Chitosan is a promising natural biopolymer that stimulates growth, increases yield, and boosts-up plants' immune systems. A field experiment was conducted to study the effect of foliar application of chitosan on growth, yield and quality attributes (viz. chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoids, total ash and major nutrient contents) of red amaranth. The field experiment was laid out in a Randomized Completely Block Design (RCBD) with three replications and six treatments [viz. T0 = Control (no chitosan application); T1 = 100 mg L-1; T2 = 150 mg L-1; T3 = 200 mg L-1; T4 = 250 mg L-1 and T5 = 300 mg L-1 chitosan solution]. The study results revealed that the application of chitosan at different doses had no significant effect on plant height, the number of leaves plant-1, and the moisture content of red amaranth. But there were significant variations in stem diameter, root length, and yield of red amaranth. Similarly, the application of chitosan at different doses also showed a significant effect on chlorophyll contents, carotenoids and total ash contents of red amaranth. The average chlorophyll-a, chlorophyll-b, total chlorophylls, carotenoids and ash content of red amaranth ranged from 6.02-9.51, 3.67-5.92 and 9.68-15.15 mg g-1 tissue, 0.20-0.28 µg g-1 sample (fresh wt.), and 16.36-17.69%, respectively. Among the major nutrient elements, the amount of Ca, Mg, Na, K and P in red amaranth was statistically insignificant among the treatments. On the contrary, the effect of foliar application of chitosan at different doses disclosed a statistically significant difference in S, Zn and Fe contents of red amaranth. The highest amounts of chlorophyll-a, carotenoids, total ash, S, and Fe in red amaranth were obtained from treatment T5. Finally, the study results concluded that foliar application of chitosan at 300 mg L-1 has a significant positive effect on the growth, yield, pigments, S, and Fe contents of red amaranth.

The study was carried out to evaluate the effects of various doses of foliar application of chitosan on spinach growth, yield, and quality characteristics (including chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoids, total ash, and main nutrient contents). The Randomized Completely Block Design (RCBD) was used to set up the field experiment, with six treatment combinations [T0 = Control (no chitosan application), T1 = 100 ppm chitosan solution, T2 = 150 ppm chitosan solution, T3 = 200 ppm chitosan solution, T4 = 250 ppm chitosan solution, and T5 = 300 ppm chitosan solution] and three replications. The results revealed that applying chitosan at different doses significantly affected growth (viz., plant height, the number of leaves per plant) and yield of spinach. Moreover, due to the application of chitosan at various doses, there were notable differences observed in chlorophyll, total phenol, and ash contents of spinach. The spinach sample contained an average of 13.61–15.82 mg per g of chlorophyll–a, 9.16–10.18 mg per g of chlorophyll–b, and 22.77–25.85 mg per g of total chlorophyll. On the contrary, the effect of foliar application of chitosan at different doses showed a statistically significant difference in the P, K, Zn, and Fe contents of spinach. The highest amounts of chlorophyll-a, total ash, P, and K in spinach were obtained from treatment T3. However, the results showed that most of the biochemical properties of spinach were reduced by the higher doses (treatments T4 and T5) of foliar application of chitosan. Finally, according to the study's findings, foliar application of chitosan at the rate of 200 ppm significantly affects the growth, yield, pigments, total ash, P, and K contents of spinach.