Screening Of Nitrogen-efficient Genotypes Of Red Beet Varieties And Study On Differences In Phenotypic Characteristics

Beet belongs to Amaranthaceae,which is an important economic crop.Red beet is a kind of vegetable which is very popular and widely used.Nitrogen plays an important role in the growth process of red sugar beet.The unreasonable use of nitrogen will lead to waste of resources,pollution of soil and living environment,increase of cost and so on.Through screening nitrogen efficient materials,we can understand the phenotypic characteristics of nitrogen efficient material,which can provide reference value for the promotion and cultivation in the future.In this paper,10 different red beet varieties were screened.In the artificial climate culture room,low nitrogen treatment(hydroponic culture 1.5 mmol·L^-1,soil culture N50mg·kg^-1)and normal nitrogen treatment(hydroponic culture 5 mmol·L^-1,soil culture N120 mg·kg^-1)were set.Eight nitrogen efficiency screening indexes were determined by means of Hydroponic culture primary screening and soil culture secondary screening.Finally,nitrogen dry matter production efficiency was used as the screening index of nitrogen efficient red beet varieties,Then the red beet varieties with different nitrogen efficiency were verified by field experiment.According to the screening results,the varieties with high nitrogen efficiency and low nitrogen efficiency were studied from the aspects of morphological characteristics,physiological characteristics,root configuration and biological yield.The main results are as follows:(1)The difference of dry weight in different nitrogen efficiency red beet varieties.The aboveground dry weight and underground dry weight of nitrogen efficient'Yegina S2'were significantly higher than that of nitrogen inefficient'CYCLHDAR'under low nitrogen treatment.(2)Differences in leaf morphology.Under low nitrogen treatment,there was no significant difference in leaf length and leaf width between the two varieties,but there were significant differences in petiole length.Under the condition of normal nitrogen,there was no significant difference in leaf morphology between the two cultivars.(3)Differences in root architecture.Root configuration of'Yegina S2'was significantly higher than that of'CYCLHDAR'under low nitrogen conditions.Under normal nitrogen treatment,there was no significant level between two varieties.(4)Difference in photosynthetic parameters.Pn,SPAD and chlorophyll a values of'Yegina S2'were significantly higher than'CYCLHDAR'in low nitrogen treatment.Pn,Ci and Tr nitrogen efficient varieties were significantly higher than those with low nitrogen efficiency.(5)The NR and GDH activities of low nitrogen treatment'Yegina S2'were significantly higher than those of'CYCLHDAR',and the GS activities of'Yegina S2"in normal nitrogen treatment was significantly higher.Under different nitrogen treatments,the yield of nitrogen efficient'Yegina S2'variety was significantly higher than that of nitrogen inefficient'CYCLHDAR'variety.