Effects of different planting density, leaf position and leaf age on growth and quality of Artemisia argyi var. argyi 'Qiai'

Abstract

In order to guide the standardized planting and scientific harvesting of Artemisia argyi var. argyi 'Qiai', effects of diffe-rent planting density, leaf position and leaf age on the growth and quality of A. argyi var. argyi 'Qiai' were studied in this paper. The results showed that appropriate sparse planting could increase stem diameter, compact leaf spacing, increase the leaf size, reduce the rate of withered leaves and increase the number of effective leaves. Dense planting can significantly increase the yield of A. argyi var. argyi 'Qiai' per Mu(1 Mu≈667 m~2) and the output rate of moxa, but reduce the yield per plant and the number of effective leaves. With the decrease of leaf position and the increase of leaf age, the leaf size and the weight of one hundred leaves increased at first and then decreased, the density of non-glandular hair field of the lower epidermis and the output rate of moxa decreased. With the increase of planting density, the contents of eucalyptus oleoresin, camphor, α-platyclone, and cyanidin decreased gradually, the contents of chlorogenic acid, isochlorogenic acid B, isochlorogenic acid A and isochlorogenic acid C in the leaves of A. argyi var. argyi 'Qiai' increased gradually, while the contents of borneol, bornyl acetate and isozelanin increased at first and then decreased significantly. With the decrease of leaf position and the increase of leaf age, the contents of volatile oil, phenolic acid and flavonoid in A. argyi var. argyi 'Qiai' decreased gradually. PCA analysis can divide the leaf quality characteristics of A. argyi var. argyi 'Qiai' into two parts: the middle and upper 10-30 days leaf age, the middle and lower 40-50 days above leaf age. Based on the above factors, the planting density of 28 000 plants/Mu(row spacing of 10 cm×20 cm) can be selected for cultivation of A. argyi var. argyi 'Qiai' rhizome, and the effective plants in the field are about 142 800 plants/Mu. In terms of harvesting, it is suggested that the A. argyi var. argyi 'Qiai' should be harvested on "March 3 rd" and "May 5 th" of the lunar calendar. If it is the traditionally harvested at one time in May, the A. argyi var. argyi 'Qiai' should be divided into two parts: the middle and upper leaves, the middle and lower leaves, so as to achieve high quality and high price of A. argyi var. argyi 'Qiai' leaves and improve the economic benefits of A. argyi var. argyi 'Qiai' planting.