Growth and nutrient efficiency of the main yam varieties in central Hebei plain

Objectives Genotypes, ecological conditions and cultivation techniques resulted in great differences in the growth and nutrient use efficiencies of yams from different habitats. The growth characteristics and nutrient requirement of three main cultivated yam varieties were compared, aiming to provide a support for high-efficient nutrient management in sustainable production of yam.

Methods The main yam varieties were Bangyao, Xiaobaizui and Ziyao in the central Hebei plain. The yam samples were respectively collected at 80 d, 110 d, 140 d and 180 d after sowing in the conventional field. Dry and fresh biomass were weighed, and the N, P and K contents in yam tubers, stems and leaves were determined.

Results The biomass of stems and leaves increased firstly and then decreased with yam growing, while the maximum biomass of tuber appeared at the harvest. The tuber fresh biomass of Bangyao was significantly higher than those of Ziyao and Xiaobaizui, but the tuber dry matter of Bangyao was not higher because of its lower planting density. Compared with Ziyao and Xiaobaizui, the maximal accumulation speed of fresh and dry biomass of Bangyao were not higher, but the fleet accumulation durations of fresh and dry biomass of Bangyao were both longer, and the time reached the maximal accumulation rate was later. In addition, the significant differences in accumulation, distribution and use efficiency of nutrients were found among the three yam varieties. The rank of accumulation nutrients was all showed in the order of K₂O > N > P₂O₅ and tubers > leaves > stems in the tested three yam varieties. Bangyao had the highest accumulations of N, P₂O₅ and K₂O, and highest production efficiency of nutrients, but no significant difference was found between Ziyao and Xiaobaizui. Bangyao had the longest fleet accumulation duration and the highest maximal accumulation speed of N and K₂O, while the characteristics of accumulation dynamics of P₂O₅ had no significant differences among three varieties.

Conclusions The characteristics of growth and nutrient accumulation had no significant differences between Ziyao and Xiaobaizui, but the biomass, yield and production efficiency of nutrients of Bangyao were significantly higher than those of Ziyao and Xiaobaizui, and the nutrient demand for forming unit yield was significantly lower than those of Ziyao and Xiaobaizui.