the seedlings were transferred to 2-litter plastic pots, containing nutrient solution without NaCl addition, where they were kept for 8 days. NaCl was added to the nutrient solution, according to the treatments. Each treatment consisted of four pots containing six plants each. The plants were kept in B.O.D. at 25°C with 18/6 light for 14 days. The nutrient solution with NaCl addition was changed every 7 days until the end of the experiment. Saline stress reduced root (13% and 29% for Hawaiian and "Tropical Plus®", respectively) and shoot length (36% for "Doce do Havaí" and 48% for "Tropical Plus®"), fresh shoot (29% for "Doce do Havaí" genotype, and 70% for "Tropical Plus®") and root mass (18% and 38% for "Doce do Havaí" and "Tropical Plus®", respectively), shoot diameter (18% and 20% for "Doce do Havaí" and "Tropical Plus®", respectively) and chlorophyll content in both genotypes, with results more significative in "Tropical Plus®" hybrid seedlings. However, the concentrations of proline and malondialdehyde in roots and leaves, as well as conductivity, increased in response to the addition of NaCl, mainly in "Doce do Havaí". These results suggest that the "Doce do Havaí" genotype is more tolerant to salinity compared to "Tropical Plus®" hybrid, and may be indicated for breeding programs aiming to develop saline tolerant plants.