Impact of pH on the growth and nutritional profile of Lemna minor L. as a sustainable alternative for Pakistan’s feed sector

Pakistan’s conventional feed supply is rapidly depleting, forcing the country to turn to non-conventional sustainable feed to meet the demand of the livestock and fishery sectors. The current study investigates the effect of pH on the nutritional composition of Lemna minor L., a freshwater macrophyte and a potential alternative feed. Fronds were grown in a pH range of 4–10 and replicated three times. The growth rate was highest (90 g m −2 day −1 ) at pH 7 while lowest (40 g m −2 day −1 ) at pH 4. Protein content dropped sharply at pH 4, but the highest (31 g/100 g) was found at pH 7 and 8. The lipid fraction was high at greater pH values (9, 10), while low in acidic conditions. Carbohydrate was maximum (59.3 g/100 g dw). A higher level of Ca (34, 37, 38 mg/100 g dw) was observed in pH 5 and 6 while low Ca content (24 mg/100 g dw) was recorded for the control group. In contrast, the Mg level slightly increased with increasing pH while the maximum concentration (32 mg/100 g dw) was observed at pH 10 and in the control group. High Fe moiety (936 mg/100 g) was found at pH 5 and 6. Higher Mn (3.0 mg/100 g) was seen at a slightly acidic pH. The lowest level of Mn (1.7 mg/100 and 2.0 mg/100) was recorded at pH 9 and 10, respectively. The highest fraction of Zn (0.08 mg/100 g) was observed in pH 6 and 7 while the lowest Zn came at pH 9. The study concluded that L. minor grows best between pH 6 and 10 under the current agroclimatic conditions of Pakistan with an optimal nutritional profile.