论文部分内容阅读
Shurong XIN1，2， Xiuying YU3， Zhengtao YANG1，2， Shichun JIAN4， Dongfeng ZHENG1，2， Wenfan BIAN1，2， Hongtao SHAN1，2， Chang??ai ZHANG5
1.Agricultural Resources and Environment Institute of Shandong Agriculture Science Academy， Jinan 250100， China； 2. Key Laboratory of Wastes Matrix Utilization， Ministry of Agriculture， Jinan 250100， China； 3. Jiyang County Agricultural Bureau， Jinan 251400， China； 4. Shouguang Academy of Agricultural Mechanization Sciences， Jinan， 250100， China； 5. Zhejiang University of Science and Technology， Hangzhou 310023， China
Abstract The effects of soil moisture content， pot seedling buried depth， and pot seedling height on the survival rate and growth of dry planted seedlings were researched by field experiment. The results showed that the seedling survival rate and growth were enhanced with the increase of soil moisture content after pot seedling transplanting， but there was no significant difference in the survival rate and growth of seedlings with 85% and 100% of soil moisture content. Pot seedling buried depth was one of the important factors affecting the survival rate， and when the pot seedlings were buried 2 cm deep， the seedlings showed high survival rate and excellent growth. Under the same condition of soil moisture content and buried depth， seedlings with pot seedling height of 15 cm had the best survival rate and growth. Therefore， the optimized conditions for dry??cultivated rice seedling planting were soil moisture content of 85%， pot seedling buried depth of 2 cm， and pot seedling height of 15 cm.
Key words Dry??cultivated rice seedling planting； Soil moisture content； Pot seedling buried depth； Pot seedling height； Seedlings survival rate； Seedling growth
The Yellow River tidal flats and coastal saline soils in Shandong Province have become arable dry soils with the decline of groundwater level， and they can obtain high economic income by planting rice[1-2]. Through direct seeding， dry??cultivated rice has been planted in a certain scale in the area. However， direct??seeded rice in saline??alkali soil is prone to have problems such as delayed emergence of seedlings and salt damage of young seedlings. If the pot seedling transplanting method is adopted， these risks can be avoided， and the whole growth period of rice can be increased through the increase of the growth period in the nursery stage， thereby obtaining higher yield[3-4].
Dry??cultivated rice seedling planting is a rice planting method that is directly transplanted or dry??cultivated on the basis of dry land preparation. This method has the advantages of shortening rice growth cycle， saving irrigation water， reducing fertilizer loss and waste， improving and maintaining soil physical and chemical properties， and facilitating farming in the dryland soils of northern China[5-6]. According to existing studies， transplanting conditions such as the ages of dry??cultivated seedlings and the buried depth of seedlings have certain effects on rice yield[7-8]. However， in general， there are few reports on the dry??cultivated rice seedlings， so it is necessary to conduct in??depth research. In this study， the effects of soil moisture content， pot seedling buried depth， and pot seedling height on the survival rate and growth of dry planted seedlings were researched through the exploration of the optimized soil and seedling conditions for pot rice transplanting， so as to provide technical basis for the promotion of dry??cultivated rice seedling planting technology and the development of machinery. Materials and Methods
Test materials
The test rice variety was a new japonica rice variety "A7927" which was suitable for dry cultivation bred by the Institute of Crops of the Chinese Academy of Agricultural Sciences. The test was conducted in 2016 in the paddy field of Jiyang County， Shandong Province. The test seedlings were cultivated by our research group. The nursery seedling plates were 60.5 cm ?? 33.5 cm in size with 561 holes per plate， and 3 seeds were put in each pot. Test soil was the mixture of the sedimentary tidal fluvo??aquic soil of the Yellow River， which accounted for 85% of the total mass， with fermented slag and turfy soil according to 1?? 1. The specific physical and chemical properties of the tested sandy fluvo??aquic soil are shown in Table 1.
Test methods
The tests had 3 groups of treatments with different soil moisture content， pot seedling buried depths， and pot seedling heights. The pot seedlings were sown on April 15th， and the bred seedlings were then transplanted to a plot for cultivation. The plot was 5 m long and 4 m wide. By artificial transplanting， the plant spacing of the pot seedlings was 17 cm ?? 20 cm. Each hole was transplanted with 1 seedling， and there were a total of basic seedlings of 300 000/hm2. At 24 h after transplanting， watering was performed through furrow irrigation.
Soil moisture content test There were 5 treatments with soil moisture content of 55%， 65%， 75%， 85%， 100%， respectively， noted as T1， T2， T3， T4， T5， respectively. Repeat. On May 10， seedlings of 2??leaf age were selected for transplanting. At this time， the moisture content in the pot seedling medium was about 60%， and the field investigation was conducted on June 3. The seedlings of each group were buried consistent in depth of 2 cm.
Pot seedling buried depth test The effect of pot seedling buried depth on the survival rate of seedlings was studied under the soil moisture content of 85%， and there were a total of 4 buried depths， namely， 0， 1， 2， 3 cm， respectively， which were noted as A1， A2， A3， and A4， respectively. Other test conditions were the same as those in Soil moisture content test.
Pot seedling height test The effect of pot seedling height on the survival rate of seedlings was studied under the condition of 85% of soil moisture content and 2 cm of buried depth. Different plant heights were achieved by selecting seedlings of different leaf ages. In this test， 4 groups of seedlings with different leaf ages of 2， 3， 4 and 5 were selected， which were noted as B1， B2， B3， and B4， respectively （Table 2）. Other test conditions are were the same as those in Soil moisture content test. Data Analysis
The data was processed by SAS system， and the significant analysis was performed by Duncan??s new multiple range method. Excel 2003 was used for the drawing.
Results and Analysis
Effects of soil moisture content on survival rate and growth of pot seedlings
As shown in Fig. 1， the survival rates of different treatments from high to low were in the order of T5>T4>T3>T2>T1. Among the 5 treatments， there was no big difference in the survival rates of pot seedlings between saturated soil moisture content （100%） and soil moisture content of 5%， both of which showed significant differences from the other treatments. Moreover， the survival rate of treatment T4 was 30.8%， 19.7% and 10.0% higher than that of treatments T1， T2， T3， respectively， and the differences reached the extremely significant level. Since the temperature was high when transplanting the pot seedlings （27-29 ??）， the seedlings were immediately watered and irrigated after transplanting. The survival rates of transplanted pot seedlings of treatments T1， T2 and T3 which had small moisture content were only about 70%， and the survival rate of transplanting under the condition of 85% of soil moisture content reached as high as 90%. Therefore， the soil moisture content is crucial to the success of pot seedling transplanting.
As shown in Table 3， the growth of pot seedlings showed the same trend as the survival rates， and the performances of seedling quality indicators from high to low were all in the order of T5>T4>T3>T2>T1. Compared with treatments T1， T2 and T3， treatment T4 had the stem diameter increased by 66.7%， 40.0%， and 12.9%， respectively， plant height increased by 34.8%， 24.5% and 13.4%， respectively， and 100??plant overground dry weight increased by 53.3%， 43.3%， and 27.8%， respectively. However， there was no significant difference in each indicator between treatments T4 and T5. Considering factors such as saving water resources， facilitating mechanical walking， and suiting dry planting， 85% of soil moisture content is an ideal condition for dry??cultivated pot rice seedling planting.
Effect of pot seedling buried depth on the survival rate and growth of seedlings
As shown in Fig. 2， under the conditions of buried depths， the survival rates of seedlings from high to low were in the order of A3>A2>A4>A1. Compared with other treatments， treatment A3 had the survival rate increased by 12.6%， 4.3%， and 6.1%， respectively. The survival rate of treatment A3 was significantly higher than that of treatment A1. As shown in Table 4， the performances of seedling quality indicators from high to low were all in the order of A3>A4>A2>A1. Compared with treatments A1， A2 and A4， treatment A3 had the stem diameter increased by 84.2%， 40.0%， and 20.7%， respectively， plant height increased by 54.8%， 21.1%， and 11.9%， respectively， and 100??plant overground dry weight increased by 53.3%， 27.8， and 12.2， respectively. Therefore， the enhancing effect of treatment A3 was significant in stem diameter， plant height and 100??plant overground dry weight. Considering the survival rate and seedling quality， the optimized buried depth is 2 cm.
Effect of pot seedling height on survival rate and growth of seedlings
As shown in Fig. 3， the survival rates of seedlings with different pot seedling height from high to low were in the order of B3>B2>B4>B1， and the survival rate of treatment B3 was 10.7%， 4.8%， 5.9% higher than that of the other 3 treatments. Moreover， treatment B3 showed significant differences from treatment B1， while the difference was not significant between treatments B2 and B4.
As shown in Table 5， the performances of seedling quality indicators from high to low were all in the order of B3>B4>B2>B1. Compared the various indicators of each group before transplanting with those after transplanting， the growth of seedlings was enhanced with the increase of pot seedling height when the transplanting was done to the seedlings of less than 15 cm high， while the growth was slowed down when the pot seedlings was over 15 cm high， and the growth was the best at the transplanting seedling height of 15 cm. Therefore， the optimized transplanting plant height was 15 cm.
Discussion and conclusion
Soil salinization is very obvious in the Yellow River tidal flats and coastal areas. With the decline of groundwater level， these areas have gradually become arable dry land， and some successful experiences have been gained in planting rice on these soils[9]. Rice is a high??yield and high??efficiency crop in Shandong Province. The development of rice production is of great significance to ensure the sustainable development of agriculture[1]. However， the implementation of rice direct seeding on saline??alkali soil is prone to have problems such as late emergence of seedlings， uneven emergence of seedlings， and salt damage of seedlings. These risks can be avoided using dry??cultivated pot seedlings.
Rice seedlings are generally divided into pot seedlings and blanket seedlings[11]. With the standardized cultivation methods being recognized， pot seedlings have been valued because of the advantages of rapid seedling recovery， uniform seedling growth and effective yield improvement[12]. In the practice of dry??cultivated rice planting， the transplanting of pot seedlings can bring in complete roots and more seedling substrates， which is the preferred scheme for mechanized planting. In this study， the effects of soil moisture content， pot seedling buried depth and pot seedling height on the transplanting of seedlings are studied. The results show that the survival rate and growth of seedlings increase with the increase of soil moisture content， but the change is not significant when the soil moisture content is over 85%. When the pot seedling buried depth is smaller than 2 cm， the survival rate and growth of seedlings increase with the increase of buried depth， both of which achieve the best effects at the buried depth of 2 cm， while the indicators decrease when the buried depth is deeper than 2 cm. The survival rate and growth of seedlings are the best at the pot seedling height of 14 cm， and the survival rate and growth are affected if the pot seedlings are too high or too short. Therefore， the optimized conditions for dry??cultivated rice seedling planting are soil moisture content of 85%， pot seedling buried depth of 2 cm， and pot seedling height of 15 cm.
References
[1] WU X， YANG LQ， CHEN F， et al. Current status and development countermeasures of rice production in Shandong Province[J]. Shandong Agricultural Sciences， 2013， 45（5）： 119-125.
[2] SHEN CJ， HAN XH， YU L. The situation and development trend of rice cultivation mechanization technology at home and abroad[J]. Journal of Agricultural Mechanization Research， 2010（12）： 240-243.
[3] CHENG WD， ZHANG GP， ZHAO GP， et al. Differences in accumulation and translocation of the nutrients and dry matter between dry and paddy cultures of rice cultivar Jiazao 935[J]. Acta Agronomica Sinica， 2003， 29（3）： 413-418.
[4] CHENG JP， LUO XW， FAN QZ， et al. Influence of different planting methods on growth and development characteristics and yield of rice[J]. Journal of Huazhong Agricultural University （Natural Science Edition）， 2010， 29（1）： 1-5.
[5] DENG ZM， ZHAN BQ. Effects of different seedling ages on yield traits of hybrid late rice[J]. Fujian Science and Technology of Rice and Wheat， 2000（3）： 15-17.
[6] WANG JX， WANG DL， CHEN LH. Experimental study of yield response to maturity and transplanting time of rice seedling[J]. Irrigation and Drainage， 2000， 19（2）： 29-31.
[7] FANG SJ. Experimental study on relationship between dry age and yield[J]. China Agricultural Information， 2017（8）： 61-63.
[8] XIE SH， LI HM， LUO HL. Studies of seedling??raising methods on the growth and yield composition of late hybrid rice[J]. Crop Research， 2003（2）： 78-80.
[9] ZHANG YP， DU RC， DIAO PS， et al. Experiment of non??tillage and drought direct sowing rice and feasibility analysis in Shandong Province[J]. Transactions of the Chinese Society of Agricultural Engineering， 2016， 32（12）： 24-30.
[10] XIN MJ， REN WT， SONG YQ， et al. Effects of rice direct seeding on growth and yield[J]. Journal of Shenyang Agricultural University， 2014， 45（2）： 175-179.
[11] CHENG JP， WU JP， LUO XW， et al. Influence of different planting methods on growth characteristics and yield of early rice[J]. Hubei Agricultural Sciences， 2011， 50（3）： 457-460.
[12] ZHANG HC， ZHU CC， HUO ZY， et al. Advantages of yield formation and main characteristics of physiological and ecological in rice with nutrition bowl mechanical transplanting[J]. Transactions of the Chinese Society of Agricultural Engineering， 2013， 29（21）： 50-59.
1.Agricultural Resources and Environment Institute of Shandong Agriculture Science Academy， Jinan 250100， China； 2. Key Laboratory of Wastes Matrix Utilization， Ministry of Agriculture， Jinan 250100， China； 3. Jiyang County Agricultural Bureau， Jinan 251400， China； 4. Shouguang Academy of Agricultural Mechanization Sciences， Jinan， 250100， China； 5. Zhejiang University of Science and Technology， Hangzhou 310023， China
Abstract The effects of soil moisture content， pot seedling buried depth， and pot seedling height on the survival rate and growth of dry planted seedlings were researched by field experiment. The results showed that the seedling survival rate and growth were enhanced with the increase of soil moisture content after pot seedling transplanting， but there was no significant difference in the survival rate and growth of seedlings with 85% and 100% of soil moisture content. Pot seedling buried depth was one of the important factors affecting the survival rate， and when the pot seedlings were buried 2 cm deep， the seedlings showed high survival rate and excellent growth. Under the same condition of soil moisture content and buried depth， seedlings with pot seedling height of 15 cm had the best survival rate and growth. Therefore， the optimized conditions for dry??cultivated rice seedling planting were soil moisture content of 85%， pot seedling buried depth of 2 cm， and pot seedling height of 15 cm.
Key words Dry??cultivated rice seedling planting； Soil moisture content； Pot seedling buried depth； Pot seedling height； Seedlings survival rate； Seedling growth
The Yellow River tidal flats and coastal saline soils in Shandong Province have become arable dry soils with the decline of groundwater level， and they can obtain high economic income by planting rice[1-2]. Through direct seeding， dry??cultivated rice has been planted in a certain scale in the area. However， direct??seeded rice in saline??alkali soil is prone to have problems such as delayed emergence of seedlings and salt damage of young seedlings. If the pot seedling transplanting method is adopted， these risks can be avoided， and the whole growth period of rice can be increased through the increase of the growth period in the nursery stage， thereby obtaining higher yield[3-4].
Dry??cultivated rice seedling planting is a rice planting method that is directly transplanted or dry??cultivated on the basis of dry land preparation. This method has the advantages of shortening rice growth cycle， saving irrigation water， reducing fertilizer loss and waste， improving and maintaining soil physical and chemical properties， and facilitating farming in the dryland soils of northern China[5-6]. According to existing studies， transplanting conditions such as the ages of dry??cultivated seedlings and the buried depth of seedlings have certain effects on rice yield[7-8]. However， in general， there are few reports on the dry??cultivated rice seedlings， so it is necessary to conduct in??depth research. In this study， the effects of soil moisture content， pot seedling buried depth， and pot seedling height on the survival rate and growth of dry planted seedlings were researched through the exploration of the optimized soil and seedling conditions for pot rice transplanting， so as to provide technical basis for the promotion of dry??cultivated rice seedling planting technology and the development of machinery. Materials and Methods
Test materials
The test rice variety was a new japonica rice variety "A7927" which was suitable for dry cultivation bred by the Institute of Crops of the Chinese Academy of Agricultural Sciences. The test was conducted in 2016 in the paddy field of Jiyang County， Shandong Province. The test seedlings were cultivated by our research group. The nursery seedling plates were 60.5 cm ?? 33.5 cm in size with 561 holes per plate， and 3 seeds were put in each pot. Test soil was the mixture of the sedimentary tidal fluvo??aquic soil of the Yellow River， which accounted for 85% of the total mass， with fermented slag and turfy soil according to 1?? 1. The specific physical and chemical properties of the tested sandy fluvo??aquic soil are shown in Table 1.
Test methods
The tests had 3 groups of treatments with different soil moisture content， pot seedling buried depths， and pot seedling heights. The pot seedlings were sown on April 15th， and the bred seedlings were then transplanted to a plot for cultivation. The plot was 5 m long and 4 m wide. By artificial transplanting， the plant spacing of the pot seedlings was 17 cm ?? 20 cm. Each hole was transplanted with 1 seedling， and there were a total of basic seedlings of 300 000/hm2. At 24 h after transplanting， watering was performed through furrow irrigation.
Soil moisture content test There were 5 treatments with soil moisture content of 55%， 65%， 75%， 85%， 100%， respectively， noted as T1， T2， T3， T4， T5， respectively. Repeat. On May 10， seedlings of 2??leaf age were selected for transplanting. At this time， the moisture content in the pot seedling medium was about 60%， and the field investigation was conducted on June 3. The seedlings of each group were buried consistent in depth of 2 cm.
Pot seedling buried depth test The effect of pot seedling buried depth on the survival rate of seedlings was studied under the soil moisture content of 85%， and there were a total of 4 buried depths， namely， 0， 1， 2， 3 cm， respectively， which were noted as A1， A2， A3， and A4， respectively. Other test conditions were the same as those in Soil moisture content test.
Pot seedling height test The effect of pot seedling height on the survival rate of seedlings was studied under the condition of 85% of soil moisture content and 2 cm of buried depth. Different plant heights were achieved by selecting seedlings of different leaf ages. In this test， 4 groups of seedlings with different leaf ages of 2， 3， 4 and 5 were selected， which were noted as B1， B2， B3， and B4， respectively （Table 2）. Other test conditions are were the same as those in Soil moisture content test. Data Analysis
The data was processed by SAS system， and the significant analysis was performed by Duncan??s new multiple range method. Excel 2003 was used for the drawing.
Results and Analysis
Effects of soil moisture content on survival rate and growth of pot seedlings
As shown in Fig. 1， the survival rates of different treatments from high to low were in the order of T5>T4>T3>T2>T1. Among the 5 treatments， there was no big difference in the survival rates of pot seedlings between saturated soil moisture content （100%） and soil moisture content of 5%， both of which showed significant differences from the other treatments. Moreover， the survival rate of treatment T4 was 30.8%， 19.7% and 10.0% higher than that of treatments T1， T2， T3， respectively， and the differences reached the extremely significant level. Since the temperature was high when transplanting the pot seedlings （27-29 ??）， the seedlings were immediately watered and irrigated after transplanting. The survival rates of transplanted pot seedlings of treatments T1， T2 and T3 which had small moisture content were only about 70%， and the survival rate of transplanting under the condition of 85% of soil moisture content reached as high as 90%. Therefore， the soil moisture content is crucial to the success of pot seedling transplanting.
As shown in Table 3， the growth of pot seedlings showed the same trend as the survival rates， and the performances of seedling quality indicators from high to low were all in the order of T5>T4>T3>T2>T1. Compared with treatments T1， T2 and T3， treatment T4 had the stem diameter increased by 66.7%， 40.0%， and 12.9%， respectively， plant height increased by 34.8%， 24.5% and 13.4%， respectively， and 100??plant overground dry weight increased by 53.3%， 43.3%， and 27.8%， respectively. However， there was no significant difference in each indicator between treatments T4 and T5. Considering factors such as saving water resources， facilitating mechanical walking， and suiting dry planting， 85% of soil moisture content is an ideal condition for dry??cultivated pot rice seedling planting.
Effect of pot seedling buried depth on the survival rate and growth of seedlings
As shown in Fig. 2， under the conditions of buried depths， the survival rates of seedlings from high to low were in the order of A3>A2>A4>A1. Compared with other treatments， treatment A3 had the survival rate increased by 12.6%， 4.3%， and 6.1%， respectively. The survival rate of treatment A3 was significantly higher than that of treatment A1. As shown in Table 4， the performances of seedling quality indicators from high to low were all in the order of A3>A4>A2>A1. Compared with treatments A1， A2 and A4， treatment A3 had the stem diameter increased by 84.2%， 40.0%， and 20.7%， respectively， plant height increased by 54.8%， 21.1%， and 11.9%， respectively， and 100??plant overground dry weight increased by 53.3%， 27.8， and 12.2， respectively. Therefore， the enhancing effect of treatment A3 was significant in stem diameter， plant height and 100??plant overground dry weight. Considering the survival rate and seedling quality， the optimized buried depth is 2 cm.
Effect of pot seedling height on survival rate and growth of seedlings
As shown in Fig. 3， the survival rates of seedlings with different pot seedling height from high to low were in the order of B3>B2>B4>B1， and the survival rate of treatment B3 was 10.7%， 4.8%， 5.9% higher than that of the other 3 treatments. Moreover， treatment B3 showed significant differences from treatment B1， while the difference was not significant between treatments B2 and B4.
As shown in Table 5， the performances of seedling quality indicators from high to low were all in the order of B3>B4>B2>B1. Compared the various indicators of each group before transplanting with those after transplanting， the growth of seedlings was enhanced with the increase of pot seedling height when the transplanting was done to the seedlings of less than 15 cm high， while the growth was slowed down when the pot seedlings was over 15 cm high， and the growth was the best at the transplanting seedling height of 15 cm. Therefore， the optimized transplanting plant height was 15 cm.
Discussion and conclusion
Soil salinization is very obvious in the Yellow River tidal flats and coastal areas. With the decline of groundwater level， these areas have gradually become arable dry land， and some successful experiences have been gained in planting rice on these soils[9]. Rice is a high??yield and high??efficiency crop in Shandong Province. The development of rice production is of great significance to ensure the sustainable development of agriculture[1]. However， the implementation of rice direct seeding on saline??alkali soil is prone to have problems such as late emergence of seedlings， uneven emergence of seedlings， and salt damage of seedlings. These risks can be avoided using dry??cultivated pot seedlings.
Rice seedlings are generally divided into pot seedlings and blanket seedlings[11]. With the standardized cultivation methods being recognized， pot seedlings have been valued because of the advantages of rapid seedling recovery， uniform seedling growth and effective yield improvement[12]. In the practice of dry??cultivated rice planting， the transplanting of pot seedlings can bring in complete roots and more seedling substrates， which is the preferred scheme for mechanized planting. In this study， the effects of soil moisture content， pot seedling buried depth and pot seedling height on the transplanting of seedlings are studied. The results show that the survival rate and growth of seedlings increase with the increase of soil moisture content， but the change is not significant when the soil moisture content is over 85%. When the pot seedling buried depth is smaller than 2 cm， the survival rate and growth of seedlings increase with the increase of buried depth， both of which achieve the best effects at the buried depth of 2 cm， while the indicators decrease when the buried depth is deeper than 2 cm. The survival rate and growth of seedlings are the best at the pot seedling height of 14 cm， and the survival rate and growth are affected if the pot seedlings are too high or too short. Therefore， the optimized conditions for dry??cultivated rice seedling planting are soil moisture content of 85%， pot seedling buried depth of 2 cm， and pot seedling height of 15 cm.
References
[1] WU X， YANG LQ， CHEN F， et al. Current status and development countermeasures of rice production in Shandong Province[J]. Shandong Agricultural Sciences， 2013， 45（5）： 119-125.
[2] SHEN CJ， HAN XH， YU L. The situation and development trend of rice cultivation mechanization technology at home and abroad[J]. Journal of Agricultural Mechanization Research， 2010（12）： 240-243.
[3] CHENG WD， ZHANG GP， ZHAO GP， et al. Differences in accumulation and translocation of the nutrients and dry matter between dry and paddy cultures of rice cultivar Jiazao 935[J]. Acta Agronomica Sinica， 2003， 29（3）： 413-418.
[4] CHENG JP， LUO XW， FAN QZ， et al. Influence of different planting methods on growth and development characteristics and yield of rice[J]. Journal of Huazhong Agricultural University （Natural Science Edition）， 2010， 29（1）： 1-5.
[5] DENG ZM， ZHAN BQ. Effects of different seedling ages on yield traits of hybrid late rice[J]. Fujian Science and Technology of Rice and Wheat， 2000（3）： 15-17.
[6] WANG JX， WANG DL， CHEN LH. Experimental study of yield response to maturity and transplanting time of rice seedling[J]. Irrigation and Drainage， 2000， 19（2）： 29-31.
[7] FANG SJ. Experimental study on relationship between dry age and yield[J]. China Agricultural Information， 2017（8）： 61-63.
[8] XIE SH， LI HM， LUO HL. Studies of seedling??raising methods on the growth and yield composition of late hybrid rice[J]. Crop Research， 2003（2）： 78-80.
[9] ZHANG YP， DU RC， DIAO PS， et al. Experiment of non??tillage and drought direct sowing rice and feasibility analysis in Shandong Province[J]. Transactions of the Chinese Society of Agricultural Engineering， 2016， 32（12）： 24-30.
[10] XIN MJ， REN WT， SONG YQ， et al. Effects of rice direct seeding on growth and yield[J]. Journal of Shenyang Agricultural University， 2014， 45（2）： 175-179.
[11] CHENG JP， WU JP， LUO XW， et al. Influence of different planting methods on growth characteristics and yield of early rice[J]. Hubei Agricultural Sciences， 2011， 50（3）： 457-460.
[12] ZHANG HC， ZHU CC， HUO ZY， et al. Advantages of yield formation and main characteristics of physiological and ecological in rice with nutrition bowl mechanical transplanting[J]. Transactions of the Chinese Society of Agricultural Engineering， 2013， 29（21）： 50-59.