Basic Characteristics Of Rapeseed Varieties (Brassica Napus L.) With Different Types Of Phosphorus Use Efficiency For Grain Production

Field experiments were carried out to study basic characteristics of rapeseed varieties (Brassica napus L.) with different types of phosphorus use efficiency for grain production(PUEg).73conventional rapeseed varieties were cultured in2006-2007(2007treatment), and98conventional rapeseed varieties were cultured in2007-2008at the low nitrogen fertilization level (0kg ha-1)and high nitrogen fertilization level (180kg N ha-1). At beginning flowering stage,dry matter weight (DMW)and the phosphorus content of different organs (leave and stem) were tested, and at maturing stage agronomic characteristics, DMW and the phosphorus content of different organs (stem, shell and seed) were tested. The tested rapeseed varieties were classified into5types (A, B,C, D, E) based on PUEg by the MinSSw method, agronomic characteristics and phosphorus accumulation and distribution of different types were studied. According to2008N0and2008N1treatments, the tested rapeseed varieties were classified into3types (low type, middle type and high type) based on PUEg under different nitrogen fertilizer levels, then these varieties were divided into eight types (Lâ†'L, Lâ†'M, Lâ†'H, Mâ†'L, Mâ†'M, Mâ†'H,Hâ†'M, Hâ†'H) baded on change of different types from low nitrogen fertilizer to high nitrogen fertilizer, responses of PUEg on nitrogen fertilizer were studied. The heterosis performance, general combining ability(GCA), specific combining ability(SCA) and genetic effect of PUEg in rapeseed were investigated in22parents (the numbers of female and male parents were17and5, respectively) and their17×5=85F1hybrids. The purposes of these studies were to investigate the basic characteristics of rapeseed with higher PUEg and to provide fundamental information in rapeseed breeding and feasible cultivation measures designment. Results were as following:1. There are three indexes of phosphorus use efficiency, including phosphorus use efficiency for grain production (PUEg). phosphorus use efficiency for plant biomass (PUEp) and phosphorus harvest index (PHI). Yield is the most important factor during rapeseed production. There were significantly positive correlations between PUEg and yield (r2007=0.3167**,r2008=0.3663**. r2009=0.4784**). The study of path analysis indicated that the indirect influence of PUEg on yield was biggest. So PUEg was a more suitable index to indicate nitrogen efficiency than PUEp and PHI.2. PUEg differed greatly among rapeseed varieties used in this study. Range of PUEg was from69.43g/g to137.23g/gin2007treatment, from66.62g/g to89.79g/g in2008N0treatment, from53.38g/g to79.58g/g in2008N1treatment, and increasing ratio (the most value to the minimum value) was97.66%,34.79%and49.08%, respectively. Range of PUEg in hybrid combination was from40.88g/g to142.09g/g in2009N0treatment, from56.56g/g to98.53g/g in2009CK treatment, from56.78g/g to125.39g/g in2009P0treatment, and increasing ratio (the most value to the minimum value) was247.56%,74.18%and120.84%, respectively. There were four varieties in A types in different treatments, and they were Ningyou7, N06-5,4029and YC7。There were three varieties in D or E types in different treatments, and they were Ningyou18. Xiang05483and YN02。3. Sink capacity (total number of seeds) increased with increasing of PUEg in different type varieties, and there were significantly positive correlations between PUEg and total number of seeds (r2007=0.4418**, r2008N0=0.2666**, r2008N1=0.4355**). There were significantly positive correlations between PUEg and number of primaryBranches(r2007=0.2687**,r2008N0=O.2335**, r2008N1=0.3291**), and there were significantly positive correlations between PUEg and number of pods (r2007=0.3167**, r2008N0=0.2968**, r2008N1=0.3843**). There were significantly positive correlations between number of primary branches and number of pods (r2007=0.8007**,r2008N0=0.7424**, r2008N1=0.3680**). Number of pods with high number of primary branches were high, and sink capacity were also high. So number of pods and primary branches could be screening indexes of variety with high PUEg.4. There were significantly positive correlations between PUEg and yield (r2007=0.3167**, r2008N0=0.3663**, r2008N1=0.4784**), and there were significantly positive correlations between PUEg and the ratio of DMW of seed to biomass (r2007=r2007=0.5703**,r2**8NO=0.5354**r2008N1=0.5033**). The relationship between PUEg and phosphorus accumulation at flowering stage were not significant(r2008N0=-0.0077, r2008N1=0.0469), and there were significantly negative correlations between PUEg and phosphorus accumulation at maturing stage (r2007=-0.7019**. r2008N0=-0.3195**, r2008N1=-0.4911**). There were significantly negative correlations between PUEg and phosphorus accumulation after flowering (r2008NO=-0.2486*, r2008N1=-0.4192**), and with increasing of PUEg at different types phosphorus accumulation after flowering decreased.5. There were significantly negative correlations between PUEg and content of protein (r2008N0=-0.3746**. r2008N1=-0.2672**,r2009N0=-0.4493**. r2009CK=-0.3736**, r2009p0=-0.4115**), and there were significantly positive correlations between PUEg and content of fat (r2008N0=0.4105**, r2008N1=0.3670**,r2009N0=O.2955**,r2009CK=0.3652**, r2009**P0=0.4928). In conventional rapeseed treatments there were significantly positive correlations between PUEg and fat accumulation (r2008N0=0.4884**,r2008N1=0.5432**), and with increasing of PUEg at different types fat accumulation increased.6. Responses of PUEg on nitrogen fertilizer were studied and results showed that number of varieties at same types (L-L. M-M. H-H) under two nitrogen fertilizer levels was51. and the ratio of51to98(total number) was52.04%. Three were13varieties in M-L and G-M. and the ratio was13.27%. Three were34varieties in L-M, L-G and M-G, and the ratio was34.69%. In L-M, L-G and M-G, added values of the number of seeds per pod and yield were larger, and added values of phosphorus accumulation of whole plant and different organs, ratios of phosphorus accumulation of stem and shell to total phosphorus accumulation were smaller. Decreasing values of ratio of phosphorus of seed to total phosphorus accumulation were smaller. The trends of the varieties in M-L and G-M by nitrogen application (Mâ†'L, Hâ†'M) were opposite.7. The heterosis and genetic effect of PUEg in rapeseed was investigated in22parents (the numbers of female and male parents were17and5, respectively) and their17×5=85F1hybrids. Results showed that number of positive Hm was larger than that of negative Hm, and number of positive Hh was larger than that of negative HI, so positive heterosis of PUEg existed. Differences of genetic parameters of NUEg were bigger. Additive effects and dominance effects were all significant in low nitrogen fertilizer(2009N0). In2009CK and2009P0treatments GCA were less and SCA were bigger, and dominance effects dominance effects were more important.