Growth And Nutrition Laws Of Rainfed Potato Under Micro-ridge With Plastic Cover

Potato cultivation in dry land has an influential position in China. Thus, it has a crucial significance to improve the water and nutrient utilization rate of potato planting in dry land area. The most important requirement for yield increase in dry land potato production is trying to satisfy the water needed for potato growth as far as possible. By integrating the advanced experiences from both domestic and abroad, we put forward the micro-ridge covered with plastic film cultivation model for potato. In this model, the rainfall during potato growing period and the water in soil were utilized to the utmost extent by collecting rain water and maintaining the soil moisture. At the same time, nutrient disproportion is another key factor to restrain potato production. Therefore, we try to combine both the water saving cultivation during dry farming and the reasonable nutrient management to meet the water and nutrient requirement of potato growth, and achieve high-yield and high-efficiency in potato production. To realize this goal, we carried out the following study:1. Among several cultivation models such as micro-ridge with whole plastic-film mulching and furrow sowing, micro-ridge with plastic cover and furrow sowing, micro-ridge with whole plastic-film mulching and ridge sowing, high-ridge with plastic-film mulching and ridge sowing, flat cultivation with plastic-film mulching and flat cultivation only in dry land, potato production is significantly higher in two models of furrow sowing than in other models, indicating that furrow sowing and large scale plastic-film mulch had a better promotive effection on potato growing in dry land. The results showed that the optimal plating density of the No. 1 of KeXin cultivar in this model is about 52,500 plants /ha, named M3. Potato production reaches the highest yield in this optimal density for the selected cultivar.2. Under micro-ridge with whole plastic-film mulching and furrow sowing in dry land, growth of the root, stem and leaf showed the S curve. The maximum growth accumulation daily appears from July 20, to August 5. Precipitation at later stage of growth have a positive effect on production increase. Compared with the model without plastic-film mulching, dry mass accumulation in root, stem, leaf and tuber in early growth stage in micro-ridge with whole plastic-film mulching and furrow sowing model is key to gain high potato yield.3. Under micro-ridge with whole plastic-film mulching and furrow sowing in dry land model, the nitrogen, phosphorus and potassium content in potato leaf dropped with growth stage. The total accumulation of nitrogen, phosphorus and potassium in potato root, stem and leaves showed a unimodal curve, while the nitrogen, phosphorus and potassium in potato tuber increase with growth stage. Under this model, absorbtivity to nitrogen, phosphorus and potassium by potato varied at different growth stage: generally, potato use more nitrogen and potassium than phosphorus. It mainly absorbs nitrogen during early stage, and potassium utilization becomes priority after July 5.4. Compared with micro-ridge with whole plastic-film mulching and furrow sowing model, nitrogen utilization efficiency dropped in flat cultivation model which inorganic nitrogen content between 0-60 cm soils, is lower than that in micro-ridge with whole plastic-film mulching and furrow sowing model.With nitrogen application, inorganic nitrogen residue are higher in flat cultivation than in micro-ridge with whole plastic-film mulching and furrow sowing model. We found that in micro-ridge with whole plastic-film mulching and furrow sowing model, the utilization efficiency of nitrogen is improved, so that the yield is increased and the inorganic nitrogen residue is reduced. The apparent nitrogen loss is higher in micro-ridge with whole plastic-film mulching and furrow sowing model than in flat cultivation, indicating that it can be optimized further. For phosphorus and potassium, constant monitor should be taken as the management measure.5. Under micro-ridge with whole plastic-film mulching and furrow sowing in dry land model, the yield and starch content in tuber are obviously higher than that in control. The reducing sugar content appeared a trend of high in early stage but low in later stage, and decreased with growth stage. In the control, the reducing sugar content is always higher in the whole growth period, indicating a better effect of micro-ridge with whole plastic-film mulching and furrow sowing in dry land model in collecting rain water, increasing earth temperature, keep soil moisture and improving potato production and quality.6. Potato water utilization efficiency, water content in rhizosphere under micro-ridge with whole plastic-film mulching and furrow sowing in dry land model are significantly higher than flat cultivation, which as control test. Water content in soil varies with depth: obvious difference was observed among 0.40 -0.60m,0 -0.20m and 0.20 -0.40m. under the micro-ridge with whole plastic-film mulching and furrow sowing in dry land model, Water content in soil of 0-0.20m and 0.40-0.60m depth is significant different from the control.