Influence of Harvest Intervals on Growth Responses and Fatty Acid Content of Purslane (Portulaca oleracea).

A greenhouse study was conducted to evaluate the influence of harvest intervals on biomass yield and omega fatty acids of 'Golden purslane' (Portulaca oleracea). Nutrients were supplied as a modified full-strength Hoagland solution two to three times weekly. Plants were harvested sequentially at 20, 40, and 60 days after transplanting (DAT) corresponding to 42, 63, and 84 days after sowing. Fatty acids were determined using a gas chromatography-mass spectrometry. Harvest intervals significantly influenced foliage fresh and dry weight, leaf number and plant height, and root length and fresh weight and were greatest at 60 DAT. Fatty acid analysis verified the presence of myristate, palmitate, linoleate, and linolenate at 20 DAT and in all three harvests, whereas stearate and oleate were detected only in the last two harvests (40 and 60 DAT). Linoleate, palminate, and linolenate were the most abundant fatty acids in purslane with levels in excess of 300 mg⋅kg-1. Those for myristate, stearate, and oleate were in excess of 200 mg⋅kg-1. The ratio of omega-6/omega-3 ranged from 0.44 for Harvest 1 to 1.1 for Harvest 3, whereas ratios for harvest intervals two and three were equal to or greater than the recommended daily human requirement. Results showed qualitative and quantitative differences of harvest intervals of purslane, suggesting that an optimal ratio of omega-6 to omega-3 fatty acids can be achieved ≈20 DAT. [ABSTRACT FROM AUTHOR]