Effect of Planting Density，F(xiàn)ertilizer Level，and Number of Seedlings per Hole on Yield of Coix Lachryrma-jobi L．

Zhiqin SONG ，M aohong AO，Gang SHEN，Pengfei LIU

1．Guizhou Institute of Modern Chinese Medicinal Materials，Guiyang 550006，China；2．Guizhou Subtropical Crop Institute，Guizhou 562400，China

1 Introduction

Coix Lachryrma-jobi L．is an annual or perennial Gramineae C4 herb plant．Its common names include coix seed，Job's tears（Australia），adlay（Philippines），sila（Fiji），and ma yuen（China）［1］．It is an important medicinal and edible plant resource．Asmedicinal material，Coix Lachryrma-jobi L．has sweet，bland，and slightly cold properties．It has functions of inducing diuresis for removing edema，invigorating the spleen and dispelling dampness，and clearing heat and discharging pus．As edible material，Coix Lachryrma-jobi L．contains higher calorie than rice and wheat，and it is rich in fat，variety of amino acids，and vitamin B1，vitamin B2，Ca，P，Mg，K，has high nutritive value，and can be rated as king of Gramineae crops［2］．Guizhou Qianxinan Buyei and Miao Autonomous Prefecture is the major area of planting Coix Lachryrma-jobi L．The planting area remains in 300000 mu approximately．Coix Lachryrma-jobi L．is the major characteristic cash crop in local area．In order to study high yield cultivation technology for Coix Lachryrma-jobi L．，and discuss the effect of planting density，fertilizer level，and number of seedlings per hole on yield of Coix Lachryrma-jobi L．，and select optimum combination of these factors，and guide production and planting，we took domesticated variety Xingren Small White Shell of Coix Lachryrma-jobi L．a(chǎn)s an example．Using L9（34）orthogonal design，we studied the effect of planting density，fertilizer level，and number of seedlings per hole on yield of Coix Lachryrma-jobi L．It is expected to provide reference for high yield cultivation technology of Coix Lachryrma-jobi L．

2 Materials and methods

2．1 General information of experimental siteThe experimental site is situated in Tuanpo Village in Xingren County of southwest Guizhou and the geographical position is E105°23．266′，N25°22．687，the altitude is 1260 m．It is dry slope land，sandy soil，fertility is moderate．The Coix Lachryrma-jobi L．land is continuous cropping land．

2．2 Experimental materialsWe took domesticated variety Xingren Small White Shell of Coix Lachryrma-jobi L．planted in southwest Guizhou as experimental material．

2．3 Experimental methods

2．3．1 Experiment design．The experiment adopted L9（34）orthogonal design．Experimental factors are planting density（A），fertilizer level（B），number of seedlings per hole（C），and each factor is arranged at three levels［3］．Namely，A1，A2，and A3；B1，B2，and B3；C1，C2，and C3．For spacing in the rows x row spacing，A1is40 cm x 40 cm，A2is40 cm x60 cm，and A3is40 cm x 80 cm．B1is 25 kg pure nitrogen，25 kg pure phosphorus，and 25 kg pure potassium（calculated at 667 m2，the same below）；B2 is 20 kg pure nitrogen，20 kg pure phosphorus，and 20 kg pure potassium；B3is 15 kg pure nitrogen，15 kg pure phosphorus，and 15 kg pure potassium．C1is3 seedlings per hole，C2is5 seedlings per hole，and C3is7 seedlings per hole．The above three factors at three levels form 9 orthogonal processing．According to L9（34）orthogonal layout design（as listed in Table 1），each processes3 repetitions，obtaining a total of27 plots，randomly distributed with area of 24m2．

2．3．2 Experiment method．Using direct seeding technology，we sowed in the manner of bunch planting in the middle of April．When 2－3 leaves appear，we thinned out excessive seedlings according to experiment design，and each hole keeps different number of seedlings．In accordance with fertilizer demand of Coix Lachryrma-jobi L．，fertilizer was applied in 4 times［4］：base manure accounts for 30%of total fertilizer，the first time fertilizer application（when 4－5 leaves appear）accounts for 20%of total fertilizer，the second time fertilizer application（at the jointing stage）accounts for40%of total fertilizer，the third time fertilizer application（in the flowering period）accounts for 10%of total fertilizer．In the breeding period，it is required to pay attention to field management and prevention and control of plant diseases and insect pests．It is required to strengthen record of field observation，and make record of period of emergence，period of heading，period of flowering，and mature period of processing plots．In the mature period，we randomly sampled 10 holes in experiment plots to test seeds，and make record of tillering rate，plant height，number of ears per hole，number of grains per ear，and weight of thousand grains．

Table 1 Design of L9（34）orthogonal layout

2．3．3 Data analysis．Wemade variance analysis using DPSdata processing software．

3 Results and analyses

3．1 Variance analysis of orthogonal experiment［5］Yield of combination of orthogonal experiment with different planting density，fertilizer level and number of seedlings is listed in Table 2．From the extreme difference in Table2，it indicates that the action of effect of factors on the yield is A＞C＞B，namely planting density＞number of seedlings per hole＞fertilizer level．Through variance analysis in Table 3，we know that there is significant difference（P＜0．05）in the effect of factor A，namely，the planting density，on the yield；there is no significant difference in the effect of factor B and C on the yield，showing the dominant factor influencing the yield of Coix Lachryrma-jobi L．is planting density．Combining the extreme difference analysis in Table 2，it is known that the optimum combination of planting is A3B3C2，namely，the planting density is40 cm x 80 cm，the fertilizer level is pure nitrogen 15 kg，pure phosphorus 15 kg，and pure potassium 15 kg，and the number of seedlings per hole is 5．

Table 2 Yield of combination of orthogonal experiment with different planting density，fertilizer level and number of seedlings

Table3 Variance analysis of combination of orthogonal experiment with different planting density，fertilizer level and number of seedlings

3．2 The effect of planting density on economic properties of Coix Lachryrma-jobi L． In the condition of different planting density，taking5 seedlings per hole as plot of seed test，we selected 10 holes to make random seed test，the test results are listed in Table 4．From Table 4，we can see that with constant decrease of planting density，although the number of seedlings permu is reduced，the tillering rate，number of ears per hole，and number of grains per ear have increase．Therefore，in the planting process of Coix Lachryrma-jobi L，it is required to properly reduce the planting density．Lower planting density will bring better ventilation and sunshine penetration，higher tillering rate，and more effective number of ears，side branches and grains，so as to significantly increase the yield of Coix Lachryrma-jobi L．

4 Discussions and conclusions

From this experiment，it can be concluded that planting density has significant effect on the yield of Coix Lachryrma-jobi L，while the effect of fertilizer level and number of seedlings per hole is no significant on the yield of Coix Lachryrma-jobi L．This indicates that in the planting of Coix Lachryrma-jobi L，planting density is a major factor influencing yield of Coix Lachryrma-jobi L．In the actual planting，it is recommended to select appropriate planting density to ensure high yield of Coix Lachryrma-jobi L．The plant height of Coix Lachryrma-jobi L is as high as 1．5－2．0 m，mutual shading situation is serious．With increase of planting density，the tillering rate，number of grains per plant and weight of thousand grains decrease．Therefore，properly sparse planting is favorable for increasing high yield of Coix Lachryrma-jobi L．Besides，the planting density is mutually influenced with the basic number of seedlings［6］．When the planting density increases，although the tillering rate，number of ears per hole，and number of grains per ear decrease，since the basic number of seedlings is high，it still can realize high yield．Therefore，in the planting of Coix Lachryrma-jobi L，it is recommended to coordinate the relationship between planting density and basic number of seedlings and select an appropriate planting density and basic number of seedlings to ensure high yield of Coix Lachryrma-jobi L．

［1］PANG XF，ZHANG SW，QU ZC，et al．The growth characteristics and high－yield culture technique of Coix L．［J］．Shandong Agricultural Sciences，1996，28（3）：15－17．（in Chinese）．

［2］CAIZX，LIU HJ，XIEWJ，et al．Research advances in Coix L．biology［J］．Crops，2013，16（2）：17－18．（in Chinese）．

［3］ZHAOYJ，LIU ZH．Study on the planting density ofCoix L．［J］．Jorunalof Chinese Medicinal Materials，1992，15（12）：11－13．（in Chinese）．

［4］LIN YZ．Effects of different planting densities and fertilizer supplies on yield and its components in coix（Coix Lachryrma-jobi L．）［J］．Chinese Agricultural Science Bulletin，2008，24（6）：217－221．（in Chinese）．

［5］TANGQY，F(xiàn)ENGMG．Practical statistic analysis and its computer processing platform［M］．Beijing：China Agriculture Press，1997：77—90．（in Chinese）．

［6］LINWQ，MEIXQ，SUWJ，et al．Studies on the cultural technique of later－ripening jobstears（Coix lacryma-jobi）for its high－yielding［J］．Journal of Zhejiang Agricultural Sciences，2002（2）：57－59．（in Chinese）．