| At present,the phenomenon of excessive application of chemical fertilizers is common in apple production.Excessive application of chemical fertilizers not only endangers the ecological environment such as soil,but also affects the quality and yield of apples.Therefore,the research on the technology of chemical fertilizer reduction and synergism and the explore of the mechanism are of great importance for promoting the sustainable development of apple industry and improving quality and efficiency of apple production.In this study,hydroponic culture and soil culture were chosen.Malus hupehensis Rehd.var.pinyiensis Jiang was used as materials to study the changes of growth,nutrient uptake capacity and nutrient accumulation of apple seedlings under different nutrient conditions together with‘BIHU’.The aim was to explore the effects of‘BIHU’on the growth and nutrient absorption of apple seedlings under the conditions of chemical fertilizer reduction.It would provide some theoretical basis for the reduction of chemical fertilizer application in apple production.The results of the study were as follows:1.Under the conditions of reduced nutrients,although the growth of apple seedlings was affected,the overall changes were not significant.Within a certain range,the increase in nutrient supply did not necessarily promote the growth of apple seedlings.Under normal and medium nutrient conditions,there were no significant differences in the chlorophyll content of apple seedlings.But in those apple seedlings under the lower nutrient conditions,the content of chlorophyll decreased significantly.It indicated that slight reduction in nutrients did not affect the chlorophyll content of the plants.Low nutrients had a certain impact on apple’s leaves and roots,manifested as decreased soluble protein content and root vigor.After the nutrient reduction,the root structure of apple seedlings changed.Under medium nutrient conditions,the root structure index decreased,while in the low nutrient conditions,although the total length of the root tip,the total surface area,the total number of root tips and the number of lateral roots increased,but the average root diameter and total volume decreased significantly.However,applying’BIHU’could relief the adverse effects of reduced nutrient supply on the growth and nutrient accumulation of apple seedlings to a certain degree,and even promote the seedlings to present the same performance as those seedlings under normal nutrient conditions.It showed that’BIHU’could promote the growth of apple seedlings under low nutrient conditions.2.Low nitrogen,low phosphorus and low potassium had different influences on apple seedlings.After applying’BIHU’,the effects of low nutrient stress on the growth of apple seedlings were alleviated,and the absorption and utilization of nutrients were promoted.The application of’BIHU’significantly increased the activities of nitrate reductase(NR)and glutamine synthetase(GS)in roots of apple seedlings,significantly increased the nitrogen utilization,and promoted nitrogen accumulation in roots,stems and leaves.What’s more,the application of‘BIHU’enhanced the activity of Na~+/K~+-ATPase in leaves and roots of apple seedlings,and increased the accumulation of potassium.The effects of‘BIHU’on apple seedlings under low phosphorus stress were not significant,but it also alleviated to some extent.All the results showed that’BIHU’could promote the nutrient absorption and utilization efficiency of apple seedlings to a certain extent. |
