| Alfalfa(Medicago sativa L.)is a forage legume crop,which is named as the king of grazing grasses,and widely grown around the world.It is an important feed source for animals.and also rich in ecological functions,alfalfa has played a great important and uniqe role in the adjusting and optimizing of structure of the agriculture and livestock industry,and promoting the structural reform of agricultural supply front.The price for alfalfa product has soared in recent years due to large demand for importing premium alfalfa product and relatively expensive seeds cost.It would be valuable to check effects of seeding rate and various fall dormancy class varieties,on produce performance,quality,biological characteristics and comprehensive benefits.The study will benefit for a better and acurate management,improve the science and technology level of alfalfa industry,promote the healthy and sustaine development of alfalfa industry,and so lead to improve the science and technology of modern agriculture.The study was carried out in the Scientific & Educational park of Henan Agricultural university.In order to explore the quantity trends,produce performance,branch number,plant height,and quality caused by the seeding rate and alfalfa varieties in 2011-2014,split plot design was adopted with the seeding rate(15.0 kg/hm2,22.5 kg/hm2,30.0kg/hm2)as the main production area,8 different fall dormant classes of alfalfa varieties(Concept,WL-319 HQ,Adrenalin,WL-343 HQ,WL-363 HQ,Icon,WL-525 HQ,WL-903HQ)as subplot.Significance of difference,interaction,correlation and regression analysis was carried out to assess the effects of seeding rate and varieties by modern biometric technology and software.In order to provide an optimal seeding rate and varieties for growing alfalfa as reference,a comprehensive evaluation of this study on overall value of alfalfa,dry matter,nutrition index,production performance,crude protein(CP),acid detergent fiber(ADF),neutral detergent fiber(NDF)and relative feed value(RFV)were analysed.This study would contribute to promote the level of scientific development of alfalfa in Henan and all over China,and maximize ecological and economic benefits to alfalfa industry.Results of this study are shown as follows:Experiment 1: Effects of seeding rate and variety on dynamic change of plantpopulation and production performance in alfalfa1.1 There was no significant difference(P>0.05)between winter survival rate and seeding rate.However,winter survival rates range from 85.53% to 98.24% between varieties.Dormant and semi-dormant alfalfa varieties had higher(P<0.05)winter survival rate than that of non-dormant alfalfa varieties,so dormant and semi-dormant alfalfa varieties should have priority over non-dormant ones when grown in Zhengzhou area and where is similar climate conditions.1.2 Seeding rate in alfalfa had highly significant(P<0.01)influence on the dynamic change of plant number.Plant number had positive correlation with seeding rate,and this trend was quite obvious in the first growing year(2011.10.5-2012.10.6).Overall plant number decreased sharply in the first growing year,then decreased slowly in the following year and come to a flat state in the third growing year.Varieties had no effect(P>0.05)on plant number as time goes by.1.3 Regression analysis results revealed a highly significant relationship(P<0.01)of the dynamic change of plant number and cutting time or growth time,which indicate that we can use cutting time or growth time to predict the plant number of alfalfa,and then to predict the quality and production of alfalfa.Under the condition of different sowing rate,the correlation index of total dry matter yield and plant number of 3 years between-0.909 and -1.026,which approach-1 law of self-thinning.1.4 Seeding rate in alfalfa had no significant influence(P>0.05)on the dry matter,while varieties had slightly impact on dry matter.Fall dormant class and interactions between seeding rate and variety had no significant influences(P>0.05).With increase of cutting frequency,dry matter lowered down accordingly.Highest dry matter was observed in the first cutting and the first three cutting are important.To achieve high production performance,Concept should be taken as No.1 priority when grown in Zhengzhou,followed by WL-525 HQ and WL-903 HQ.1.5 Positive correlation between winter survival rate and plant number was obtained with the increase of seeding rate.However,compared to dry matter,both of the winter survival rate and plant number reversed to negative correlation with higher seeding rate.In conclusion,it is advisable to cultivate semi-fall dormant alfalfa varieties in Henan province,and the density rate should be 22.5 kg/hm2-30.0kg/hm2.In the production practice,we should choose the suitable varieties and seeding rate according to the production purpose.And we also can predict plant number and production of alfalfa according to the cutting time each year.Experiment 2: Effects of seeding rate and variety on branch number,plant height,quality and Correlation of biological charater of alfalfa2.1 Seeding rate had no significant effects on the primary and secondary branch number in alfalfa,and the differences among varieties were also not significant.With the increase in the growing years,the primary and secondary branch number of all varieties had increased trend(2012 < 2013 < 2014).2.2 Average branch number of different varieties had no significant difference between2012 and 2013,but significantly higher(P<0.05)than that of 2014.2.3 Seeding rate and growing years had influences on plant height.With the increase of seeding rate,plant height of most varieties decreased gradually from 15.0 to 30.0 kg/ha.The plant heights of the 8 alfalfa varieties in 2013 were higher than those of 2012 and 2014.2.4 Seeding rate had influence on nutrition of alfalfa.CP,EE and RFV increased with the rise of seeding rate,while NDF and ADF decreased.To harvest premium quality of alfalfa,a higher seeding rate could be considered and alfalfa in the first growing year had the best quality.2.5 Seeding rate had positive correlation with CP(P<0.05)and RFV,and negative correlation with ADF and NDF(P<0.05).Fall dormancy had highly significant positive correlation with plant height,NDF,and ADF(P<0.01),and highly significant negative correlation with CP and RFV(P<0.01).Primary branch number had significant positive correlation with CP and RFV(P<0.05),while had significant negative correlation with NDF and ADF(P<0.01).Therefore,there is no significant effect on the branch number as decreasing seeding rate in alfalfa,but plant height was improved.The quality of alfalfa was improved through higher seeding rate.In order to improve the efficiency on the breeding and introducing new alfalfa varieties,quality could be predicted by index such as winter survival rate,seeding rate,plant height,plant number,cutting frequency and branch number.Experiment 3: Effects of seeding rate and varieties on the decisive index and comprehensive benefits in alfalfa3.1 A model was built to evaluate the decision coefficient of alfalfa:?=0.48*DMY/AVG+0.02*DM/AVG+0.15*CP/AVG+0.02*EE/AVG+0.07*NDF/AVG+0.05*ADF/AVG+0.02*ASH/AVG+0.02*Ca/AVG 0.16*RFV/AVG.3.2 According to the above-mentioned model,the decision coefficient increased first then decreased as the increase of seeding rate(22.5kg/ hm2 >30.0kg/ hm2>15.0kg/ hm2).3.3 Based on average dry matter and nutrition value,Concept was put at No.1 priority,followed by WL-525 HQ and WL-343 HQ.3.4 Based on fall dormancy,there was minor difference between fall dormant classes for the decision coefficient.3.5 Decision coefficient reduced with the increase of cutting frequency in all of the three seeding rates.It was quite obvious in the first five cuttings,the decision coefficient were 1stcutting > 2ndcutting > 3rdcutting > 4thcutting > 5thcutting.3.6 From the net returns perspective,Adrenalin(with 30.0 kg/hm2)had the highest production and quality,followed by Concept(22.5 kg/hm2)and WL-343HQ(22.5 kg/hm2).In conclusion,different strategies should be employed according to different purposes.Adrenalin(30.0 kg/hm2),Concept(22.5 kg/hm2)and WL-343HQ(22.5 kg/hm2)should be preferred if net return is priority;while Concept,WL-525 HQ and WL-903 HQ were favored for higher production. |
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