Uncovering seasonal "growth-nutrient-chemical components" coupling Alpinia galanga (L.) Willd.: A comparison between monoculture and intercropping agroforestry systems

Compared with monoculture (PA system), the growth status and yield of Alpinia galanga (L.) Willd. were better improved after intercropping with Camellia oleifera Abel (AC system), with higher land-use sustainability and ecological effects. To understand the seasonal relationships of growth, nutrient, chemical component changes between them, identify proper harvest time of A. galanga and provide proper cultivation methods for “ Camellia oleifera + Zingiberaceae species” intercropping system, growth and biomass status, N, P, K contents, soil physio-chemical properties and total flavonoid/phenol contents were analyzed in both PA and AC systems. The results indicated that A. galanga mostly had better growth, nutrient and medicinal quality conditions in AC system rather than PA system, and the best harvest time of rhizomes was autumn, balancing yield (6.10 kg/plant fresh weight) and medicinal quality (271.36 mg/kg total flavonoid and 106.34 mg/kg total phenol). Soil nutrient contents and the status of water holding capacity, porosity and soil aeration could also be improved in AC system. Moreover, A. galanga began to absorb nutrients from January to April, showing rapid growth status during July to October. Total nitrogen (TN) and flavonoid contents of A. galanga in AC system were positively correlated in each season, mantel test also showed that chemical component contents showed high correlations with ammonium nitrogen (AN) content in rhizosphere soil and total potassium (TK) content in rhizome, suggesting that N and K played dominant and significant assistant roles in flavonoid biosynthesis process. Fertilization should be carried out from April to October, and nutrient addition in autumn could release nutrient deficiency in A. galanga and C. oleifera , preparing better conditions in the following year. Appropriate intercropping of A. galanga and C. oleifera offered better strategies to improve soil characteristics, yield and land utilization rate in southern China and other similar countries. • Alpinia galanga showed “nutrient absorbing-rapid growth-redistribution” trend in AC system. • There were strong correlations between flavonoid, N and P contents in plant and soil. • Interspecies nutrient redistribution in AC system indirectly enhanced A. galanga performances. • P and K could be added at early growth stage, while N management should be thoroughly maintained.