Variability in permeability and integrity of cell membrane and depletion of food reserves in neem (Azadirachta indica) seeds from trees of different age classes

Abstract

We quantified cell membrane permeability (electrical conductivity-EC, water soluble sugar-WSS, and amino acids-AA) and integrity (phospholipids, α-tocopherol and lipid peroxidation) along with food reserve deterioration (total proteins, total sugar, and total starch) of neem seeds collected from various mother tree age classes and stored for 65 days in airtight plastic containers at ambient room temperature (35±5°C). Results show that the activities were higher in fresh seeds (EC 267.56–2950.01 μS/g, WSS 19.96–19.48 mg/g and AA 5.40–5.35 mg/g) and declined with increasing duration of storage period (EC 153.37–195.17 μS/g, WSS 3.13–4.17 mg/g and AA 4.29–4.49 mg/g after 35 days and EC 144.02–161.56 μS/g, WSS 2.06–2.40 mg/g and AA 3.98–4.27 mg/g after 65 days of storage). Phospholipids and α-tocopherol were higher in fresh seed (0.073–0.093 OD at 710 nm and 0.080–0.105 OD, respectively) and declined as storage duration increased (0.033–0.042 OD at 710 nm and 00.0010–0.0020 OD, respectively). Dead seeds showed reduced amounts of phospholipids and minimum activity of α-tocopherol (antioxidants). The level of MDA was lower in fresh seeds (0.0066–0.0087 OD at 600–535 nm) and increased as storage duration increased (0.0248–0.0268 OD after 65 days of storage). The higher amount of MDA indicated that seeds died due to rancidity of the oil inside the seed. Neem seed cake was assessed for deterioration of food reserves (total proteins, total sugar, and total starch), concentrations of which were higher in fresh seed and declined as storage duration increased. Germination was higher in fresh seeds and after 65 days, no germination was received perhaps due to deterioration of biochemicals in seeds. Patterns of seed deterioration were similar across all seed lots.