Comparative Analysis Of Yield-related Traits And Their Influencing Factors Of Oil Palm Introduced In Different Regions Of Guangdong

The shortage of edible oils in China due to serious competition between grain and oil crops for arable land has led to the import of huge volumes of vegetable fats,of which about 6 million tons of palm oil has to be imported annually by China.Oil palm(Elaeis guineensis Jacq.),known as the king of the edible oils in the world,is the tropical oil crop with the largest production and the higest yield per unit in the word,and it is slso one of important woody oil crops in the tropic of China in the future.However,oil palm is a typical tropical plant,but the tropical area is located at the north fringe of tropics in China,where nature disasters such as wind,cold,drought and others occurs occasionally.In order to develop a series of cultivation techniques of oil palm in northern tropical environments in China,38 elite individual plants from the oil palm populations of 6 representative regions in Guangdong,i.e.Dongguan,Maoming,Shenzhen,Huazhou,Zhanjiang and Leizhou,were selected for observation in the next 5 years,which based on the results of the survey of oil palm germplasm resources introduced in Guangdong.Oil palm EST-SSR molecular markers were developed to identify the similarities of these 38 individuals through analysis of genetic diversity and genetic relationships.Some analysis methods,i.e.analysis of variance,phenotypic correlation analysis and path analysis,were employed to compare the yield-related traits such as vegetative growth,yield components,cold resistance and leaf anatomical structure features in the individuals and populations of the selected oil palm and the yield contribution traits such as climatic conditions and soil properties in different regions to analyze the major factors affecting yield and cold resistance of oil palm.The results would provide theoretical basis and technical support for the utilization of the preselected individual elite plants of oil palm.The main results are as follows:1.The comparison and correlation analysis of leaf anatomical features,EST-SSR genetic diversity and the genetic relationship showed that 38 palms introduced in 6 regions of Guangdong had a high homology among them and was not regionally clustered according to the results of the cluster analysis,which was consistent to the results of survey of oil palm introduced in Guangdong.2.The electrical conductivity method in associated with the Logistic equation was used to evaluate the cold resistance of oil palm to select the cold tolerant individuals and populations.The semi-lethal temperature was used as the identification index for cold resistance to compare and analyze the differences of cold tolerance in individuals and populations,and the correlation of cold tolerance with the vegetative growth and yield component traits.The results are given as follows.(1)There were highly significant differences in cold tolerance between the individuals and the populations.and a cold-tolerant individual SZ7(-6.19℃)from Shenzhen population and a cold-tolerant population(-5.44℃)from Dongguan were selected.(2)The cold resistance of the individuals and populations showed a significantly negative correlation with the bunch weight.3.Some traits such as the normal fruit number and bunch weight,were the important indexes for the evaluation on vegetative growth and yield of oil palm.Eighteen growth and yield component traits from a total of 38 individuals of oil palm in 6 populations were observed in the field for 5 years in a row,and the observations were given as follows.(1)All traits were significantly different in individuals,patial traits had significant regional and annual differences.(2)Normal fruit weight(ANFW)and bunch weight(ABW)had highly significant correlation with and the highest positive direct effects on NFF and FFB,respectively,and were yield determinant factors for oil palm individuals,based on which a high-yielding individual MM3(44.33kg/plant/year)with NFF and MM5(115.44kg/plant/year)with FFB were selected.This was consistent with the analysis of variance.(3)Average normal fruit number(ANNF)and aborted bunch ratio(ABR)were yield determinant factors for oil palm populations.ANNF had significant positive relationship with and the highest positive direct effects on NFF,and ABR had significant negative relationship with and the highest negative direct effects on FFB,based on which populations with high NFF(20.50kg/plant/year)and with high FFB(61.38kg/plant/year)was selected from Huazhou.The selection of populations by using the NFF was consistent with the analysis of variance.4.Meteorological factors,such as effective accumulated temperature,were the important factors influencing on vegetative growth and yield component traits of oil palm.Climatic data of 16 years with 6 climatic parameters for the 6 regions were collected to compare and analyze the influences on vegetative growth and yield component traits of oil palm.The results showed that annual effective accumulated temperature above 10℃(MAAT)was the major factor affecting the number of bunch(NB),yield of normal fresh fruit(NFF),annual number of fruit(ANF),annual number of normal fruit(ANNF)and ratio of fruit weight to bunch weight(F/B),which showed that the higher MAAT increased the NB,ANF,ANNF and F/B and and hence the NFF.The MAT had a decisive influence on frond production(FP)and fruit compaction rate(FCR),while other climatic parameters gave an indirect effect on FP and FCR through the MAT pathway,indicating that MAT improved the FCR but inhibited the FP.The annual mean temperature(MAT)had a decisive influence on the frond production(FP)and fruit compaction rate(FCR),while other climatic parameters gave an indirect effect on FP and FCR the MAT pathway,indicating that MAT improved the FCR but inhibited the FP.The annual minimum temperature(EMT)was the main factor influencing sex ratio(SR)and was closely correlated with the SR.The high EMT improved the proportion of female inflorescences.The annual temperature of the coldest month(ATCM)was the main influencing factor on the ratio of female inflorescence abortion with the highest direct influence.The annual sunshine duration(ASH)was significantly correlated with the aborted bunch ratio(ABR),total number of inflorescences and bunches(NIB),average bunch weight(ABW)and yield of fresh fruit bunch(FFB),and was hence their determinant factor.This showed that the higher ASH increased ABR and reduced NIB and ABW,which led to reduced yield of FFB.The annual rainfall was the decisive factor for the average normal fruit weight with the highest positive direct effect.5.Soil properties,such as the sand content and available potassium,have strong influences on vegetative growth and yield component traits of oil palm.The soil 0-40cm deep in oil palm populations of the 6 regions was collected for 4 years,and 7 soil parameters were determined to compare and analyze their effects on the growth and yield component traits of oil palm.The results were given as follows.Soil sand content was closely correlated with the yield of normal fresh fruit(NFF),single fruit weight(ASFW),normal fruit weight(ANFW),fruit compaction ratio(FCR)and ratio of felale inflorescence abortion(RAFM)and had a decisive impact on them,suggesting that the soil texture,particularly adequate sand content,played an important role in improving the oil palm yield and reducing the ratio of aborted female inflorescence.The available phosphorus had the highest impact on the average bunch weight(ABW)but the available potassium content was just the opposite.Nitrate nitrogen content had a decisive effect on the frond production(FP)and was significantly negatively correlated with FP,indicating that the nitrate nitrogen content in the soil is not conducive to the frond production.The ammonium nitrogen content had the highest impact on the average number of fruit(ANF)and the average number of normal fruit(ANNF),and was significantly positively correlated with ANF and ANNF,indicating that the high ammonium nitrogen content in the soil increased the number of normal fruits.The pH value is the decisive factor for sex ratio(SR)of oilpalm,followed by ammonium nitrogen content.Both the high ammonium nitrogen content and the high pH value in the soil improved the proportion of female inflorescences.The pH value was negatively correlated with ammonium nitrogen content,and both the pH value and the ammonium nitrogen content produced a higher indirect effect on sex ratio through each other,indicating that pH value competed well with the soil ammonium nitrogen content in the regulation of SR.Organic matter content was the decisive factor for the number of bunches(NB)and the aborted bunch ratio(ABR),and was significantly negatively correlated with NB and ABR but had the highest direct impact on the FP,suggesting that soil organic matter content mainly facilitated the vegetative growth not the reproductive growth of the oil palm.6.Some factors such as the effective accumulated temperature,available potassium content,leaf adaxial cuticle thickness,were the main factors influencing the cold resistance of of oil palm.The study analyses the effects of climatic characters,soil properties and leaf anatomical features on the semi-lethal temperature,an evaluation index for cold resistance of oil palm.The results are given as follows.(1)The annual effective accumulated temperature above 10℃ was positively related with LT50 and played a decisive role on the LT50.(2)There was no significant correlation between soil properties and LT50,but available potassium in soil had a decisive effect on the improvement of cold resistance by reducing the LT50,whereas the soil available phosphorus played the opposite role.(3)Leaf anatomical structures were not significantly correlated with LTso,but the thicker adaxial cuticle had a major influence on the improvement of cold resistance of oil palm.7.The study reveals the ecological adaptabilities of oil palm newly introduced in Guangdong and provides some useful references for oil palm production in China.The comprehensive analysis showed that the elite individual plants of the survival oil palm could grow normally and bear fruits in such climatic conditions as annual minimum temperature of 4.63～6.03℃,annual temperature in the coldest month of 14.15～15.15 ℃,annual effective accumulated temperature above 10℃ of 8219.38～8532.03℃,and in sandy loam soil of weak acidity to neutral conditions,and give up to 71.89 kg of fresh fruit bunch yield per plant per year and 20.50 kg of fresh fruit yield per plant per year under the conditions of extensive management.