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Abstract In order to explore the interaction effects of line spacing and seedling belt width on wheat yield formation and improve the cultivation techniques of broad-width and fine seeding of wheat, a high-yielding winter wheat cultivar Shannong 28 was selected as material. Using the split plot design, the main plot was set with line spacing as 20, 25 and 30 cm, respectively, and the sub-plot was set with seedling belt width as 3, 5, 7, 9 and 11 cm, respectively. Then, the population dynamics, dry matter accumulation and translocation and yield of wheat were studied under the experimental conditions. The results showed that under the line spacing of 20 cm, the dry matter accumulation and yield of winter wheat were higher with the seedling belt width of 5 cm. When the line spacing was 25 cm, the dry matter accumulation and yield under the seedling belt width of 9 cm reached a high level. Under the line spacing of 30 cm, Shannong 28 achieved higher dry matter accumulation and yield with the seedling belt width of 11 cm. Comprehensive analysis revealed that the suitable treatment for Shannong 28 was 25 cm of line spacing with 9 cm of seedling belt width, which could realize the coordination of the three factors of yield composition and get higher yield. Therefore, the reasonable line spacing and seedling belt width were the important technical ways to realize high yield of wheat.
Key words Winter wheat; Wide planting; Row space form; Seedling belt width; Yield
Received: November 2, 2019Accepted: January 1, 2019
Supported by National Key R&D Program of China (2017YFD0301001); Shandong Province Modern Agricultural Technology Wheat Innovation Team (SDAIT-04-022, SDAIT-01-08); Agricultural Scientific and Technological Innovation project of Shandong Academy of Agricultural Sciences (CXGC2016B01).
Minmin SHAO (1982-), female, P. R. China, agronomist, devoted to research about wheat genetic breeding and cultivation.
*Corresponding author. E-mail: mmshao729@163.com.
Broad-width fine sowing cultivation of wheat is a new yield-increasing technology in wheat production. Its main characteristic is to change the traditional dense sowing from small row spacing (15-20 cm) to large row spacing (22-26 cm), by which the sown grains is changed from the distribution of crowding into a line to a belt distribution［1］. Studies have shown that broad-width fine sowing of wheat can evenly distribute wheat seeds, effectively reduce the phenomena of lacking seedlings and crowded seedlings, and overcome the shortcomings of overcrowded seeds, individual competition for fertilizer and water, few roots, weak seedlings, and unbalanced individual development caused by seeding in line. It also has a good promotion role in cultivating strong seedlings before winter and enhancing photosynthetic capacity［2-3］. The current reports of broad-width fine sowing of wheat are limited to the advantages of broad width compared with conventional sowing in line［4］, and the effects of different line spacing and densities on wheat yield［5-7］. However, the effects of the interaction between line spacing and seedling belt width on wheat population development and yield formation under broad-width conditions have not been reported. In this study, wheat cultivar Shannong 28 was selected as an experimental material and sown in field under three line spacing levels (20, 25 and 30 cm) and five sowing widths (3, 5, 7, 9 and 11 cm) to form different line spacing and seedling belt width configurations, and the effects of their interaction effects on wheat population and yield formation were analyzed, so as to clarify the yield increasing mechanism of the broad-width fine sowing technology and determine the optimal seedling belt width and row spacing configuration. This study provides theoretical basis and supporting technical measures for broad-width high-yielding wheat cultivation.
Materials and Methods
Experimental materials
The experiment was carried out continuously in 2016-2017 and 2017-2018 at the test farm of Jining Academy of Agricultural Sciences. The soil tested was brown soil containing organic matter content 10.76 g/kg, total nitrogen 0.95 g/kg, alkali-hydrolyzable nitrogen 75.1 mg/kg, available phosphorus 46.92 mg/kg and rapidly available potassium 62.56 mg/kg with a pH value of 5.97. The experiment wheat cultivar was Shannong 28.
Experimental design and management
The experiment adopted a split plot design, in which the line spacing was the main plot which was wet with such three line spacing levels as 20 (S1), 25 (S2) and 30 cm (S3), and the seedling belt width was the sub-plot which was set with such five seedling belt widths as 3 (B1), 5 (B2), 7 (B3), 9 (B4) and 11 cm (B5). There were a total of 15 treatments, and the plot area was 30 m2. The various treatments were in randomized block arrangement and repeated 3 times. Before sowing wheat seeds, corn stalks were pulverized and then returned to the field, followed by deep plowing. Fertilization was performed at N 105 kg, P2O5 105 kg, and K2O 120 kg per hectare before plowing. The seeds were sown on October 18 by the artificial simulation method, which includes the steps of ditching with a ditcher after rowing with a rower, then using a shaper to shape the ditches to meet different seeding belt widths, manually spreading the seeds evenly in the seedling belts, covering the seeds with the soil and raking to level the soil. The sowing depth of each treatment was 3 to 5 cm, and the basic seedlings were 2.25 million/hm2. Topdressing was performed with N 105 kg/hm2 during jointing. Other field management was carried out in accordance with local high-yield field standards. The results of the two years were basically the same. Determination items and methods
Investigation of population dynamics in each growth stage
A fixed-point method was used to investigate the dynamics of wheat populations. Representative double-row fixed sampling points with a length of 1 m were selected in each plot in the three-leaf stage, and the population dynamics were investigated in the key growth stages of wintering, greening, jointing and flowering.
Dry matter accumulation and distribution
Thirty plants with uniform growth were taken from each plot to determine the dry matter weight at overwintering, returning green and jointing stages, and 30 single stems with uniform growth were randomly selected from each plot to determine the dry matter weight at reproductive stages (flowering and maturation stages). The samples at flowering stage were divided into three parts (stalk+leaf sheath, leaf, spike), and the samples at maturation stage were divided into four parts (stalk+leaf sheath, leaf, spike axis+glume, grain). After sampling, the samples were placed in an oven at 105 ℃ for 15 min, and then dried at 80 ℃ to constant weight. With reference to the method of Hu et al. ［8］, the translocation of dry matter stored in vegetative organs before flowering, the translocation efficiency of dry matter stored in vegetative organs before flowering, the contribution rate of dry matter stored in vegetative organs before flowering to grain yield, the translocation proportion of dry matter in seeds after flowering and the distribution rate of dry matter after flowering to grain yield were calculated.
Determination of wheat yield and its components at maturation stage
The number of seeds per spike, thousand-kernel weight and number of spikes per hectare were investigated. Plants in an area of 5 m2 were harvested from each plot, followed by threshing and air-drying. The weight was measured until the moisture content was about 13%, and converted to yield per hectare.
Data processing
The experimental data was statistically analyzed using Microsoft Excel 2003 software, and the significance test of differences was performed using DPS 7.05 software.
Results and Analysis
Effects of different line spacing and seedling belt widths on dynamic changes of wheat population
It can be known from Table 1 that the population numbers of the winter wheat in different treatments showed a trend of first increasing and then decreasing during the growth period, and all reached a peak during the jointing stage. The population number of winter wheat under the same line spacing increased with the increase of the width of the planted seedling belt from the overwintering stage to the jointing stage; and the population number of winter wheat under the same seedling belt width decreased with the increase of the planting spacing. This shows that the population number of wheat can be adjusted by setting different line spacing and seedling belt widths. Effects of different line spacing and seedling belt widths on dry matter accumulation of wheat population
The dry matter accumulation of the winter wheat population increased with the progress of the growth period. It grew slowly from overwintering to jointing stage, and then rapidly from jointing to maturation stage (Table 2). Under the 20 cm line spacing, the dry matter accumulation in each growth stage was the highest with the treatment of the seedling belt width of 7 cm. Under the 25 cm line spacing, with the increase of the seedling belt width, the dry matter accumulation increased first and then decreased, and it reached the highest value in maturation stage in the treatment of the seedling belt width of 9 cm, but was highest in all other stages when the seedling width of 7 cm. Under the 30 cm line spacing, the dry matter accumulation was highest in overwintering, returning green and jointing stages when the belt width was 9 cm, but reached the highest value in flowering and maturation stages in the treatment of the belt width of 11 cm; and in flowering and maturation stages, the amounts of dry matter accumulation in the treatment of the belt width of 11 cm were the largest, followed by those in the treatment of the belt width of 9 cm, and the differences were significant.
Effects of interaction between different line spacing and seedling belt widths on dry matter allocation in wheat in maturation stage
At the maturation stage of wheat, the dry matter accumulation and allocation proportions of different organs were all expressed as grain＞stalk+leaf sheath＞spike axis+glume＞leaf, and dry matter accumulation in grains accounted for more than half of the total accumulation (Table 3). Under the line spacing of 20 cm, the dry matter accumulation amounts of all organs except spike axis+glume were the largest when the seedling belt width was 7 cm, accompanied by higher allocation proportions; and the differences in dry matter accumulation amount and allocation proportion were not significant mostly between other treatments. Under the line spacing of 25 cm, with the increase of the seedling belt width, the dry matter accumulation of grains first increased and then decreased, and was the largest in the treatment of the seedling belt width of 9 cm, which showed the dry matter allocation proportion equivalent to other treatments; and the dry matter accumulation amounts of stalks and spike axes were also maximum with the seedling belt width of 9 cm. Under the line spacing of 30 cm, with the increase of the seedling band width, the dry matter accumulation of grains showed an increasing trend, and reached the largest value when the width of the seedling belt was 11 cm in width, accompanied by a higher allocation proportion. Minmin SHAO et al. Effects of Different Line Spacing and Seedling Belt Width on Yield Formation of Broad-Width Fine Sowing Wheat
Effects of different line spacing and seedling widths on dry matter reallocation of vegetative organs after flowering and its contribution to grains
As shown in Table 4, under the line spacing of 20 cm, with the increase of the seedling belt width, the translocation of dry matter stored before flowering from the vegetative organs to grains showed a trend of first increasing and then decreasing, and it was the largest with the seedling belt width of 7 cm and was significantly larger at 5, 7, 9 and 11 cm than at the seedling belt width of 3 cm; and after flowering, the dry matter accumulation in grains appeared to rise first and then decrease, and the maximum appeared at 7 cm. Under the line spacing of 25 cm, with the increase of the width of the seedling belt, the translocation of dry matter stored before flowering from the vegetative organs to grains and the accumulation of dry matter in grains after flowering both appeared to rise first and then decrease, and were the largest when the width of the seedling belt was 9 cm. Under the line spacing of 30 cm, with the increase of the seedling belt width, the translocation of dry matter stored before flowering from vegetative organs to grains increased first and then decreased slightly; and the accumulation of dry matter in grains after flowering was highest in the treatment of the seedling belt width of 11 cm, without a significant difference from the 9 cm treatment.
Effects of interaction between different line spacing and seedling belt widths on wheat yield and its components
It can be known from Table 5 that under the line spacing of 20 cm, with the increase of the width of the seedling belt, the number of spikes of winter wheat generally increased first and then decreased, and the number of seeds per spike and thousand-kernel weight increased and were significantly affected; and the grain yield showed a trend of increasing first and decreasing then, and was the highest when the seedling belt width was 7 cm. When the line spacing was 25 cm, with the increase of the seedling belt width, the number of spikes and the number of seeds per spike of winter wheat increased first and then decreased, and there was also a significant effect on the thousand-kernel weight; and the grain yield was highest when the seedling width was 9 cm. When the row spacing was 30 cm, the number of spikes and grain yield of winter wheat showed an increasing trend with the increase of the seedling belt width, and the seed yield was highest when the seedling width was 11 cm; and the seeding belt width had a significant effect on the number of seeds per spike, but no significant effect on thousand-kernel weight. According to comprehensive analysis, the yield of wheat was higher under the planting line spacing of 25 cm configured with a seedling belt width of 9 cm and the planting line spacing of 30 cm configured with a seedling belt width of 11 cm.
Discussion and Conclusions
Previous studies have shown that dry matter accumulation is the material basis for wheat yield formation. Dry matter synthesized by wheat is mainly used for morphogenesis during the vegetative growth stage, and dry matter accumulation after flowering is mainly used for grain growth and development of grains, which is especially important to the increase of yield. In a certain range, the yield increases significantly with the increase of dry matter accumulation after flowering［9-10］. Some scholars believe that narrower line spacing can increase leaf area and extinction coefficient at the same density. In a certain range, the leaf area index is positively correlated to the light interception. Therefore, the light interception capacity of narrow line spacing is 25%-35% higher than that of wide line spacing. Plant line spacing configuration can also improve the ventilation and light transmission conditions of the populations after flowering［11］. With the row spacing increasing and the plant spacing decreasing, canopy light interception decreases and the light transmittance increases［12］. The results of this study indicate that under different planting line spacing and seedling band width configurations, narrow line spacing configured with a small seedling belt width and wide line spacing configured with a large seedling belt width are beneficial to the accumulation of dry matter in wheat and the contribution of dry matter stored in vegetative organs before and after flowering to grain yield. Under the conditions of this study, the highest translocation of dry matter accumulated before and after flowering in Shannong 28 to seeds was observed in the configuration of the planting line spacing of 25 cm and the seedling belt width of 9 cm.
Wheat yield is composed of number of spike per unit area, number of seeds per spike and thousand-kernel weight, which affects each other. Under normal circumstances, the number of seeds per spike and thousand-kernel weight are greatly affected by the variety, while the number of spikes is greatly affected by the line spacing and plant spacing. Line and plant spacing configuration largely determines the population structure and uniformity of wheat, and affects light utilization, dry matter accumulation and yield formation of wheat［13-14］. In production, a proper line spacing under reasonable dense planting can effectively adjust the dynamics of the crop population, and make the plants nutritional area uniformly distributed, the leaf position extended and coordinated and the photosynthetic capacity improved. Liu et al. ［15］ showed that although a wide line spacing can improve the marginal effect, it has serious light leakage and low total production capacity; and under a too narrow line spacing, there might be problems such as poor ventilation and light transmission ability, mutually shaded leaves, decreased photosynthetic capacity, reduced dry matter accumulation and reduced yield. The results of this study shows that under the same line spacing, with the width of the planted seedling belt increasing, the number of spikes per unit area increases first and then decreases, and when the width of seedling belt increases to a certain value, a suitable line spacing must be configured, that is, a high wheat yield can only be achieved with narrow line spacing and small seedling belt, or wide line spacing and large seedling belt. Therefore, a reasonable seedling width and line spacing configuration is conducive to improving the uniformity of wheat population distribution and alleviating the contradiction between population and individuals, and is an important way to achieve a high wheat yield. Under the conditions of this study, a comprehensive analysis suggests that the reasonable planting configuration of Shannong 28 was row spacing of 25 cm configured with seedling belt width of 9 cm, or row spacing of 30 cm configured with seedling belt width of 11 cm. References
［1］ DANG W, MA C, ZHAO Q, et al. Effect of wide precision seeding on the yield and yield components of wheat［J］. Journal of Hebei Agricultural Sciences, 2015, 19(2): 15-17. (in Chinese)
［2］ ZHAO BQ, YU SL, LI FC, et al. Study on belt shape-population-yield-related laws of belt-planted wheat［J］. Scientia Agricultura Sinica, 1999, 32(1): 33-39. (in Chinese)
［3］ LI SY, FENG W, WANG YH, et al. Effects of spacing interval of wide bed planting on canopy characteristics and yield in winter wheat［J］. Chinese Journal of Plant Ecology, 2013, 37(8): 758-767. (in Chinese)
［4］ ZHAO HB, YU K, QU RT, et al. Effects of wide precision sowing on population dynamics and yield of winter wheat［J］. Bulletin of Agricultural Science and Technology, 2012(6): 42-45. (in Chinese)
［5］ WU YE, GAO QL, XUE X. Effects of line spacing on canopy structure and yield components of super-high-yield wheat［J］. Journal of Henan Agricultural Sciences, 2005(9): 16-20. (in Chinese)
［6］ ZHANG QG, MA RK, JIA XL, et al. Effect of planting density and pattern on yield and yield components different high-gluten winter wheat［J］. Journal of Hebei Agricultural Sciences, 2006, 10 (2):11-15. (in Chinese)
［7］ FENG W, LI SY, WANG YH, et al. Effects of spacing intervals on the ageing process and grain yield in winter wheat under wide bed planting methods［J］. Acta Ecologica Sinica, 2015, 35(8): 2686-2694. (in Chinese)
［8］ HU MY, ZHANG ZB, XU P, et al. Relationship of water use efficiency with photoassimilate accumulation and transport in wheat under deficit irrigation［J］. Acta Agronomica Sinica, 2007, 33(11): 1884-1891. (in Chinese)
［9］ HUANG YS, ZHANG HC, XU K, et al. Effects of the quantities of nitrogenous fertilizer on the yield and population quality of the mid-gluten wheat Yangmai 11［J］. Chinese Agricultural Science Bulletin, 2006, 24(10): 238-241. (in Chinese)
［10］ WANG CN, WU DY, XIA XY, et al. Influence of density on population quality and yield of wheat Jinan 17 under high fertilizer condition［J］. Jiangsu Agricultural Sciences, 2002(1): 18-19. (in Chinese)
［11］ ZENG ZR, ZHAO SN, LI Q. Canopy development, light interception and grain yield in high yielding wheat varieties in Beijing District［J］. Acta Agronomica Sinica, 1991, 17(3): 161-170. (in Chinese)
［12］ YANG WP, GUO TC, LIU SB, et al. Effects of row spacing configuration on the canopy structure and microenvironment of ‘Lankao Aibazao’ wheat population［J］. Chinese Journal of Plant Ecology, 2008, 32(2): 485-490. (in Chinese)
［13］ YANG WP, GUO TC, FENG W, et al. Effects of row spacing on photosynthetic characteristics and yield of two winter wheat cultivars with different spike types［J］. Journal of Triticeae Crops, 2012, 32(3): 494-499. (in Chinese)
［14］ YIN FW, WANG WX, GU XB, et al. Effect of planting distance configuration repression on wheat yield formation with wide planting［J］. Journal of Triticeae Crops, 2018, 38 (6): 710-717. (in Chinese)
［15］ LIU LP, HU HH, LI RQ, et al. Effects of spacing configuration and density on population quality and yield of winter wheat variety Henong 822［J］. Acta Agriculturae Boreali-Sinica, 2008, 23(2): 125-131. (in Chinese)
Editor: Yingzhi GUANGProofreader: Xinxiu ZHU
Key words Winter wheat; Wide planting; Row space form; Seedling belt width; Yield
Received: November 2, 2019Accepted: January 1, 2019
Supported by National Key R&D Program of China (2017YFD0301001); Shandong Province Modern Agricultural Technology Wheat Innovation Team (SDAIT-04-022, SDAIT-01-08); Agricultural Scientific and Technological Innovation project of Shandong Academy of Agricultural Sciences (CXGC2016B01).
Minmin SHAO (1982-), female, P. R. China, agronomist, devoted to research about wheat genetic breeding and cultivation.
*Corresponding author. E-mail: mmshao729@163.com.
Broad-width fine sowing cultivation of wheat is a new yield-increasing technology in wheat production. Its main characteristic is to change the traditional dense sowing from small row spacing (15-20 cm) to large row spacing (22-26 cm), by which the sown grains is changed from the distribution of crowding into a line to a belt distribution［1］. Studies have shown that broad-width fine sowing of wheat can evenly distribute wheat seeds, effectively reduce the phenomena of lacking seedlings and crowded seedlings, and overcome the shortcomings of overcrowded seeds, individual competition for fertilizer and water, few roots, weak seedlings, and unbalanced individual development caused by seeding in line. It also has a good promotion role in cultivating strong seedlings before winter and enhancing photosynthetic capacity［2-3］. The current reports of broad-width fine sowing of wheat are limited to the advantages of broad width compared with conventional sowing in line［4］, and the effects of different line spacing and densities on wheat yield［5-7］. However, the effects of the interaction between line spacing and seedling belt width on wheat population development and yield formation under broad-width conditions have not been reported. In this study, wheat cultivar Shannong 28 was selected as an experimental material and sown in field under three line spacing levels (20, 25 and 30 cm) and five sowing widths (3, 5, 7, 9 and 11 cm) to form different line spacing and seedling belt width configurations, and the effects of their interaction effects on wheat population and yield formation were analyzed, so as to clarify the yield increasing mechanism of the broad-width fine sowing technology and determine the optimal seedling belt width and row spacing configuration. This study provides theoretical basis and supporting technical measures for broad-width high-yielding wheat cultivation.
Materials and Methods
Experimental materials
The experiment was carried out continuously in 2016-2017 and 2017-2018 at the test farm of Jining Academy of Agricultural Sciences. The soil tested was brown soil containing organic matter content 10.76 g/kg, total nitrogen 0.95 g/kg, alkali-hydrolyzable nitrogen 75.1 mg/kg, available phosphorus 46.92 mg/kg and rapidly available potassium 62.56 mg/kg with a pH value of 5.97. The experiment wheat cultivar was Shannong 28.
Experimental design and management
The experiment adopted a split plot design, in which the line spacing was the main plot which was wet with such three line spacing levels as 20 (S1), 25 (S2) and 30 cm (S3), and the seedling belt width was the sub-plot which was set with such five seedling belt widths as 3 (B1), 5 (B2), 7 (B3), 9 (B4) and 11 cm (B5). There were a total of 15 treatments, and the plot area was 30 m2. The various treatments were in randomized block arrangement and repeated 3 times. Before sowing wheat seeds, corn stalks were pulverized and then returned to the field, followed by deep plowing. Fertilization was performed at N 105 kg, P2O5 105 kg, and K2O 120 kg per hectare before plowing. The seeds were sown on October 18 by the artificial simulation method, which includes the steps of ditching with a ditcher after rowing with a rower, then using a shaper to shape the ditches to meet different seeding belt widths, manually spreading the seeds evenly in the seedling belts, covering the seeds with the soil and raking to level the soil. The sowing depth of each treatment was 3 to 5 cm, and the basic seedlings were 2.25 million/hm2. Topdressing was performed with N 105 kg/hm2 during jointing. Other field management was carried out in accordance with local high-yield field standards. The results of the two years were basically the same. Determination items and methods
Investigation of population dynamics in each growth stage
A fixed-point method was used to investigate the dynamics of wheat populations. Representative double-row fixed sampling points with a length of 1 m were selected in each plot in the three-leaf stage, and the population dynamics were investigated in the key growth stages of wintering, greening, jointing and flowering.
Dry matter accumulation and distribution
Thirty plants with uniform growth were taken from each plot to determine the dry matter weight at overwintering, returning green and jointing stages, and 30 single stems with uniform growth were randomly selected from each plot to determine the dry matter weight at reproductive stages (flowering and maturation stages). The samples at flowering stage were divided into three parts (stalk+leaf sheath, leaf, spike), and the samples at maturation stage were divided into four parts (stalk+leaf sheath, leaf, spike axis+glume, grain). After sampling, the samples were placed in an oven at 105 ℃ for 15 min, and then dried at 80 ℃ to constant weight. With reference to the method of Hu et al. ［8］, the translocation of dry matter stored in vegetative organs before flowering, the translocation efficiency of dry matter stored in vegetative organs before flowering, the contribution rate of dry matter stored in vegetative organs before flowering to grain yield, the translocation proportion of dry matter in seeds after flowering and the distribution rate of dry matter after flowering to grain yield were calculated.
Determination of wheat yield and its components at maturation stage
The number of seeds per spike, thousand-kernel weight and number of spikes per hectare were investigated. Plants in an area of 5 m2 were harvested from each plot, followed by threshing and air-drying. The weight was measured until the moisture content was about 13%, and converted to yield per hectare.
Data processing
The experimental data was statistically analyzed using Microsoft Excel 2003 software, and the significance test of differences was performed using DPS 7.05 software.
Results and Analysis
Effects of different line spacing and seedling belt widths on dynamic changes of wheat population
It can be known from Table 1 that the population numbers of the winter wheat in different treatments showed a trend of first increasing and then decreasing during the growth period, and all reached a peak during the jointing stage. The population number of winter wheat under the same line spacing increased with the increase of the width of the planted seedling belt from the overwintering stage to the jointing stage; and the population number of winter wheat under the same seedling belt width decreased with the increase of the planting spacing. This shows that the population number of wheat can be adjusted by setting different line spacing and seedling belt widths. Effects of different line spacing and seedling belt widths on dry matter accumulation of wheat population
The dry matter accumulation of the winter wheat population increased with the progress of the growth period. It grew slowly from overwintering to jointing stage, and then rapidly from jointing to maturation stage (Table 2). Under the 20 cm line spacing, the dry matter accumulation in each growth stage was the highest with the treatment of the seedling belt width of 7 cm. Under the 25 cm line spacing, with the increase of the seedling belt width, the dry matter accumulation increased first and then decreased, and it reached the highest value in maturation stage in the treatment of the seedling belt width of 9 cm, but was highest in all other stages when the seedling width of 7 cm. Under the 30 cm line spacing, the dry matter accumulation was highest in overwintering, returning green and jointing stages when the belt width was 9 cm, but reached the highest value in flowering and maturation stages in the treatment of the belt width of 11 cm; and in flowering and maturation stages, the amounts of dry matter accumulation in the treatment of the belt width of 11 cm were the largest, followed by those in the treatment of the belt width of 9 cm, and the differences were significant.
Effects of interaction between different line spacing and seedling belt widths on dry matter allocation in wheat in maturation stage
At the maturation stage of wheat, the dry matter accumulation and allocation proportions of different organs were all expressed as grain＞stalk+leaf sheath＞spike axis+glume＞leaf, and dry matter accumulation in grains accounted for more than half of the total accumulation (Table 3). Under the line spacing of 20 cm, the dry matter accumulation amounts of all organs except spike axis+glume were the largest when the seedling belt width was 7 cm, accompanied by higher allocation proportions; and the differences in dry matter accumulation amount and allocation proportion were not significant mostly between other treatments. Under the line spacing of 25 cm, with the increase of the seedling belt width, the dry matter accumulation of grains first increased and then decreased, and was the largest in the treatment of the seedling belt width of 9 cm, which showed the dry matter allocation proportion equivalent to other treatments; and the dry matter accumulation amounts of stalks and spike axes were also maximum with the seedling belt width of 9 cm. Under the line spacing of 30 cm, with the increase of the seedling band width, the dry matter accumulation of grains showed an increasing trend, and reached the largest value when the width of the seedling belt was 11 cm in width, accompanied by a higher allocation proportion. Minmin SHAO et al. Effects of Different Line Spacing and Seedling Belt Width on Yield Formation of Broad-Width Fine Sowing Wheat
Effects of different line spacing and seedling widths on dry matter reallocation of vegetative organs after flowering and its contribution to grains
As shown in Table 4, under the line spacing of 20 cm, with the increase of the seedling belt width, the translocation of dry matter stored before flowering from the vegetative organs to grains showed a trend of first increasing and then decreasing, and it was the largest with the seedling belt width of 7 cm and was significantly larger at 5, 7, 9 and 11 cm than at the seedling belt width of 3 cm; and after flowering, the dry matter accumulation in grains appeared to rise first and then decrease, and the maximum appeared at 7 cm. Under the line spacing of 25 cm, with the increase of the width of the seedling belt, the translocation of dry matter stored before flowering from the vegetative organs to grains and the accumulation of dry matter in grains after flowering both appeared to rise first and then decrease, and were the largest when the width of the seedling belt was 9 cm. Under the line spacing of 30 cm, with the increase of the seedling belt width, the translocation of dry matter stored before flowering from vegetative organs to grains increased first and then decreased slightly; and the accumulation of dry matter in grains after flowering was highest in the treatment of the seedling belt width of 11 cm, without a significant difference from the 9 cm treatment.
Effects of interaction between different line spacing and seedling belt widths on wheat yield and its components
It can be known from Table 5 that under the line spacing of 20 cm, with the increase of the width of the seedling belt, the number of spikes of winter wheat generally increased first and then decreased, and the number of seeds per spike and thousand-kernel weight increased and were significantly affected; and the grain yield showed a trend of increasing first and decreasing then, and was the highest when the seedling belt width was 7 cm. When the line spacing was 25 cm, with the increase of the seedling belt width, the number of spikes and the number of seeds per spike of winter wheat increased first and then decreased, and there was also a significant effect on the thousand-kernel weight; and the grain yield was highest when the seedling width was 9 cm. When the row spacing was 30 cm, the number of spikes and grain yield of winter wheat showed an increasing trend with the increase of the seedling belt width, and the seed yield was highest when the seedling width was 11 cm; and the seeding belt width had a significant effect on the number of seeds per spike, but no significant effect on thousand-kernel weight. According to comprehensive analysis, the yield of wheat was higher under the planting line spacing of 25 cm configured with a seedling belt width of 9 cm and the planting line spacing of 30 cm configured with a seedling belt width of 11 cm.
Discussion and Conclusions
Previous studies have shown that dry matter accumulation is the material basis for wheat yield formation. Dry matter synthesized by wheat is mainly used for morphogenesis during the vegetative growth stage, and dry matter accumulation after flowering is mainly used for grain growth and development of grains, which is especially important to the increase of yield. In a certain range, the yield increases significantly with the increase of dry matter accumulation after flowering［9-10］. Some scholars believe that narrower line spacing can increase leaf area and extinction coefficient at the same density. In a certain range, the leaf area index is positively correlated to the light interception. Therefore, the light interception capacity of narrow line spacing is 25%-35% higher than that of wide line spacing. Plant line spacing configuration can also improve the ventilation and light transmission conditions of the populations after flowering［11］. With the row spacing increasing and the plant spacing decreasing, canopy light interception decreases and the light transmittance increases［12］. The results of this study indicate that under different planting line spacing and seedling band width configurations, narrow line spacing configured with a small seedling belt width and wide line spacing configured with a large seedling belt width are beneficial to the accumulation of dry matter in wheat and the contribution of dry matter stored in vegetative organs before and after flowering to grain yield. Under the conditions of this study, the highest translocation of dry matter accumulated before and after flowering in Shannong 28 to seeds was observed in the configuration of the planting line spacing of 25 cm and the seedling belt width of 9 cm.
Wheat yield is composed of number of spike per unit area, number of seeds per spike and thousand-kernel weight, which affects each other. Under normal circumstances, the number of seeds per spike and thousand-kernel weight are greatly affected by the variety, while the number of spikes is greatly affected by the line spacing and plant spacing. Line and plant spacing configuration largely determines the population structure and uniformity of wheat, and affects light utilization, dry matter accumulation and yield formation of wheat［13-14］. In production, a proper line spacing under reasonable dense planting can effectively adjust the dynamics of the crop population, and make the plants nutritional area uniformly distributed, the leaf position extended and coordinated and the photosynthetic capacity improved. Liu et al. ［15］ showed that although a wide line spacing can improve the marginal effect, it has serious light leakage and low total production capacity; and under a too narrow line spacing, there might be problems such as poor ventilation and light transmission ability, mutually shaded leaves, decreased photosynthetic capacity, reduced dry matter accumulation and reduced yield. The results of this study shows that under the same line spacing, with the width of the planted seedling belt increasing, the number of spikes per unit area increases first and then decreases, and when the width of seedling belt increases to a certain value, a suitable line spacing must be configured, that is, a high wheat yield can only be achieved with narrow line spacing and small seedling belt, or wide line spacing and large seedling belt. Therefore, a reasonable seedling width and line spacing configuration is conducive to improving the uniformity of wheat population distribution and alleviating the contradiction between population and individuals, and is an important way to achieve a high wheat yield. Under the conditions of this study, a comprehensive analysis suggests that the reasonable planting configuration of Shannong 28 was row spacing of 25 cm configured with seedling belt width of 9 cm, or row spacing of 30 cm configured with seedling belt width of 11 cm. References
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Editor: Yingzhi GUANGProofreader: Xinxiu ZHU