| With the shortage of water resources and the increase of labor costs,dry direct seeding has become the main way of rice production at present.There are mainly two types of rice drought direct seeding:moisture retention and post-sowing water supply.After sowing in Ningxia Irrigation District,the water supply is affected by the time given by the Yellow River water.The sowing date is later,which affects the growth period of rice.Dry direct seeding with soil moisture conservation has become the main development direction.In order to select the suitable planting method and seeding rate in the Yellow River Irrigation Area,Ningjing 47 was used as experimental material.Four planting methods were set up:drill seeding,hole seeding(20cmx8cm),hole seeding(20cmx 12.5cm)and uniform seeding 10.4 kg/667m2,14.6 kg/667m2 and 18.8 kg/667m2.The effects of four planting methods and three sowing rates on the growth and development,physiological characteristics,nutrient absorption characteristics,yield and quality of rice were compared and analyzed.Suitable planting methods and sowing rates of rice were put forward to provide theoretical basis for high quality and high yield of direct seeding rice in Ningxia.The Results show that:1.Compared with different planting methods and different sowing rates,the method of hole sowing(20cmx 12.5cm)can increase the emergence rate,plant height and tiller number,and the method of uniform sowing is beneficial to increase leaf area index and dry matter weight,but there is no significant difference among the four planting methods.With the increase of seeding rate,the emergence rate decreased,plant height did not change,leaf area index increased,dry matter weight and tiller number changed differently.The interaction between planting pattern and seeding rate had no significant effect on the growth and development of rice.In the early stage of rice growth,Pn increased by 52.2%,62.7%,63.6%in the way of hole sowing(20cmx8cm),and SPAD increased by 0.3%,32.2%,10.1%in the way of uniform sowing(20cmx12.5cm).Compared with the other three planting methods,the transpiration rate(Tr)and stomatal conductance(Gs)of the two planting methods increased by 45.9%,16.4%,17.1%and 83.7%,51.6%,43.8%respectively.Compared with the other three planting methods,the transpiration rate(PI)of the hole seeding(20cmx8cm)increased by 26.0%,17.1%Compared with the other three planting patterns,the PAR value of the upper layer of uniform sowing pattern was 6.5%,16.2%,11.0.There were significant differences among the four planting methods.Compared with the other three planting patterns,the late drilling pattern was beneficial to the increase of photosynthesis by 52.0%,45.4%and 52.5%,respectively.Compared with the other three planting patterns,the uniform planting pattern was beneficial to the increase of SPAD by 16.4%,42.1%and 20.2%,respectively.21.The PAR value in the upper soil layer of hole seeding(20cmx8cm)was 20.8%,39.7%,40.5%higher than that of the other three planting patterns.With the increase of seeding rate,the overall trend of the various parameters of physiological indicators was reduced.With the increase of the number of days after emergence,the interaction between planting methods and sowing rates had a very significant effect on Pn,Ci,Tr,Gs and SPAD,but had no significant effect on PI and PAR.2.Compared with the four planting methods,the yield of uniform sowing is higher than the other three planting methods,and there is a significant difference between them.The highest yield was 712.24kg/667m2 under uniform seeding rate of 18.8kg/667m2,and there was no significant difference among the three seeding rates.Among the yield factors,the spike length was the highest(18.3cm)of 10.4kg/667m2 in the hole sowing(20cmx8cm)model.The number of spikes per mu is the highest of 18.8kg/667m2 in the model of hole sowing(20cmx8cm),reaching 4125000 spikes.The number of grains per ear is the highest of 14.6kg/667m2 and 18.8kg/667m2 in the model of row seeding,both of which were 117.5.The weight of 1000 grains is the highest of 10.4kg/667m2 in the model of uniform seeding,which was 25.06g.There was no significant difference between the interaction of planting pattern and seeding rate on the agronomic traits and yield of rice.3.Four planting methods had different effects on rice quality.The method of drilling was beneficial to the increase of brown rice rate and milled rice rate.The highest brown rice rate and milled rice rate were 83.42%and 77.11%respectively when the sowing rate was 18.8kg/667m2.The uniform sowing method was beneficial to the increase of head rice rate and protein content of brown rice,and the highest head rice rate was 67.52%when the sowing rate was 14.6kg/667m2;The protein content of 18.8kg/667m2 brown rice was the highest,which was 4.87%.The rate of chalkiness and chalkiness degree of rice sown with uniform sowing rate were the lowest,which were 5.5%and 1.0%respectively.The interaction of planting method and sowing rate had no significant difference on brown rice rate and milled rice rate,but had significant effect on other quality indexes of rice.4.The nutrient situation of rice plants in four planting methods.The results showed that the total nitrogen content of 18.8kg/667m2 was higher in the high sowing rate of hill sowing(20cmx12.5cm)in the early and middle stage of rice growth,while the total nitrogen content of 10.4kg/667m2 was lower in the low sowing rate of hill sowing(20cmx8cm).In the later period,the total nitrogen content of the four planting methods decreased and was at a low level,and there were significant differences among the four planting methods.The total phosphorus content was higher in the low sowing rate of 10.4kg/667m2 in drill sowing,and lower in the low sowing rate of 10.4kg/667m2 in hill sowing(20cmx 12.5cm).There were significant differences among the four planting methods.The total potassium content of 14.6kg/667m2 was higher in hole seeding(20cmx12.5cm),and 14.6kg/667m2 was lower in drill seeding,and there were significant differences among the four planting patterns.With the increase of the number of days after emergence,the interaction between planting methods and sowing rates had a significant effect on the contents of total nitrogen,total phosphorus and total potassium in rice plant.According to the comprehensive analysis,the way of hole seeding(20cmx12.5cm)is more conducive to promote the absorption of nitrogen,phosphorus and potassium in rice plants. |
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