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Abstract [Objectives] This study was conducted to investigate the effect of silicon fertilizer on maize growth and Tetranychus truncatus Ehara.
[Methods] Yougui and Guishen were selected and sprayed onto maize for 1， 2 and 3 times， forming difference treatments.
[Results] Spraying the two kinds of silicon fertilizers for different times promoted the growth of plant height， leaf length， leaf width and leaf thickness of maize， increased chlorophyll contents in maize leaves and yield of single ear， and also adversely affected T. truncatus （i.e.， increased the death rate of T.truncatus）. The more the treatment times of silicon fertilizer， the more remarkable the effect， and the higher the adverse effect on T. truncatus.
[Conclusions] In production， spraying silicon fertilizer onto maize for 2-3 times could realize the purposes of increasing maize yield and alleviating the damage by T. truncatus.
Key words Silicon fertilizer； Maize； Growth； Tetranychus truncatus Ehara
Received： December 1， 2017 Accepted： January 5， 2018
Supported by College Students Innovation and Enterpreneurship Traning Program of Yanbian University （ydbksky2017507）.
Zhiru LIU （1966-）， male， P. R. China， bachelor ， major： environmental sciences.
*Corresponding author. Email： [email protected]
There is abundant silicon in the earths crust， and plants growing in soil contain different amounts of silicon[1]. As silicon exists widely and shows no remarkably insufficiency symptoms， the effect of silicon on plant growth does not attract peoples attention. With the continuous increase of plant physiological experiments， the importance of silicon in plant life is proved[2]. Silicon as a useful element for plants， could significantly promote the healthy growth of crops， and is proved to be a necessary element to eggplant and cucumber[3]. Silicon nutrient alleviates heavy metal toxicity and salt stress through the improvement of the structure of plant leaf. It not only improves the drought resistance and diseases resistance in plants， but also improvesthe resistance to pests in plants， thereby reducing the damage to crops by pests， and therefore， the economic output and quality agricultural quality are improved[4-5]. However， there were few studies on the effect of silicon fertilizer on the photosynthesis of maize[6].
Maize is a main upland crop planted in the Northeast China and North China. However， in recent years， maize is suffered from Ostrinia nubilalis， armyworm and spider mite， and especially from the end of last century， continuous drought happens in the north areas， Tetranychus truncatus Ehara occurs in the maizegrowing areas in the northern China continuously[7]. The damage to agricultural crops become more and more serious， and the loss rate caused by the damage reached 10%-30%， and the control of the pest has become an urgent affair[8-9]. For this， the effects of silicon fertilizer on maize growth and the occurrence of T. truncatus were discussed， so as to serve the production. Materials and Methods
Experimental materials
Silicon fertilizers
Yougui was produced by Nangong Huayang Chemical Plant， and Guishen was produced by Cheng Pu Fertilizer Industry.
Tested maize
The maize variety C was provided by professor Zheng from Genetic Breeding Laboratory， Agricultural College， Yanbian University.
Tested pests
T. truncatus was collected from the leaves of weeds in the greenhouse of Agricultural College， Yanbian University. The pests were fed and propagated on cowpea in laboratory. The pests were cultured at 23-27 ℃ under 16 （light） L∶8 （dark） D and a relative humidity of 50%-60%.
Experimental instruments
Electrodyne （3JWB16A）； plant chlorophyll meter （SYS02）； leaf thickness measuring instrument （LS3）； electronic scale （JMA2003）.
Experimental methods
Sowing of maize
On June 5， the field with poor fertility in the Agricultural College was turned over and ridged， and each hole was sown with 2 seeds according to a row placing of 60 cm and a plant spacing of 60 cm. On July 5， only one healthy plants was reserved in one hole.
Silicon fertilizer treatments
Each plot included 2 rows， each of which included 10 plants， and there were 20 maize plants in one plot. From July 20， silicon fertilizer treatment was performed every 10 d. Yougui and Guishen were diluted by 750 times， and sprayed with fertilizer onto the leaves with the electrodyne. In order to achieve well adsorption of the silicon fertilizers onto maize leaves， 2 000 times dilution of Tween 80 was added into the electrodyne. The experiment was designed with seven treatments， i.e.， control （CK）， Yougui1 （spraying Yougui once， similarly hereinafter）， Yougui 2 and Yougui 3， and Guishen 1， Guishen 2 and Guishen 3.
Investigation of maize growth
Plant height， leaf length and leaf width measurement
On September 2， the plant height of maize was measured with a measuring scale and recorded. During the measurement of leaf length and leaf width of maize， the leaf of ear was selected and measured， and the values were recorded.
Measurement of chlorophyll content and leaf thickness of maize
On August 20， the chlorophyll content and thickness of the leaf of ear were measured with the chlorophyll meter and the measuring instrument of leaf thickness， respectively. During the determination of chlorophyll， the measurement was performed at the same time period. During the measurement of leaf thickness， the same measurement position was selected when keeping away from leaf veins. Yield investigation of single ear of maize
Each ear was collected， and the grains were stripped off and added into a paper bag which was labeled. The grains were weighed one month later， and the values were recorded.
Investigation of T. truncatus
On August 15， a layer of sponge with a thickness of 1 cm was placed in a culture dish with a diameter of 12 cm， and a layer of degreasing cotton with a thickness of 1 mm was laid on the sponge. Water was added into the culture dish to the level of the sponge. Leaves were collected from the 7 treatments （CK， Yougui1， 2 and 3 and Guishen1， 2 and 3）， respectively. Leaf segments （2 cm×5 cm） were cut and placed on the degreasing cotton with the leaf back upward， and no spacing was reserved between the leaf segments and degreasing cotton. Onto each leaf segment， 10 pests were put with a fine brush. Into each culture dish， 3 leaf segments were placed at intervals between each other， as three replicates. Watering was performed on the 1st d and the 3rd d， and the death rate of T. truncatus was investigated and recorded on the 5th d.
Analysis software
The data were analyzed with DPS v7.05， and multiple comparisons were performed by Duncans new multiple range method.
Results and Analysis
Effects of the two silicon fertilizers on maize growth
It could be seen from Table 1 that Yougui 3， Yougui 2， Yougui 1 and Guishen 3 had the plant heights， respectively， of 182.0， 177.2， 175.4 and 157.0 cm， which were significantly higher than the plant height of the CK of 136.6 cm. With the treatment times increasing， the plant height also increased. It also could be seen that the Yougui treatment was better than the Guishen treatment， and the plant heights of Guishen 2 and Guishen 1 were not significantly different from that of the CK.
Table 1 Effects of the two silicon fertilizers on plant height， leaf length， leaf width and leaf thickness of maize
Treatment Plant height∥cmLeaf length∥cmLeaf width∥cmLeaf thickness∥mm
Yougui 3182.0 a64.9 a9.7 a0.286 4 a
Guishen 3157.0 b60.5 ab8.7 ab0.286 4 a
Yougui 2177.2 a64.2 ab9.5 a0.282 6 a
Guishen 2148.0 bc56.2 bc8.0 bcd0.262 0 ab
Yougui 1175.4 a59.1 abc8.4 bc0.256 6 ab
Guishen 1145.2 bc51.7 cd7.4 cd0.251 4 ab
CK139.6 c47.7 d7.2 d0.235 6 b
Different letters in the same column indicate significant differences at the 0.05 level （P<0.05）.
As shown in Table 1， leaf lengths of Yougui 3， Yougui 2， Guishen 3， Yougui 1 and Guishen 2 were， respectively， 64.9， 64.2， 60.5， 59.1 and 56.2 cm， which were significantly longer than the leaf length of the CK of 47.4 cm. With the treatment times increasing， the plant height increased. It also could be seen that the Yougui treatment was better than the Guishen treatment， and the leaf length of Guishen 1 was not significantly different from that of the CK. The leaf width data in Table 1 showed that the leaf width of Yougui 3， Yougui 2， Guishen 3 and Yougui 1 had the leaf widths， respectively， of 9.7， 9.5 ， 8.7 and 8.4 cm， which were significantly wider from that of the CK of 7.2 cm. With the treatment times increasing， the leaf width also increased. It also could be seen that the Yougui treatment was better than the Guishen treatment， and Guishen 2 and Guishen 1 were not significantly different from the CK in leaf width.
The leaf thickness data in Table 1 showed that the leaf thicknesses of Yougui 3， Guishen 3 and Yougui 2 were， respectively， 0.286 4， 0.286 4 and 0.282 6 mm， which were significantly higher than the value of the CK of 0.235 6 mm. With the treatment times increasing， the leaf thickness also increased. It also could be seen that the Yougui treatment was better than the Guishen treatment， and Guishen 2， Yougui 1 and Guishen 1were not significantly different from the CK in leaf thickness.
Effects of the two silicon fertilizers on chlorophyll content and yield of maize and T. truncatus
The chlorophyll data in Table 2 showed that Yougui 3， Yougui 2 and Yougui 1 had the chlorophyll contents， respectively， of 32.4， 30.9 and 27.9 mg/g， which were significantly higher than the value of the CK of 19.4 mg/g. With the treatment times increasing， the chlorophyll content also increased. It also could be seen that the Yougui treatment was better than the Guishen treatment， and the chlorophyll contents of Guishen 3， Guishen 2 and Guishen 1 were not significantly different from that of the CK.
The yield data in Table 2 showed that the yields of Yougui 3， Yougui 2 and Yougui 1 treatments were， respectively， of 61.6， 59.7， 35.6 and 29.8 g， which were significantly higher than the yield of the CK of 8.6 g. With the treatment times increasing， the maize yield of single ear also increased. It also could be seen that the Yougui treatment was better than the Guishen treatment， and the yields of single ear of Guishen 2 and Guishen 1 higher than that of the CK， but the differences were not significant.
Table 2 Effects of the two silicon fertilizers on chlorophyll content and yield of maize and T. truncates
Treatment Chlorophyll∥mg/gYield∥gDeath rate of T. truncatus∥%
Yougui332.4 a61.6 a29.0 a
Guishen320.9 c35.6 b32.0 a
Yougui230.9 ab59.7 a23.0 ab
Guishen219.6 c19.6 cd26.0 ab
Yougui127.9 b29.8 bc18.0 bc
Guishen119.5 c12.5 d19.0 bc CK19.4 c8.6 d10.0 c
Different letters in the same column indicate significant differences at the 0.05 level （P<0.05）.
The death rate data in Table 2 showed that the death rates caused by the maize leaves of Guishen 3， Yougui 3， Guishen 2 and Yougui 2 reached， respectively， 32.0%， 29.0%， 26.0% and 23.0%， which were significantly higher than the death rate in the CK of 10.0%. With the treatment times increasing， the death rate of T. truncatus also increased. It also could be seen that the Yougui treatment was better than the Guishen treatment， and death rates of T. truncatus in Guishen 1 and Yougui 1 treatments were higher than that in the CK， but the differences were not significant.
Zhiru LIU et al. Effects of Two Silicon Fertilizers on Maize Growth and Tetranychus truncatus Ehara
Discussion and Conclusions
After the treatment with the two kinds of silicon fertilizers， the growth of plant height， leaf length， leaf width and leaf thickness of maize was promoted， but different silicon fertilizers differed in the promoting effect. Yougui has a better effect than Guishen， and to produce the desired effect， it is necessary to spray the fertilizer for 2-3 times.
After the treatment with the two kinds of silicon fertilizers， the chlorophyll content in maize leaves could be improved， and the Yougui treatment exhibited a chlorophyll content significantly higher than that of the CK， while Guishen had no remarkably effect. It could be seen that Yougui has a better effect on the chlorophyll content in maize leaves than Guishen.
After the treatment with the two kinds of silicon fertilizers， the yield of the yield of single ear was improved， and generally， the more the treatment times， the more remarkable the improvement on the yield of single ear. The yield was improved the most remarkably by spraying Yougui for 1-3 times， and spraying Guishen for 3 times.
After the treatment with the two kinds of silicon fertilizers， the death rate of T. truncatus was improved， and the effects achieved by spraying Guishen and Yougui for 2-3 times were the most remarkable.
To sum up， spraying the two kinds of silicon fertilizers for 2-3 times could promote the growth of maize and improve maize yield， and also could alleviate the damage caused by T. truncatus. Therefore， this method could be rationally applied in maize production.
References
[1] TANG X， ZHENG Y. Silicon uptake by plants and its effects on pests and diseases resistance[J]. Journal of Yunnan Agricultural University， 2005， 20（4）： 495-499. [2] DU CQ， LIN KH. Research advances of silicon nutrition[J]. Journal of Yunnan Agricultural University， 2002， 17（2）：192-196.
[3] JIANG XL， DING DD， LI SK， et al. Characteristics of silicon nutrient and its effect on agricultural crops[J]. Crops， 2008（5）： 81-82.
[4] XU CX， LIU ZP， LIU YL.The physiological function of silicon in plants[J]. Plant Physiology Communications，2004， 40（6）： 753-757.
[5] WANG MQ. Effect of complete silicon fertilizer on rice yield[J]. Acta Agriculturae Shanghai， 2005， 21（1）： 71-73.
[6] TIAN P， MA LT， PANG HC， et al. Effects of silicon fertilizer on maize and soybean photosynthetic characteristics and yield[J]. Crops， 2015（6）： 136-140.
[7]ZHENG DH， JIN DY.Occurrence and control of Tetranychus truncatus and T. urticae on corns of Yanbian Area[J]. Hubei Agricultural Sciences， 2015， 54（15）： 3668-3670.
[8] ZHANG MS， JIN DY. Potency test for Tetranychus truncates and T. urticae with seven pesticides[J]. Journal of Changjiang Vegetables， 2009（2）： 58-59.
[9] JIN DY， LYU LS， PIAO J， et al. Developmental threshold temperature and drugeffect test of eggs of Tetranychus truncatus and Tetranychus urticae[J]. Journal of Jilin Agricultural University， 2002， 24（6）： 30-35.
[Methods] Yougui and Guishen were selected and sprayed onto maize for 1， 2 and 3 times， forming difference treatments.
[Results] Spraying the two kinds of silicon fertilizers for different times promoted the growth of plant height， leaf length， leaf width and leaf thickness of maize， increased chlorophyll contents in maize leaves and yield of single ear， and also adversely affected T. truncatus （i.e.， increased the death rate of T.truncatus）. The more the treatment times of silicon fertilizer， the more remarkable the effect， and the higher the adverse effect on T. truncatus.
[Conclusions] In production， spraying silicon fertilizer onto maize for 2-3 times could realize the purposes of increasing maize yield and alleviating the damage by T. truncatus.
Key words Silicon fertilizer； Maize； Growth； Tetranychus truncatus Ehara
Received： December 1， 2017 Accepted： January 5， 2018
Supported by College Students Innovation and Enterpreneurship Traning Program of Yanbian University （ydbksky2017507）.
Zhiru LIU （1966-）， male， P. R. China， bachelor ， major： environmental sciences.
*Corresponding author. Email： [email protected]
There is abundant silicon in the earths crust， and plants growing in soil contain different amounts of silicon[1]. As silicon exists widely and shows no remarkably insufficiency symptoms， the effect of silicon on plant growth does not attract peoples attention. With the continuous increase of plant physiological experiments， the importance of silicon in plant life is proved[2]. Silicon as a useful element for plants， could significantly promote the healthy growth of crops， and is proved to be a necessary element to eggplant and cucumber[3]. Silicon nutrient alleviates heavy metal toxicity and salt stress through the improvement of the structure of plant leaf. It not only improves the drought resistance and diseases resistance in plants， but also improvesthe resistance to pests in plants， thereby reducing the damage to crops by pests， and therefore， the economic output and quality agricultural quality are improved[4-5]. However， there were few studies on the effect of silicon fertilizer on the photosynthesis of maize[6].
Maize is a main upland crop planted in the Northeast China and North China. However， in recent years， maize is suffered from Ostrinia nubilalis， armyworm and spider mite， and especially from the end of last century， continuous drought happens in the north areas， Tetranychus truncatus Ehara occurs in the maizegrowing areas in the northern China continuously[7]. The damage to agricultural crops become more and more serious， and the loss rate caused by the damage reached 10%-30%， and the control of the pest has become an urgent affair[8-9]. For this， the effects of silicon fertilizer on maize growth and the occurrence of T. truncatus were discussed， so as to serve the production. Materials and Methods
Experimental materials
Silicon fertilizers
Yougui was produced by Nangong Huayang Chemical Plant， and Guishen was produced by Cheng Pu Fertilizer Industry.
Tested maize
The maize variety C was provided by professor Zheng from Genetic Breeding Laboratory， Agricultural College， Yanbian University.
Tested pests
T. truncatus was collected from the leaves of weeds in the greenhouse of Agricultural College， Yanbian University. The pests were fed and propagated on cowpea in laboratory. The pests were cultured at 23-27 ℃ under 16 （light） L∶8 （dark） D and a relative humidity of 50%-60%.
Experimental instruments
Electrodyne （3JWB16A）； plant chlorophyll meter （SYS02）； leaf thickness measuring instrument （LS3）； electronic scale （JMA2003）.
Experimental methods
Sowing of maize
On June 5， the field with poor fertility in the Agricultural College was turned over and ridged， and each hole was sown with 2 seeds according to a row placing of 60 cm and a plant spacing of 60 cm. On July 5， only one healthy plants was reserved in one hole.
Silicon fertilizer treatments
Each plot included 2 rows， each of which included 10 plants， and there were 20 maize plants in one plot. From July 20， silicon fertilizer treatment was performed every 10 d. Yougui and Guishen were diluted by 750 times， and sprayed with fertilizer onto the leaves with the electrodyne. In order to achieve well adsorption of the silicon fertilizers onto maize leaves， 2 000 times dilution of Tween 80 was added into the electrodyne. The experiment was designed with seven treatments， i.e.， control （CK）， Yougui1 （spraying Yougui once， similarly hereinafter）， Yougui 2 and Yougui 3， and Guishen 1， Guishen 2 and Guishen 3.
Investigation of maize growth
Plant height， leaf length and leaf width measurement
On September 2， the plant height of maize was measured with a measuring scale and recorded. During the measurement of leaf length and leaf width of maize， the leaf of ear was selected and measured， and the values were recorded.
Measurement of chlorophyll content and leaf thickness of maize
On August 20， the chlorophyll content and thickness of the leaf of ear were measured with the chlorophyll meter and the measuring instrument of leaf thickness， respectively. During the determination of chlorophyll， the measurement was performed at the same time period. During the measurement of leaf thickness， the same measurement position was selected when keeping away from leaf veins. Yield investigation of single ear of maize
Each ear was collected， and the grains were stripped off and added into a paper bag which was labeled. The grains were weighed one month later， and the values were recorded.
Investigation of T. truncatus
On August 15， a layer of sponge with a thickness of 1 cm was placed in a culture dish with a diameter of 12 cm， and a layer of degreasing cotton with a thickness of 1 mm was laid on the sponge. Water was added into the culture dish to the level of the sponge. Leaves were collected from the 7 treatments （CK， Yougui1， 2 and 3 and Guishen1， 2 and 3）， respectively. Leaf segments （2 cm×5 cm） were cut and placed on the degreasing cotton with the leaf back upward， and no spacing was reserved between the leaf segments and degreasing cotton. Onto each leaf segment， 10 pests were put with a fine brush. Into each culture dish， 3 leaf segments were placed at intervals between each other， as three replicates. Watering was performed on the 1st d and the 3rd d， and the death rate of T. truncatus was investigated and recorded on the 5th d.
Analysis software
The data were analyzed with DPS v7.05， and multiple comparisons were performed by Duncans new multiple range method.
Results and Analysis
Effects of the two silicon fertilizers on maize growth
It could be seen from Table 1 that Yougui 3， Yougui 2， Yougui 1 and Guishen 3 had the plant heights， respectively， of 182.0， 177.2， 175.4 and 157.0 cm， which were significantly higher than the plant height of the CK of 136.6 cm. With the treatment times increasing， the plant height also increased. It also could be seen that the Yougui treatment was better than the Guishen treatment， and the plant heights of Guishen 2 and Guishen 1 were not significantly different from that of the CK.
Table 1 Effects of the two silicon fertilizers on plant height， leaf length， leaf width and leaf thickness of maize
Treatment Plant height∥cmLeaf length∥cmLeaf width∥cmLeaf thickness∥mm
Yougui 3182.0 a64.9 a9.7 a0.286 4 a
Guishen 3157.0 b60.5 ab8.7 ab0.286 4 a
Yougui 2177.2 a64.2 ab9.5 a0.282 6 a
Guishen 2148.0 bc56.2 bc8.0 bcd0.262 0 ab
Yougui 1175.4 a59.1 abc8.4 bc0.256 6 ab
Guishen 1145.2 bc51.7 cd7.4 cd0.251 4 ab
CK139.6 c47.7 d7.2 d0.235 6 b
Different letters in the same column indicate significant differences at the 0.05 level （P<0.05）.
As shown in Table 1， leaf lengths of Yougui 3， Yougui 2， Guishen 3， Yougui 1 and Guishen 2 were， respectively， 64.9， 64.2， 60.5， 59.1 and 56.2 cm， which were significantly longer than the leaf length of the CK of 47.4 cm. With the treatment times increasing， the plant height increased. It also could be seen that the Yougui treatment was better than the Guishen treatment， and the leaf length of Guishen 1 was not significantly different from that of the CK. The leaf width data in Table 1 showed that the leaf width of Yougui 3， Yougui 2， Guishen 3 and Yougui 1 had the leaf widths， respectively， of 9.7， 9.5 ， 8.7 and 8.4 cm， which were significantly wider from that of the CK of 7.2 cm. With the treatment times increasing， the leaf width also increased. It also could be seen that the Yougui treatment was better than the Guishen treatment， and Guishen 2 and Guishen 1 were not significantly different from the CK in leaf width.
The leaf thickness data in Table 1 showed that the leaf thicknesses of Yougui 3， Guishen 3 and Yougui 2 were， respectively， 0.286 4， 0.286 4 and 0.282 6 mm， which were significantly higher than the value of the CK of 0.235 6 mm. With the treatment times increasing， the leaf thickness also increased. It also could be seen that the Yougui treatment was better than the Guishen treatment， and Guishen 2， Yougui 1 and Guishen 1were not significantly different from the CK in leaf thickness.
Effects of the two silicon fertilizers on chlorophyll content and yield of maize and T. truncatus
The chlorophyll data in Table 2 showed that Yougui 3， Yougui 2 and Yougui 1 had the chlorophyll contents， respectively， of 32.4， 30.9 and 27.9 mg/g， which were significantly higher than the value of the CK of 19.4 mg/g. With the treatment times increasing， the chlorophyll content also increased. It also could be seen that the Yougui treatment was better than the Guishen treatment， and the chlorophyll contents of Guishen 3， Guishen 2 and Guishen 1 were not significantly different from that of the CK.
The yield data in Table 2 showed that the yields of Yougui 3， Yougui 2 and Yougui 1 treatments were， respectively， of 61.6， 59.7， 35.6 and 29.8 g， which were significantly higher than the yield of the CK of 8.6 g. With the treatment times increasing， the maize yield of single ear also increased. It also could be seen that the Yougui treatment was better than the Guishen treatment， and the yields of single ear of Guishen 2 and Guishen 1 higher than that of the CK， but the differences were not significant.
Table 2 Effects of the two silicon fertilizers on chlorophyll content and yield of maize and T. truncates
Treatment Chlorophyll∥mg/gYield∥gDeath rate of T. truncatus∥%
Yougui332.4 a61.6 a29.0 a
Guishen320.9 c35.6 b32.0 a
Yougui230.9 ab59.7 a23.0 ab
Guishen219.6 c19.6 cd26.0 ab
Yougui127.9 b29.8 bc18.0 bc
Guishen119.5 c12.5 d19.0 bc CK19.4 c8.6 d10.0 c
Different letters in the same column indicate significant differences at the 0.05 level （P<0.05）.
The death rate data in Table 2 showed that the death rates caused by the maize leaves of Guishen 3， Yougui 3， Guishen 2 and Yougui 2 reached， respectively， 32.0%， 29.0%， 26.0% and 23.0%， which were significantly higher than the death rate in the CK of 10.0%. With the treatment times increasing， the death rate of T. truncatus also increased. It also could be seen that the Yougui treatment was better than the Guishen treatment， and death rates of T. truncatus in Guishen 1 and Yougui 1 treatments were higher than that in the CK， but the differences were not significant.
Zhiru LIU et al. Effects of Two Silicon Fertilizers on Maize Growth and Tetranychus truncatus Ehara
Discussion and Conclusions
After the treatment with the two kinds of silicon fertilizers， the growth of plant height， leaf length， leaf width and leaf thickness of maize was promoted， but different silicon fertilizers differed in the promoting effect. Yougui has a better effect than Guishen， and to produce the desired effect， it is necessary to spray the fertilizer for 2-3 times.
After the treatment with the two kinds of silicon fertilizers， the chlorophyll content in maize leaves could be improved， and the Yougui treatment exhibited a chlorophyll content significantly higher than that of the CK， while Guishen had no remarkably effect. It could be seen that Yougui has a better effect on the chlorophyll content in maize leaves than Guishen.
After the treatment with the two kinds of silicon fertilizers， the yield of the yield of single ear was improved， and generally， the more the treatment times， the more remarkable the improvement on the yield of single ear. The yield was improved the most remarkably by spraying Yougui for 1-3 times， and spraying Guishen for 3 times.
After the treatment with the two kinds of silicon fertilizers， the death rate of T. truncatus was improved， and the effects achieved by spraying Guishen and Yougui for 2-3 times were the most remarkable.
To sum up， spraying the two kinds of silicon fertilizers for 2-3 times could promote the growth of maize and improve maize yield， and also could alleviate the damage caused by T. truncatus. Therefore， this method could be rationally applied in maize production.
References
[1] TANG X， ZHENG Y. Silicon uptake by plants and its effects on pests and diseases resistance[J]. Journal of Yunnan Agricultural University， 2005， 20（4）： 495-499. [2] DU CQ， LIN KH. Research advances of silicon nutrition[J]. Journal of Yunnan Agricultural University， 2002， 17（2）：192-196.
[3] JIANG XL， DING DD， LI SK， et al. Characteristics of silicon nutrient and its effect on agricultural crops[J]. Crops， 2008（5）： 81-82.
[4] XU CX， LIU ZP， LIU YL.The physiological function of silicon in plants[J]. Plant Physiology Communications，2004， 40（6）： 753-757.
[5] WANG MQ. Effect of complete silicon fertilizer on rice yield[J]. Acta Agriculturae Shanghai， 2005， 21（1）： 71-73.
[6] TIAN P， MA LT， PANG HC， et al. Effects of silicon fertilizer on maize and soybean photosynthetic characteristics and yield[J]. Crops， 2015（6）： 136-140.
[7]ZHENG DH， JIN DY.Occurrence and control of Tetranychus truncatus and T. urticae on corns of Yanbian Area[J]. Hubei Agricultural Sciences， 2015， 54（15）： 3668-3670.
[8] ZHANG MS， JIN DY. Potency test for Tetranychus truncates and T. urticae with seven pesticides[J]. Journal of Changjiang Vegetables， 2009（2）： 58-59.
[9] JIN DY， LYU LS， PIAO J， et al. Developmental threshold temperature and drugeffect test of eggs of Tetranychus truncatus and Tetranychus urticae[J]. Journal of Jilin Agricultural University， 2002， 24（6）： 30-35.