Growth and yield responses of two ginger species to different levels of nitrogen

Abstract

Nitrogen (N) is a critical determinant of plant growth and productivity, but there is limited information on the agronomic parameters of medicinal plants. Three levels of N fertiliser (0, 1.375 and 1.625 g plant−1) were used to investigate the effects of fertilisation on the growth and yield parameters of two ginger species (Siphonochilus aethiopicus and Zingiber officinale). The experiment was conducted in the glasshouse with six treatments (two ginger species and three levels of N fertiliser) arranged in a randomised complete block design and replicated four times. The results indicated that N application significantly affected plant height, leaf number, chlorophyll content and rhizome yield of the species for two cropping seasons. Scanning electron microscopy analyses of stomata opening revealed that a higher N level increased the number of open stomata in both ginger species. The results showed that with application of 1.625 g N plant−1 both ginger growth and yield were higher compared with the lowest N fertiliser application levels. However, the growth parameters of Z. officinale were variably greater than those of S. aethiopicus. Therefore, the present study demonstrates that application of 1.625 g N plant−1 to commercial ginger and African ginger can be used to improve growth and yield.