Calcium nutrition influencing mineral content, nitrogen assimilation, flowering and yield of dragon fruit (Selenicereus monacanthus).

Abstract

Dragon fruit is considered as one of the important tropical fruit crops due to its nutritional significance. Under acidic soil condition, sustaining crop production is one of the major challenges. The present investigation aimed at assessing the efficacy of calcium nutrition on mineral composition, nitrogen assimilation, flowering and yield of dragon fruit under acidic soils of eastern tropical region. The treatments comprised of soil application of calcium @ 100, 200, 300, 400 and 600g hill-1 year-1. Calcium-absentia was considered as a control. Application of Ca @ 400g hill-1 year-1 exhibited the highest acquisition of minerals such as N, K, Ca, Zn, B and Cu in the matured old and recently matured shoots. Whereas P, Mg, Fe and Mn were largely attained with Ca @ 200 g hill-1 year-1. Maximal chlorophyll content, total carbohydrate, nitrate reductase activity, nitrogen use efficiency, highest fruit set percentage and overall fruit yield were also recorded with Ca @ 400 g hill-1 year-1. Significant correlation between the fruit yield and shoot calcium content, indicated the possible interplay of calcium in improving yield in dragon fruit through improved nitrogen assimilation and carbohydrate synthesis. The dose Ca @ 400 g hill-1 year-1 was conclusively considered as the optimal level of calcium nutrition for dragon fruit under acidic soils of eastern tropical regions. Furthermore, the level 600 g hill-1 year-1 did not result in significant appreciation of assessed variables and hence was adjudged as a supra-optimal dose.