| In recent years,with the continuous development of China’s social economy,a large number of labor force is rapidly transferred to the secondary and tertiary industries,and the area of direct seeding rice is expanding.However,the lack of understanding of the high yield and nutrient utilization characteristics of direct seeding rice,there are many problems in the production of direct seeding rice,such as less selection of high-yield varieties,extensive fertilizer input,poor production efficiency and safety,which seriously affects the high yield and good quality of direct seeding rice.In this study,9 late maturing mid japonica varieties and 6 early maturing late japonica varieties were used as materials in Jingjiang City,Jiangsu Province from 2018 to 2019.Three fertilization treatments,NPK,NK without P and PK without N,were designed by using dry direct seeding cultivation mode and referring to the amount of N,P and K applied in local high-yield cultivation.In order to provide technical support for the selection of rice varieties with high yield and high nitrogen and phosphorus efficiency in large-scale direct seeding cultivation,the yield,nitrogen and phosphorus absorption and utilization characteristics of different genotypes of rice varieties under direct seeding cultivation were studied.The main results are as follows:1.Under NPK treatment,Sujing 815 had the highest yield,followed by Nanjing 9108 and Nanjing 5055,which were significantly higher than Huaidao 5(control)and other varieties.Wuyunjing 31 was also 1.27%higher than Huaidao 5,but the difference was not significant.Under NK treatment,Sujing 815 had the highest yield,followed by Wuyunjing 31 and yangyujing 2.Under PK treatment,Nanjing 5055 had the highest yield,followed by Sujing 815 and Yangjing 805,and Huaidao 5.The yield of different rice varieties under the same fertilizer treatment was 2.0%higher than that of early maturing late japonica rice.The yield of different fertilizer treatments was NPK>NK>PK.The effect of nitrogen and phosphorus on rice yield was 21.67%and 7.38%,respectively.In terms of yield components,the average panicle number and grain number per panicle among different fertilizer treatments were NPK>NK>PK,and the panicle number was 5.98%and 19.29%higher,and the grain number per panicle was 8.69%and 6.83%higher.The average 1000-grain weight and seed setting rate were PK>NK>NPK,and the seed setting rate was 5.16%and 0.87%higher,and the 1000-grain weight was 7.78%and 2.50%higher.The yield components of different rice genotypes were also significantly different under the same fertilizer treatment.Under NPK treatment,the spikelet number per area of Sujing 815 and Nanjing 5055 was the highest,followed by Yangyujing 2 and Wuyunjing 23,which were significantly higher than other rice varieties,and the spikelet number was more than 320×104 hm-2.The highest number of grains per panicle was Zhendao 11,followed by Nanjing 9108,Sujing 815,Nanjing 5055 and Wuyunjing 31,and were significantly higher than other varieties,with more than 120 grains per panicle.The highest seed setting rate was Sujing 815,which had no difference with Nanjing 9108,but were significantly higher than other varieties,followed by Nanjing 5055,Yangjing 805,and the seed setting rate was about 90%.The largest 1000-grain weight is Huaixiangjing 15,followed by Nanjing 9108,Huaidao 5,Yangjing 805,1000-grain weight is generally more than 26 g.Large panicle,large panicle,high seed setting rate and high 1000-grain weight are the basic characteristics of high yield of direct seeding rice varieties.2.The peak seedling number,leaf area and dry matter accumulation of direct seeding cultivation population of different genotypes of rice varieties were NPK>NK>PK.Under NPK high-yield cultivation conditions,Huaidao 5 had the highest population peak seedling number,followed by Yangjing 805 and Yangyujing 2,which were significantly higher than other varieties.The highest LAI at tillering stage was Wuyunjing 23,followed by Sujing 815,Nanjing 5055,Yangjing 805,Huaixiangjing 15,Yangyujing 2 and Wuyunjing 31,and Wuyunjing 24.The highest LAI at heading stage was Nanjing 9108,Wuyunjing 23,followed by Sujing 815,Yangyujing 2 and Zhendao 11.The varieties with the highest dry matter accumulation were Sujing 815,followed by Nanjing 5055 and Nanjing 9108,which were significantly higher than those of other varieties,and the harvest index was also relatively high,mostly above 0.5.Dry matter accumulation of different rice varieties at mature stage showed that late maturing middle japonica was higher than early maturing late japonica,which was 1.29%higher.3.The nitrogen content and total nitrogen accumulation of different fertilizer treatments showed NPK>NK>PK at jointing stage,heading stage and mature stage,the phosphorus content of plant showed PK>NPK>NK,and the phosphorus absorption of plant showed NPK>NK>PK.The nitrogen and phosphorus content and accumulation of different genotypes of rice varieties also showed significant differences.Under NPK high-yield cultivation conditions,the plant nitrogen content was higher in Huaixiangjing 15,Zhendao 11,Yangyujing 2 and Wuyunjing 24 at jointing stage,and there was no significant difference among other varieties except Sujing 815,Nanjing 9108 and Huaidao 5 at heading stage.The nitrogen uptake of plants at the main growth stages was higher in Sujing 815,Nanjing 5055 and Nanjing 9108 than that of other rice varieties.The nitrogen uptake of Sujing 815 and Yangyujing 2 were significantly higher than other varieties before jointing stage,and Nanjing 5055 and Nanjing 9108 were also relatively high.The nitrogen uptake of Sujing 815,Nanjing 5055,Huaidao 5,Wuyunjing 31 and Yangjing 805 were the highest from jointing to heading stage.The nitrogen uptake of Sujing 815,Nanjing 9108,Yangjing 805,Huaidao 5,Wuyunjing 31,Yangyujing 2 and Wuyunjing 24 were the highest from heading to maturity stage.Sujing 815 had the highest phosphorus uptake in the main growth period,but it had no significant difference with Nanjing 5055 and Nanjing 9108 at jointing and heading stages.Sujing 815 had the highest phosphorus uptake before jointing and from jointing to heading,and was significantly higher than other varieties.Sujing 8 also had the highest phosphorus uptake from heading to maturity.4.Yangyujing 2 had the highest contribution rate of nitrogen among different genotypes,which was not significantly with Sujing 815 and Wuyunjing 24,but significantly higher than Huaidao 5(control)and other varieties,Huaixiangjing 15,Wuyunjing 31 and Nanjing 52 were also higher than Huaidao 5.The N agronomic use efficiency of Sujing 815 was the highest,followed by yangyujing 2,Wuyunjing 24 and Wuyunjing 31,which was significantly higher than that of Huaidao 5 and other varieties by 29.08%,and Nanjing 9108 was also 10.18%higher than that of Huaidao 5,but the difference was not significant.Yangyujing 2 had the highest N physiological use efficiency,which had no significant difference with huaixiangjing 15,Sujing 815 and Wuyunjing 24,but was significantly higher than Huaidao 5 and other varieties,17.62%～28.10%higher than Huaidao 5,and Wuyunjing 31 was also 4.76%higher than Huaidao 5.The N partial productivity of Sujing 815 was the highest,followed by Nanjing 9108,Nanjing 5055 and yangyujing 2,which were 7.37%～14.35%higher than Huaidao 5.The N uptake and utilization efficiency of Sujing 815 was the highest,followed by Yangyujing 2,which was significantly higher than Huaidao 5 and other varieties,and 19.11%～41.37%higher than Huaidao 5.In addition,Nanjing 5055,Nanjing 9108,Wuyunjing 31 and Wuyunjing 24 were higher than Huaidao 5 by 8.16%～13.01%,but the difference was not significant.The Nuptake and utilization efficiency of different varieties were higher in late maturing medium japonica rice than in early maturing late japonica rice.5.The highest phosphorus contribution rate of different genotypes was Nanjing 52(23.17%),followed by Nanjing 9108 and Nanjing 5055,which were significantly higher than Huaidao 5(control)and other varieties.The P agronomic use efficiency was the highest among Nanjing 9108,followed by Nanjing 52,Nanjing 5055,which were 1.51%significantly higher than Huaidao 5 and other varieties.Sujing 815 was also 13.15%higher than huairice 5,but the difference was not significant.The highest P physiological use efficiency was Zhenda 11,followed by Nanjing 5055,Nanjing 9108,Sujing 815,Wuyujing 24,Nanjing 52,Wuyujing 23 and yangyujing 2,which were 18.15%significantly higher than Huaidao 5(control)and other varieties.The highest P partial productivity is Sujing 815,followed by Nanjing 9108,Nanjing 5055 and yangyujing 2,which are 7.35%significantly higher than that of Huaidao 5 and other varieties.Nanjing 52 had the highest phosphorus uptake and utilization rate,followed by Nanjing 9108 and Nanjing 5055,which had no significant difference with Huaidao 5,but were higher than other varieties,and Nanjing 5055 and Wuyunjing 23 had no significant difference with Huaidao 5.The P uptake and utilization efficiency of different types of rice varieties were higher in late maturing medium japonica rice than in early maturing late japonica rice.Comprehensive analysis showed that late maturing medium japonica rice was suitable for high yield cultivation of direct seeding rice along the Yangtze River,followed by early maturing late japonica rice,Sujing 815 and Nanjing 5055 were suitable for high yield and nitrogen efficiency,and Nanjing 9108,Nanjing 5055 and Wuyunjing 23 were suitable for high yield and phosphorus efficiency. |
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