Study On The Optimal Nutrients Management And Regulatory Mechanism Of Root Vegetables

Hebei province is one of the main provinces for the production of vegetables as well as root vegetables. But the unscientific fertilization in production has become a serious impediment to the healthy development of root vegetables. This study was conducted in Shangyi county of Zhangjiakou city and Qingyuan county of Baoding city, the main production regions of radish and carrot in Hebei province. Through field experiments, this paper systematically analyzed the characteristics of growth and nutrient accumulation of root vegetables, and its regulatory mechanism under different nutrient levels. The objective was to provide a theoretical basis and technical support for rational fertilization and the healthy development of root vegetables in Hebei province. The main results were as follows:1. According to the yields and nutrients accumulation rates of radish and carrot under different nutrient levels, and the comprehensive analysis of soil fertility, the optimum nutrient rates of radish and carrot were N 150~180 kg N /hm2 and 165~195 kg N /hm2, P2O5 60~80 kg /hm2 and 75~105 kg /hm2, K2 O both 105~135 kg /hm2, respectively.2. The amount of dry matter accumulated by whole plant and fleshy root increased with the plant growth, while that by leaf firstly increased and then decreased during the growing period, and its peak was observed in fleshy root development stage. With the increase of fertilizer application rate, the total amount of dry matter accumulation also increased firstly and then decreased.3. The N, P2O5 and K2 O accumulations of radish and carrot also increased firstly and then decreased with the increase of fertilizer application rates. But there were no obvious effects of different fertilizer levels on nutrients accumulation rate producing per unit yield of radish and carrot. For producing 1000 kg yield, radish required N1.06~1.55 kg, P2O5 0.69~1.06 kg and K2 O 1.02~1.46 kg, and carrot demanded N1.64~1.99 kg, P2O50.90~1.19 kg and K2O1.30~1.94 kg, respectively. The proportion of N, P2O5 and K2 O was 1:0.60~0.71:0.89~1.07 and 1:0.54~0.61:0.79~1.03, separately. The results also indicated that RE, AE and PFP all significantly decreased with the increasing of N, P2O5 and K2 O inputs. PFPP and PFPK under different N levels, PFPN and PFPK under different P2O5 levels, PFPN and PFPP under different K2 O levels all increased and then decreased accompanying with the increased fertilizer application rates.4. The regulatory mechanism of suitable fertilizer promoting the growth and development of root vegetables was further analyzed. The results indicated that compared to the control, suitable fertilization significantly increased the dry matter accumulation duration and maximum accumulation rate of radish by 2.0~8.4d and 16.5%~36.3%, respectively. And it also increased N, P2O5, K2 O accumulation duration by1.5~6.5d, 1.3~5.4d and 4.1~11.7d, separately, increased N, P2O5, K2 O maximum accumulation rate by 9.2%~39.4%, 11.0%~30.2% and 8.3%~51.0%, respectively. Carrot also showed the same trends. Suitable fertilization significantly increased the dry mattera ccumulation duration and maximum accumulation rate of carrot by 3.2~13.9d and 5.6%~73.0%, respectively. And it also increased N, P2O5, K2 O accumulation duration by 4.3~13.9d, 3.1~9.5d and 1.9~15.1d, separately, increased N, P2O5, K2 O maximum accumulation rate by 11.4%~34.5%, 2.1%~20.0% and 8.7%~33.3%, respectively.