Pathogenicity Analyses of Rice Blast Fungus (Pyricularia oryzae) from Japonica Rice Area of Northeast China.

In order to understand the pathogenicity differentiation of rice blast fungus (Pyricularia oryzae Cavara), a total of 206 isolates of P. oryzae were collected from three Japonica rice regions in Jilin Province, northeast China. Pathogenicity test showed that the reaction pattern of 25 monogenic differential varieties (MDVs) of rice (Oryza sativa L.) demonstrated a wide pathogenic diversity among the isolates. Those MDVs harbor 23 resistance (R) genes with the susceptible variety Lijiangxintuanheigu (LTH) as control. Virulent isolates of MDVs harboring R genes Pish, Pit, Pia, Pii, Pik-s, Pik, Pita (two lines), and Pita-2 (two lines) had high frequencies ranging from 80 to 100%, to MDVs harboring R genes Pib, Pi5(t), Pik-m, Pi1, Pik-h, Pik-p, Pi7(t), Piz, Piz-5, and Piz-t showed intermediate frequencies ranging from 40 to 80%, and to MDVs with R genes Pi3, Pi9(t), Pi12(t), Pi19(t) and Pi20(t) presented low frequencies ranging only from 0 to 40%. The U-i-k-z-ta pattern of race-named criteria categorized the 206 isolates into 175 races. Sub-unit U73 for Pib, i7 for Pi3 and Pi5(t), k177 for Pik-m/Pik-h/Pik-p, z17 for Pi9(t), and ta332 for Pi20(t) were crucial on pathogenic differences in regions. Twenty-seven standard differential blast isolates (SDBIs) were selected to characterize resistance in rice accessions. This study could help to build a durable identification system against blast in the Japonica rice area of northeast China and enhance our understanding of the differentiation and diversity of blast races in the world.

[Study on the Optimization Models of Nitrogen,Phosphorus and Potassium Application of Atractylodes japonica].

Objective: To optimize the nitrogen, phosphorus and potassium fertilization models of Atractylodes japonica to offer a scientific basis for its standard cultivation and the specialty fertilizers. Methods: Annual and biennial Atractylodes japonica were chosen in the experiment. By using three-factors, quadratic saturation-D optimal design, the effects of nitrogen, phosphorus and potassium on height, rhizome traits and active constituents of Atractylodes japonica were studied. Results: Considering the production and active constituents,the optimum plan of nitrogen, phosphorus and potassium fertilization model was selected as N0P2K2（ N 0 g/m2,P2O540. 227 g / m2,K2O 40. 227 g / m2） and N1P3K3（ N15. 939 g/m2,P2O567. 467 g / m2,K2O 67. 467 g / m2）. By means of regression equation with nitrogen, phosphorus and potassium ratio and production（ rhizome fresh weight） of Atractylodes japonica, potassium was the major factor in nitrogen, phosphorus and potassium single effect, and nitrogen came second. According to the regression model, the best combination of nitrogen, phosphorus and potassium was obtained. The highest fresh weight of Atractylodes japonica rhizome was 27. 4066 g when the fertilization level of nitrogen, phosphorus and potassium were 38. 4301 kg / hm2,181. 4750 kg/hm2,128. 5584 kg/hm2,respectively. The target fresh weight of Atractylodes japonica was selected as 26. 00 27. 41 g per plant according to the model optimization results, and the target production was 1 040. 0 1 096. 4 kg / hm2. In 95% confidence interval, the best fertilizer combinations were X1=-0. 2912± 0. 0825,X2= 0. 2764 ± 0. 1054 and X3= 0. 1325 ± 0. 0645. Conclusion: According to the yield and active constituents of Atractylodes japonica, which suggest that the fertilizing amount of Atractylodes japonica artificial planting is nitrogen 46. 951 59. 320 kg / hm2,phosphorus 131. 673 155. 377 kg / hm2 and potassium 120. 091 134. 597 kg / hm2.