种植园农学基础4A.ppt

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1、种植园农学基础4A Still waters run deep.流静水深流静水深,人静心深人静心深 Where there is life,there is hope。有生命必有希望。有生命必有希望Structure&Important Part of a Tree for Plantation Crops4.1 Oil palm4.2 Rubber4.3 Cocoa4.1 Oil PalmGrowth&morphology of the oil palm relevant to crop management:-Knowledge of some of the botanical featu

2、res of the oil palm is important for proper agronomic management(i)Roots-The oil palm root distribution in the soil must be considered when selecting fertilizer application strategies-The root system and its distribution is thus important factor affecting fertilizer use efficiency in oil palm-Oil pa

3、lm root system comprises an extensive fibrous and adventitious root system that radiates from the prominent bole(about 0.8m diameter),which extends between 0.4 0.5m into the soil at the base of the trunk The root system of the oil palm-4 categories of roots based on differences in root diameter(a)Pr

4、imary roots-6 10mm diameter-Some descend vertically into the soil to provide anchorage,but most descend at various angles and then bend towards the horizontal to provide a framework supporting secondary,tertiary and quaternary roots(b)Secondary roots-2 4mm diameter-Branch at right angles to the prim

5、ary roots and mostly grow upwards towards the soil surface and then turn to grow horizontally(c)Tertiary roots-0.7 1.2mm diameter,15cm length-Arise at right angles to secondary roots(d)Quaternary roots-0.1 0.3mm diameter,0.5m from the soil surface-Vertical root development maybe constrained by the p

6、resence of a high water-table and poor aeration in clay soils or by impermeable layers in the soil-Most studies have shown that the greatest quantity of roots is found within 30cm of the soil surface-Even in 10 years old oil palms planted in a deep volcanic soil in West Sumatera,where soil condition

7、s were ideal for root development,very few tertiary and quaternary roots were found at a depth that 30cm-The depth of soil allowing root proliferation is an important factor to determine the site yield potential-Shallow and hard soils will limited the root proliferation of oil palm(shallow root syst

8、em)and eventually reduce the yield-Oil palm roots are know to traverse great distance,and primary roots of mature palms up to 21m from the palm base have been reported-Quantitative distribution of tertiary&quaternary roots change with palm age An important consideration when choosing fertilizer plac

9、ement strategies-6 YAP:root distribution mirrors canopy development-10 YAP:majority at a distance of 2.5 5m from palm base-The application of fertilizers and crop residues changes soil fertility in the respective zones of application and thus concentration of feeder roots is often greatest in the so

10、il beneath the weeded circle and the frond piles or where EFB have been applied as a mulch layer(ii)Trunk(stem)-Not formed until the palm is 3 years old-Stem of oil palm is an erect&fairly uniform column&may reach a height of 25 30 mDiagram of the stemStem functions:(i)Providing support for the leav

11、es in the crown(ii)A structural enclosure for the vascular system for nutrient and water transport(iii)Storage of carbohydrates and nutrients(particularly K)-Up to about 12 15 years of age,the stem is covered with leaf bases that remain after frond removal during pruning&harvesting-Thereafter,leaf b

12、ase are sloughed off leaving behind scars that occupy a large portion of the stem surfaceHigh increment:-Stem growth is more rapid from 4 YAP to 15 YAP reaching 0.3 0.6m/year-but decreases to about 0.2 0.4m/year in older palms 15 YAP-Rapid height increment reduces the economic life of the palm as ha

13、rvesting is difficult for tall palms(15m)-Strong inter-palm competition due to close palm spacing in the field results in increased vegetative growth of the stem and reduced yield-Very high planting densities may result in economic losses due to both yield reduction and a reduced lifespan for the pl

14、anting(iii)Leaves(fronds)-Oil palm leaves(or fronds)are produced from a single growing bud or apical meristem(lies in a basin-like depression)in the top of the stem at the center of the crown-Each leaf remains enclosed for about 2 years before developing into a central spear&opens-If the apical meri

15、stem is damaged the palm is functionally dead-Existing leaves may remain green for one time but no new leaves will be produced-Thus,if the apical meristem of a seedling palm has been killed or damaged by disease(e.g.bud rot)or pests(e.g.Oryctes beetle),the palm will not recover and must be replaced-

16、When poisoning palm at replanting or thinning,the aim is to kill the apical meristem as well as existing foliage-Oil palm leaves are 7 8m in lengthRachisPetiole cross section insertion point of first true leafPetioleSpineLinear leafletsTerminal leafletsLeaflet with vestigal laminaeThe oil palm leafP

17、etiole:-1 1.5m in length-Consists of the part of the leaf between the trunk and the insertion point of the first true leaflet-Provided with spiny thorns-Petiole cross-section(width x depth of petiole at point of the first true leaf)is a sensitive and useful indicator for vegetative growthRachis:-5 6

18、m in length-Asymmetrical in cross section with a more strongly curved abaxial surface compared with the adaxial surfaceAB=Abaxial faceAD=Adaxial faceLF=Lateral faceCross section of rachisLeaflets(pinnae)-Inserted in two ranks on either side of the rachis-In contrast to the coconut palm(Cocos nucifer

19、a),the insertion angle of leaflets along the leaf rachis is irregularLF=Lateral faceBS=Basal swellingLR=Lower rank leafletCentral portion of rachis from above,showing irregular leaflet insertion-Each leaf contains about 150 250 leaflets each with a midrib and a lamina-Leaflets are 3 5cm wide at the

20、mid point and 80 120cm in lengthLeave production-Leaf takes about 20 24 months to develop to the first open leaf stage-In commercial oil palm leaves are removed when bunches are harvested or during pruning and the oldest leaves will thus be considerably less than 2 years old-Leaf production may be a

21、s great as 40 leaves/palm/year in very young palm(2 3 YAP),but leaf production rate decreases rapid and stabilizes at 18 24 leaves/year in palm 4 6 years-A properly pruned mature palm has about 40 leaves-Unopened leaves or spears are a good diagnostic indicator of drought stress-Severely drought-str

22、essed palms may show up to 6 unopened leaves following a prolonged period under drought condition(e.g.3 months)Leaves arrangement:-The leaves are arranged in spirals as can be seen on the trunk of the mature palms-The leaves occur in spirals because they have been found formed in bud 1370 apart-Ther

23、e are 8 spirals arranged in rows at an angle to the vertical axisThe arrangement of fronds,showing the 8 spirals which are produced(Right-handed)-On some palms the spirals rise to the right,right-handed-In others they rise to the left,left-handed-It is interesting to note that the direction of spira

24、l ascent is not determined geneticallyA right-handed palmA left-handed palm-Frond 1 is the youngest which is fully expanded,having the leaflets almost at right angles to the rachis-Frond 2 will then be 1370 around the crown from Frond 1-Frond 3 is at the same angular spacing from Frond 2 and so on-F

25、rond immediately above or below each other on the right or left hand spirals is separately by eight intervening fronds-e.g.counting down the spiral which has Frond 1 at its upper and then are Frond 1,9,17,25,33,41,etc.-Similarly on the spiral with Frond 2 are Fronds 10,18,26,34,42,etc.Choosing a Fro

26、nd to sample for annual fertilizer recommendation:-The frond chosen must be sensitive indicator of the nutrient status of the palm-Research has shown that Frond 17 is the most satisfactory for this purposes-For preparation of annual fertilizer programmes,Frond 17 on mature palms is chosen to determi

27、ne the nutrition status of the leaflets-Frond 17 is located by counting from the first fully open frond(Frond 1)in the center of the crown and Frond 17 is on the same spiral of Frond 1Finding Frond 17-In a right-handed palm,the sampler must identify this spiral and follow it down,and slightly to the

28、 left,to find Frond 9.Frond 17 will then be the next below,and slightly to the left,of Frond 9-In the case of a left-handed palm,the same procedure is followed but the Frond 17 lies below and to the right of Frond 9(iv)Inflorescence-An inflorescence primordium or bud is produced in the axil of each

29、leaf at leaf initiation and may develop into a male,female or hermaphrodite inflorescence-However,some may abort at an early stage,so that some leaf axils appear to carry no inflorescencesLength of time required for the development and growth of the inflorescences:-The development and growth of the

30、inflorescence takes some 2 to 3 years-During this period the inflorescence will undergo several phonological stages,namely primordia initiation,sex differentiation,sensitivity to abortion,anthesis and bunch failure,before the final ripen bunch is ready for harvest-The time intervals between the vari

31、ous stages differ for palms of different ages10 months14 months4 months5 monthsYoung palm(6 years)Primordia initiationSex differentiationAbortionAnthesisHarvestTotal:33 months12 months16 months4 months5 monthsYoung palm(6 years and above)Primordia initiationSex differentiationAbortionAnthesisHarvest

32、Total:37 monthsSensitivity of inflorescence to environmental factors:-While many seasonally bearing tree crops require some stress(moisture,temperature,light,etc)to induce flowering and fruit set,the oil palm responds to any extended exposure to stress with a reduction in fruit production,while vege

33、tative growth is little affected-In the process of its development,the inflorescence is sensitive to the environmental factors,esp.at certain critical phonological stages.-During the sex differentiation(forming either male or female inflorescence),the inflorescence is sensitive to moisture stress-In

34、 Malaysia,that occasional periods of abnormally high male inflorescence production appeared about 19 22 months(where the inflorescence was at sex differentiation stages)after a prolonged drought -This indicates that moisture stress depresses female inflorescence formation and hence reduce yield-The

35、next critical phonological stage of the inflorescence in the abortion stage-The rate of floral abortion depended upon the severity of the dry season-When irrigation was applied during the dry season,the abortion rate is reduced-Once past the abortion stage,the inflorescence almost invariably develop

36、s normally to anthesis-Once the inflorescence reaches the anthesis stages,and with adequate pollination,it will develop to mature fruit and generally,weather elements have little or no effect on this fruit expansion stage-However sometime sudden failure of pollination bunches 2 4 months after anthes

37、is may occur(bunch failure)which is usually due to the attack by fungus Marasius palmivorus or severe moisture stress-Other factors effect fruit expansion include inadequate fertilizer input,excessive frond pruning and moderate drought.Interbunch competition-One peculiar feature of oil palm is that

38、it supports many inflorescences at any one time and these inflorescences are at different stages of development such as primordia initiation,sex differentiation,abortion stage,anthesis and fruit expansion and maturity-The fruit expansion will consume a large quality of nutrient and thus will deprive

39、 much nutrient for the development of younger inflorescences(interbunch competition)-Therefore,adequate fertilizers are required to meet the growth of the inflorescence and the expansion of the fruitComposition of inflorescences-Inflorescence is a compound spike or spadix carried out on a stout pedu

40、ncle and enclosed in a woody spathe-The spikelets are arranged in a spiral on a central axis-About a month after the inflorescence emerges above the base of the petiole,the outer spathe splits open-Two to three weeks later,the inner spathe splits,and the flowers,more or less embedded in the spikes,a

41、re exposedFemale inflorescence-The female inflorescence may be has 100 300 spikelets and over 2,000 individual flowers in each female inflorescence Spikelet of female flowers Flower bractMale inflorescence:-The male inflorescence is borne on a long peduncle and consists of long finger-like cylindric

42、al spikelets,each comprising 700 1,200 male flowers-Flowers begin to open from the base of the spikelet Opened male flowersMale inflorescence Male spikelet Composition of male inflorescence Pollination-The oil palm is monoecious(e.g.male and female flowers occur separately but on the same plant),but

43、 male and female flowers mature in a sequence such that the oil palm is obligatorily cross-pollinated-Commercial oil palms are pollinated by the weevil Elaedobius kamerunicus which was first introduced in Southeast Asia in the early 1980s-Insects are lured to male flowers(where they feed and complet

44、e their life cycle)by a strong aniseed scent released when the flowers begin to release pollen at anthesis,which persists for 2 5 days-Female flowers also produce an aniseed scent at anthesis(which last for 36 48 hours)and weevils carrying pollen from male flowers are thus attracted to receptive fem

45、ale flowers on neighboring palms-Before anthesis,the stigma of female flower is closed-At anthesis,the trifid stigma curve outwards.The stigmatic lobes are initially white with the central tissue glandular and sticky,turning pink,light brown and ultimately brown-After fertilization,the stigma turns

46、black,withers and becomes woody(v)Fruits-Fruits range from 2 7cm in length and consist of a thin exocarp or skin,an oily pulp or mesocarp,a hard stony endocarp or shell and an endosperm or kernelThe endocarp(shell)and the kernel constitute the seed-Oil is present in both mesocarp and kernel but palm

47、 oil is obtained from the mesocarp-Individual loose fruit contain about 40%oil compared to bunches,which contain about 25%oil-Thus complete collection of loose fruit at harvest is a cardinal aspect of field managementFruit forms-The oil palm has 3 principal fruit forms:the dura(D),pisifera(P)and ten

48、era(T);which are classifies according to shell thickness and mesocarp content-The shell thickness of the oil palm fruit is controlled by a single geneTypeMesocarpShellShell thickness(mm)%of fruitDura20 6525-452.0 8.0Pisifera-No shellTenera60 904-200.5 4.0The composition of dura,pisifera and tenera f

49、ruits as below:-The 3 fruit forms display the existence of the different combinations of the alternate forms of the shell gene (Sh,sh),which exists in pairs in an individual-When the gene-pair is present in the palms as ShSh(homozygous for Sh),the thick-shelled dura fruit is formed Dura-Thick shell-

50、Thin Mesocarp-Big kernel-Good bunch sizeWhen the genetic constitution of the palm is shsh,the shell-less pisifera fruit form is seenPisifera-No shell-Thick Mesocarp-High oil yield-Abortive bunchesWith an Shsh or heterozygous genetic constitution,the fruit is the thin-shelled tenera form Tenera-Thin