Moringa leaves contain a proper amount of antioxidants, amino acids, vitamins, hormones,
macronutrients, and micronutrients. Therefore, it is applied as a natural, inexpensive,
and simple-to-make biostimulant to boost nutritional value and growth parameters in
a variety of plants. The main purpose of this study is to determine the optimal concentration
of Moringa oleifera L. leaf extract (MLE) as an effective biostimulant to improve
nutritional and physical quality in cabbage (Brassica oleracea var. capitata). To
do this, three concentrations of MLE (6, 8, and 10%) were foliar sprayed to the plant
leaves at a rate of 25 mL plant−1 for every two weeks from transplantation till harvest,
while control plants (Ø) were sprayed with distilled water only. Our results show
that MLE greatly increased cabbage growth, nutrient content, pigment content, and
nutrient absorption, while a high concentration of 10% MLE could also significantly
reduce nitrate content in cabbage leaves. In comparison to the control plants, sprays
of 6%, 8%, and 10% MLE reduced nitrate content by 23%, 14%, and 12%, respectively.
However, the lowest nitrate content was found for the plants sprayed with 6% MLE.
Except for the dry matter, all the growth parameters, mineral content, and pigment
content were significantly higher after spraying with 10% MLE, while better vitamin
C and lower nitrate were found in the plants treated with 6% MLE. A Pearson correlation
reveals that head weight has a positive correlation with head diameter, head height,
chlorophyll a, and carotenoids at p levels of 0.01 and a positive correlation with
chlorophyll b and vitamin C at p levels of 0.05. Vitamin C and dry matter, on the
other hand, had a negative connection with nitrate content.
