Effects Of Different Factors On The Yield And Photosynthesis Characteristic Of Kohlrabi In The Middle Of The Loess Plateau Region

Shortage of rainfall and fertilizer is main factor that restricts the improvement of dry land productivity for a long time in northern China.A research about high-yield culture technique of the kohlrabi was conducted in Yangou watershed.The effects of different water and fertilizer levels,mulching treatment,different stages of supplemental fertilizer,and the different level of concentration in PPU on economic yield were completed.The results showed as follow:1.supplementary irrigation during the expanding tuber period and combining with fertilize can improve major economic properties and increase the photosynthetic capacity. The economic coefficient of kohlrabi increased obviously with increasing of supplementary irrigation quantities.In the year that the rainfall is 290.1mm during growth period,the irrigation treatments of no irrigation,being irrigated with 10mm,the highest yields of kohlrabi was being combined with fertilizer treatment of N225kg/hm2 and P20573.33kg/hm2 separately. the yield of kohlrabi was the highest treatment and is 39360.00kg/hm2 with 20mm irrigation and N315kg/hm2 and P20573.33kg/hm2.At the dfferent level of water and fertilizer,the curve of photosynthetic diurnal variation of kohlrabi had one peak,that diurnal change of transpiration rate was double peak curve.The main correlation coefficients were Ca,RH,PAR.2.Effects of the plastic film mulching can maintain water,the yield of tuber was increased by 43.6 percent than the treatment of open ground.3.The economic yield and WUE were enhanced significantly after supplemented nitro-gen fertilizer dressing in different growth stages.The resume growth period was the best of supplemental nitrogen fertilizer dressing,the yield of tuber was 34133.33㎏/hm2.In different growth stages the curve of photosynthetic diurnal variation of kohlrabi had one peak, and the diurnal change of transpiration rate was double peak curve,the main correlation coefficients are PAR,Ca,RH.4.Spraying the PPU can improve the yield of kohlrabi,the highest yield was 40053.3㎏/hm2 at the level of 0.05 percent, having an obvious midday depression of photosynthetic rate at the level of 0.1 percent.