Germination of Indian Almond (Terminalia arjuna Roxb.) Seeds as Affected by Soil Salinity in Presence or Absence of Magnetic Iron

Abstract

The hard seed coat is the major hindrance in achieving good and uniform germination for Indian almond (Terminalia arjuna Roxb.) fruits, especially when large plantations are to be raised under soil salinity stress. The present investigation was therefore, undertaken under the full sun at the nursery of Orman Botanical Garden, Giza during 2016 and 2017 seasons with the objective to find out the role of magnetic iron (Fe3O4) on mitigating the hazards of NaCl salinity, when applied at the rates of 0 or 3 g/20-cm-dimater plastic pot containing 10 fruits of arjuna and filled with about 3.5 kg of sand + clay mixture at equal parts (1:1, v/v) salinized with NaCl pure salt at the concentrations of 0, 2000, 4000, 6000 and 8000 ppm. The effect of interactions between Fe3O4 application rates and salinity levels was also studied in a complete randomized design experiment with factorial concept replicated thrice. The obtained results indicated that means of germination percentage were descendingly decreased with increasing salinity level to reach less than 50 % by 6000 and 8000 ppm levels, while planting the fruits in a soil mixture free from salt gave the highest germination %, followed by planting in 2000 ppm-salinized soil mixture, and then planting in soil mixture salinized with 4000 ppm concentration. On the other hand, addition of Fe3O4 (3 g/pot) significantly raised the mean of this measurement in both seasons. The shortest period to either maximum germination (G.V.) or 50 % germination (MGR) was achieved in both seasons by planting in non salinized control and 2000 ppm-salinized media, whereas increasing salinity level over that (up to 8000 ppm) prolonged these periods with the greatest delay in germination. On the contrary, Fe3O4 significantly reduced the means of such two traits causing a marked accelerating in G.V. and MGR. A slight increment was noticed in the means of germination rate index (GRI) by the different salinity concentrations, while Fe3O4 caused a trivial decrement. A similar response occurred as well regarding the means of vigour index (V.I.), seed viability (S.V.), hypocotyl length and vegetative and root growth attributes of the resulted seedlings. So, it can be advised to apply magnetic iron (Fe3O4) at the rate of 3 g/pot (20-cm-diameter) to improve germination and seedling quality of Terminalia arjuna Roxb. fruits planted in either low or medium salinized soil.