Influences Of Phosphorus And Potassium On Ca,Mg And Mn Nutritional Characteristics And Nutrient Balance Of Winter Potato

The former studies on the effects of the application dosages of phosphate fertilizer and different potassium fertilizers in winter potato production mainly focused on the tuber yield and quality parameters,but there were few reports on the nutritional characteristics and relative nutrient balance of medium-elements and micro-elements in winter potato.The field experiments were carried out to probe into calcium,magnesium and manganese nutritional characteristics and the relative nutrient balance of winter potato with different phosphate fertilizer dosages and application of potassium fertilizers,which will provide a reference for rational application of fertilizers in potato cultivation in Guangdong Province.Four phosphate fertilizer levels were designed as follows:0（P0）、45.0（P1）、90.0（P2）、135.0（P3）kg·hm^-2,respectively;In addition,sulfate of potash and muriate of potash ratio experiments were set:total potassium（K₂O）amount for all the treatments was 312.0 kg·hm^-2,and the potassium type ratios were K₂SO₄:KCl=1:0,0:1and1:1,respectively.The main findings were as follows:（1）The absorption,accumulation and the proportion in the tubers of magnesium decreased with the increment of phosphate fertilizer application amount.It was also shown that the accumulation of Mg in whole plant increased at first and then decreased with growth stages in all treatments,and the rapid accumulation period was from 17 d to 45 d after the full-emergence stage with the accumulation peak appearing at 59 d;Besides,the accumulation of Mg in tubers showed a rising trend;The other results showed that the distribution proportions of Mg in leaves decreased gradually,but those in tubers behaved a rising tendency,so that the tubers became the pool of Mg at the mature stage.（2）The whole plant accumulation of Ca increased first and then decreased,which showed as follows:P2>P3>P1>P0 during the most growth periods;For all the treatments,the distribution proportions of Ca in each organ were as follows:leaf>stem>tuber during the whole growth period.In detail,the distribution ratio of Ca in the leaves behaved a decreasing trend,while the proportion of the distribution in the tubers increased throughout the whole growth stages.In addition,the distribution proportion of Ca in the tubers decreased with the increment of the amount of phosphate fertilizer.Therefore,properly supply of phosphorus fertilizer could increase the absorption and accumulation of Ca with the effect of P2 treatment(90 kg·hm^-2)being the best.（3）Properly supply of phosphorus fertilizer could increase the absorption and accumulation of Mn,the effect of P2 treatment(90 kg·hm^-2)was the best.The accumulation of Mn in whole plant increased with the growth period,and at 73 d after seedling emergence,P1,P2 and P3 treatment was significantly higher than that of P0treatment.During the whole growth period,the distribution of Mn mainly in leaves,less tubers.In this experiment under the condition,the plots of the application dosages of phosphate fertilizer need to absorbed CaO 0.59 kg,MgO 0.37 kg,Mn 0.016kg for per 1000kg yield.（4）The accumulation of Mg in the whole plant with different potassium fertilizers ratio was:K₂SO₄+KCl>KCl>K₂SO₄,and the K₂SO₄+KCl treatment with K₂SO₄ achieve significant differences（p<0.05）,besides,the K₂SO₄+KCl treatment has a higher Mg distribution ratio in the tubers,up to 58%.（5）The order of Ca content of stem-leaf、tuber and whole plant was:KCl>K₂SO₄+KCl>K₂SO₄,and KCl treatment is more conducive to the absorption of organs,and the average Ca accumulation of whole potatoes was showed:KCl>K₂SO₄+KCl>K₂SO₄,KCl treatment is more helpful for the accumulation of Ca in potato plants.（6）The order of the Mn content in the whole plant and the accumulation of Mn in the tuber was showed:KCl>K₂SO₄+KCl>K₂SO₄.And during the whole growth period,the K₂SO₄+KCl treatment distribution of Mn in the tubers was the highest,and the K₂SO₄+KCl treatment could promote the transport of Mn to the tubers.In this experiment under the condition,the uptake amount of CaO 0.53 kg,MgO 0.40kg,Mn 0.021 kg for per 1000 kg yield of different potash ratio treatment of plots.（7）By using M-DRIS diagnosis,it was shown that the smaller the the nutrient imbalance index of potato leaves was more favorable for the formation of yield.