Growth, chlorophyll content, and visual symptoms of noni (Morinda citrifolia L.) seedlings affected by macronutrient deficiency

Morinda citrifolia L. is a plant utilized for its food and medicinal benefits. However, a lack of information on its nutrient requirement limits the yield potential of this crop for commercial cultivation. Therefore, the response of noni seedlings to the application of complete nutrient solution with or without omission of one macronutrient (to determine the most limiting one) was studied. The treatments consisted of 7 nutrient solutions (Complete Nutrient Solution (CNS) and CNS minus (-) each of N, P, K, Mg, Ca, and S) and four application volumes (0 ml (control), 100 ml, 200 ml, and 300 ml NS) arranged in a randomized complete block design with four replicates in a greenhouse. Data on stem height, stem diameter, number of leaves, leaf area, and visual nutrient deficiency symptoms were assessed at four weeks intervals, starting from the 4th week after transplanting (WAT) in sand culture. Total dry matter yields and leaf chlorophyll content were determined at 20 WAT. The seedlings treated with CNS presented the highest growth in terms of all the variables, with no deficiency symptoms, whereas seedlings treated with CNS-N had the least growth, chlorotic leaves, and a stunted appearance throughout the period of the study. Overall, the order of growth limitation in seedlings was as follows: -N˃-Ca˃-Mg˃-P˃-K˃-S˃CNS. The seedlings treated with 100 ml NS had the best performance as compared to the control and other treatments. These results indicated that N followed by Ca and Mg are the most limiting macronutrients for noni seedling development and are required in relatively small quantities.