Feb. 4, 1918 Variability of yields of Fruit Trees and Field Trials 257 



RANGE OF INDIVIDUAIv TREE YIELDS 



The extremes of individual tree productivity are shown in Table I. 

 This indicates a wide range of variation even in oranges, lemons, and 

 apples, which are clonal varieties. The greatest range, however, is in 

 the yield of the seedling walnuts. The variations set forth in this table 

 may seem excessive to workers with annual crops. To those familiar 

 with the variation in tree crops, however, this will be recognized as only 

 the normal variation which occurs in most fruit plantations growing on 

 apparently uniform soil, as mentioned in a previous section. Wide 

 variation in the vigor of the rootstock, as well as variation in soil pro- 



FlG. 6. — Diagram showing the individual tree yield (in pounds) of the Johnathan 



apple orchard. 



Yield per tree (pounds) 



Row. 



Total yield per row 7, 082 8, 070 8, 469 



387 

 187 

 337 

 42s 

 42s 

 100 

 325 



I2S 



375 

 300 



512 



162 



275 

 175 



312 



I2S 



300 

 250 

 350 

 187 



300 

 200 

 250 



187 



112 

 SO 

 187 

 162 



250 

 200 

 112 



437 

 450 

 212 

 437 

 350 

 400 

 450 

 487 

 312 

 375 

 462 

 387 

 400 

 375 

 200 

 175 

 15° 

 300 

 187 

 100 

 200 

 287 

 125 

 100 

 ISO 



550 

 175 

 575 

 400 

 425 

 350 

 337 

 262 

 350 

 312 

 212 

 250 



50 

 362 

 312 

 375 

 250 

 250 

 450 



5° 

 262 

 387 

 337 

 337 

 175 

 200 

 287 

 187 



362 

 400 

 S50 

 450 

 375 

 575 

 375 

 437 

 412 

 250 

 325 



37 

 286 

 387 

 350 

 ISO 

 312 

 250 

 261 

 350 

 375 

 362 

 362 

 337 

 32s 

 375 



SO 

 200 



212 

 350 

 300 

 250 

 52s 



337 

 SCO 

 212 

 550 

 525 

 425 

 537 

 47S 

 187 

 262 

 375 

 1 75 

 7S 

 287 

 375 

 325 

 42s 

 312 

 450 

 32s 

 437 

 87 

 SO 



437 

 100 

 550 

 362 

 375 

 137 

 S50 

 32s 

 450 

 337 

 500 

 300 

 275 

 337 

 337 

 375 

 375 

 300 



87 

 100 

 42s 

 200 

 100 

 300 

 200 

 275 

 ISO 



7S 



8,334 



337 

 500 

 475 

 287 

 437 

 337 

 350 

 475 

 437 

 437 

 437 

 375 

 412 

 437 

 500 

 50 

 450 

 262 

 312 

 275 

 350 

 312 

 225 

 200 

 150 

 275 

 325 

 100 



437 

 375 

 300 

 362 

 375 

 350 

 337 

 300 

 250 

 225 



212 



475 

 300 

 337 

 75 

 100 

 425 

 225 

 375 

 187 

 225 

 150 



125 



287 

 250 



Total 

 yield 

 per 

 row. 



2,747 

 2,324 

 3,161 

 3,048 

 3,387 

 2,348 

 3,236 

 2,561 

 3,324 



2, 223 

 2,087 

 2,559 

 2,935 

 2,150 

 2.S74 

 1,662 

 2,548 

 1. 912 

 2,562 

 2,448 

 1,873 

 2,236 

 1,724 

 1,862 

 1,473 

 1,174 



68. 284 



ductivity, may have been instrumental in causing such a variation in 

 yield. 



Table I. — Range of variability in crop production 0/ fruit and nut trees 

 [Extremes and range expressed as percentages of the mean yields of the respective plantations] 



Kind of fruit. 



Naval oranges (Arlington) . . 

 Naval oranges (Antelope 



Heights) 



Valencia oranges 



Eureka lemons 



Seedling walnuts 



Jonathan apples 



Mean yield. 



Pounds. 

 i37±i-6 



i86±i. 7 

 246 ±4. 3 



270±2. 9 



86±i. 6 

 304 ±5- 6 



Extreme yield. 



Per cent. 

 9. I to 246. 3 



. 4 to 193. 8 

 . I to 188. o 

 . 4 to 180. 3 

 . 4 to 276. I 

 - 3 to 193. 2 



Skewness. 



o. 143 ±0.025 



. 001 ± 

 • 25o± 



•359± 



. 269 ± . 049 



•329± -055 



037 

 053 

 043 



