EVAlUA liON OF PROCEDURES FOR ESTIMATING liON OF PROCEDURES FOR ESTIMATING CITRUS FRUIT YIELD ... Analysis

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  • EVAlUA liON OF PROCEDURES FORESTIMATING CITRUS FRUIT YIELD

    GROUNDPHOTOGRAPHY

    ST A TISTICAL REPORTING SERVICE - U. S. DEPARTMENT OF AGRICULTURE

  • CONTENfS

    Surmnary and ConclusionsBackground .Sample Selection ..Presurvey ProceduresField Procedures ........Fruit C01D1ts

    Expansion of Tenninal CountsAnalysis of Expanded Data

    Time Requirements .........Optimum Allocation ........Comparison of Limb Count EstimatorsGround Photography ....Comparison of Estimating SystemsFruit Size Study .Frui t Droppage StudyRemote Sensing ResearchFruit Quality ResearchRecommendationsAppendix AAppendix B

    ..

    .....................

    Pagev1223678

    101420243033404446474953

    Washington, D. C. 20250

    i

    February 1972

  • Table Page1. Quality control indications of COtDlting accuracy, selected

    citrus blocks, Texas, 1969 growing season .. ! 72. Average fruit and variance components: Equal probability

    expansion, selected citrus blocks, Texas, 1969 growingse ason 10

    3. First-stage mapping: Minutes per tree, selected citrus blocks,Texas, 1969 growing season 12

    4. First-stage mapping: Minutes per primary, selected citrusblocks, Texas, 1969 growing season ..... 12

    S. Second-stage mapping: Minutes per primary, selected citrusblocks, Texas, 1969 growing season . 13

    6. Second-stage mapping: Minutes perterminal, selected citrusblocks, Texas, 1969 growing season ... 13

    7. Fruit cOtDlting: Minutes per tenninal limb, selected citrusblocks, Texas, 1969 growing season ................ 14

    8. Fruit counting: Minutes per fruit, selected citrus blocks,Texas 1969 growing season 14

    9. Optimization results:citrus blocks, Texas,

    Equal probability expansions, selected1969 growing season . 17

    10.

    11.

    12.

    13.

    14.

    15.

    16.

    Average number of primary limbs per tree, selected citrusblocks, Texas, 1969 growing season 18Average number of terminal, limbs per primary, selected citrusblocks, Texas, 1969 growing season ........ 18Calculations of nh for each type of citrus, selected citrusblocks, Texas, 1909 growing season .... 19Average fruit variance components: Double ratio estimator,selected citrus blocks, Texas, 1969 growing season . 21Average fruit variance components: Ratio/cluster estimate,selected citrus blocks, Texas, 1969 growing season . 22Coefficients of variation of estimated average fruit count forthree possible estimators, selected citrus blocks, Texas, 1969gr~lng seasoI:l 24

    Comparison of photo COtDlts, selected citrus blocks, Texas,1968 and 1969 growing seasons ............ 25

    ii

  • Table Page17. Comparison of photo C01D1t regression lines, Valencia oranges,

    selected citrus blocks, Texas, 1969 growing season ....... 2818. Average fruit c01D1ting time per slide and number of slides

    per portion of tree c01D1ted, selected citrus blocks, Texas,1969 growing season 29

    19. Average fruit c01D1ted per slide and mnnber of slides perport~on of tree c01D1ted, selected citrus blocks, Texas, 1969groW1ng season 29

    20. Comparison of various estimators, selected citrus blocks, Texas,1969 growi.ng season 31

    21. Comparison of current and historic estimators, selected citrusblocks, Texas, 1968 growing season ....... 32

    22. Early oranges: Average diameter size, selected citrus blocks,Texas, 1968 and 1969 growing seasons .......... 34

    23. Grapefruit: Average diameter size, selected citrus blocks,Texas, 1968 and 1969 growing seasons ... 35

    24. Valencia oranges: Average diameter, selected citrus blocks,Texas, 1968 and 1969 growing seasons ......... 36

    25.

    26.

    Analysis of variance:citrus blocks, Texas,Analysis of variance:citrus blocks, Texas,

    Circumference, early oranges, selectedAugus t 1, 1969 37

    Circumference, grapefruit, selectedAugtlst 1, 1969 38

    27. Analysis of variance: Circumference, Valencia oranges,selected citrus blocks, Texas, September 1, 1969 39

    28. Early orange droppage, selected citrus blocks, Texas, 1968aIld 1969 growing seasons 41

    29. Grapefruit droppage, selected citrus blocks, Texas, 1968 and1969 growing seasons 42

    30. Valencia orange droppage, selected citrus blocks, Texas, 1968an.d 1969 growing seasons 43

    31. Analysis of variance of early orange droppage, selected citrusblocks, Texas, 1969 growing season ..... 44

    32. Correlations of reasurements of size and fruit C01D1ts, selectedcitrus blocks, Texas, 1969 growing season . 45

    iii

  • Table Page33. Regression of harvest size on August 1 size, selected citrus

    blocks, Texas, 1969 growing season .. 5034. Regression of harvest size on September 1 size, selected

    citrus blocks, Texas, 1969 growing season ..... 5035. Regression of harvest size on October 1 size, selected citrus

    blocks, Texas, 1969 growing season .. 5036. Regression of harvest size on November 1 size, selected citrus

    blocks, Texas, 1969 growing se3Son .............. 5137. Regression of harvest size on December 1 size, selected citrus

    blocks, Texas, 1969 growing season 5138. Regression of harvest size on January I size, selected citrus

    blocks, 1969 growing season 51

    39. Regression of harvest weight on harvest size, selected citrusblocks, Texas, 1969 growing season ................. 51

    40. Regression of harvest size on September 1 size and Augustgrowth, selected citrus blocks, Texas, 1969 growing season 52

    41. Regression of harvest size on October 1 size and Septembergrowth, selected citrus blocks, Texas, 1969 growing season 52

    42. Average fruit per tree and variance components, selected citrusblocks, Texas, 1969 growing season ... 5:;

    Use of trade names in this report is foridentification only and does not constituteendorsement of these products or implydiscrimination against other similar products.

    iv

  • st.Mv1ARY AND CONCLUSIONSColor photography and limb COlUlts can be used to forecast citrus fruit

    production, according to USDA-sponsored research in Texas in 1969-70.Estimates of variances and costs of these and other objective yield procedureswere obtained in a random sample of citrus blocks in the Lower Rio GrandeValley as a followup of preliminary research in 1968. Findings based onfruit size and droppage through the 1969 growing season included thefollowing:

    (1) A sample of 65-85 blocks each of early oranges, Valencia oranges,and grapefruit is sufficient to estimate fruit set early in thegrowing season with a coefficient of variation of 10 percent.OptiJlllUllallocations for cOlUlting fruit on sample limbs are twotrees per block, two primary limbs per tree, and two terminallimbs per primary.

    (2) Correlation of estimated fruit per tree and photo COlUlt washigh for all types of citrus fruit studied. [Relationship ofestimated fruit per tree to fruit COlUlt from photos did notvary significantly among blocks.]

    (3) Time required to identify terminal (COlUlt) limbs was reduced witha newly devised limb selection gauge.

    (4) Seasonal fruit growth patterns differed somewhat from the 1968growing season. Differences in fruit set between the two seasonsaffected average size in some blocks of fruit.

    (5) AmolUlt of fruit droppage did not differ significantly between the1968 and 1969 growing seasons.

    (6) Analyses of fruit samples for quality and expected size distributionat maturity may prove as valuable as information on expected yield.

    v

  • EVALUATION OF PROCEDURES FOR ESTIMATING CITRUS FRUIT YIELDFrui t COtmts, Grotmd Photography, Remote Sensing

    byRichard D. Allen

    Standards and Research DivisionStatistical Reporting Service

    BACKGROUNDIn 1968, the Research and Development Branch, Statistical Reporting

    Service (SRS), U.S. Department of Agriculture (USDA), conducted a study ofgrotmd photography and other objective procedures to forecast yields oforanges and grapefruit in selected groves in the Lower Rio Grande Valley.Texas Citrus Mutual and the Remote Sensing Laboratory, Agricultural ResearchService (ARS), USDA, Weslaco, Texas, cooperated in the study. That researchindicated the feasibility of using a variety of new techniques--includingphotography--to arrive at objective yield estimates. !!

    furing the 1969 growing season, a followup study was made in an attemptto resolve some of the problems raised in the earlier survey and to fUrtherrefine fruit cOtmting procedures. Specific objectives of the project in-cluded the following:

    (1) Improvement of sampling definitions and procedures for objectiveyield surveys.

    (2) Estimation of components of variance for the various sources ofvariation in estimating number of citrus fruit per tree.

    (3) Collection of cost information for various objective yield pro-cedures.

    (4) Evaluation of the use of grotmd photography in a sampling designwith estimates of total fruit rather than actual COtmts.

    (5) Study of ways aerial photography might be used to i~rove esti-mation techniques.

    1/ Estimation based on actual plant or fruit characteristics measured orcounted from randomly selected plots or limbs.

  • The Research and DevelopmentBranch, SRS,was responsible for conductingthe 1969 research study. Field workwas carried out by the R&DBranch, TexasState Statistical Office of SRS, and Texas Citrus Mutual. Financing wasshared by SRS,Texas Citrus M.ttual, and the Texas Departmentof Agriculture.The ARSRemoteSensing Laboratory at Weslaco, Tex., assisted with someportions of the research.

    SAMPLESELECTIOO

    A listing of citrus trees compiledby Texas Citrus M.1tualin the LowerRio GrandeValley was used as the sampling frame. Trees were designated bytype of citrus (early oranges, Valencia oranges, or grapefruit) and age (0-3years, 4-7 years, or 8 years and over)