Effects Of Phosphate And Potash Fertilizer's Application Amount And Nitrogen Application Methods On Potato Growth And Root Physiology

The experiments were carried out from 2016 to 2017 at Tiaoshan experimental station?37°11'N,104°03'E?,Baiyin,Gansu province,to evaluate the growth and development indexes as well as root physiology and root morphological characteristics of Potato?Solanum tuberosum L.cv.Cultivar Atlantic?under different levels of K and P fertilizer applications under drought stress and various ratio of N basal fertilizer and topdressing fertilizer under normal irrigation.The main conclusions of our experiments were as follows:The experiments were conducted in a plastic greenhouse and potato materials were subjected to six K levels:0?1.2?2.4?3.6?4.8?6.0g?per plant?and six P levels 0?0.485?0.97?1.455?1.94?2.425 g?per plant?under three water conditions:normal irrigation?taken as contrast?,mild drought and moderate drought respectively.Responses concerned potato root resistant physiology,morphological characteristics and plant biomass accumulation along with tuber yield were illustrated and the results indicated that,potato growth and dry matter accumulation above ground were inhibited to some extent with the water deficit,while applications with proper dosage of P,K fertilizer could improve the root water content and root vigor,alleviate the imbalances of free radical generating and scavenging by enhancing the activities of SOD,POD and CAT,reduce the producing rate of O₂^·-as well as MDA content.Attenuate the inhibition on the potato growth and development caused by drought,enhance the overall drought resistance of plants,thus,the potato tuber weight was significantly increased.Drought stress affected the distribution of dry matter in potato over and under ground,resulted in the increase of biomass of underground parts.Meanwhile the root to shoot ratio enhanced.The application of K and P fertilizer could also improve the dry weight of underground parts,however,there were no significant differences in root to shoot ratio under different K fertilizer levels and different P levels.In the aspect of potato root morphological development,the total root length,root volume,root surface area and root diameter increased under K treatments,on the whole.But the high K application amount showed a negative effect on the total root length and number of root tips under moderate drought.P fertilizer could increase the total root length,root volume,root surface area and root diameter of potato as well within limits,nevertheless,a high P dosage showed a negative effect on the root diameter under normal irrigation and number of root tips under drought stress.Deserve to be mentioned,compared to K fertilizer,the effect of P on root elongation was more significant.There showed a significant positive correlation between P application amount and total root length under moderate drought.Comparing the six P and K application levels with contrast,it was the best to promote the potato drought resistance and growing development with 202.5 kg K?K₂O?fertilizer and153 kg P?P₂O₅?fertilizer per hectare.In addition,This study evaluated the agronomic trait and root physiological status of potato cultivar Atlantic grown under normal irrigation conditions among 7 N fertilizer treatments including two control groups:N-deficient?no nitrogen applied?and conventional field N treatment along with five different ratio:1:0?0:1?1:5.7?1:1.2?1:0.54N basal fertilizer and topdressing.It turned out that,Neither single N basal fertilization or full amount apply during growth period would not be beneficial to the improvement in root physiological activity and formation of tuber yield.In the study of effects concerning different N fertilizer application models,65%N using as basal fertilizer and 35%using as topdressing fertilizer was most favorable for the establishment of potato root system.In addition to guaranteeing a coordinating and balanced development between overground segment and underground segment,a higher tuber weight and harvest indexes could be obtained at the same time.