Introduction
Predicting the harvest of cucumbers and controlling the flow of fruit to the processing plant requires a planting sequence based on known response of the crop to environmental conditions at different parts of the growing season. An accumulated heat unit system developed in North Carolina and modified in western Washington appears to predict harvest with a reasonable degree of accuracy under the environmental conditions in those two areas. However, the number of heat units required to achieve crop maturity differs greatly between the two regions. This lack of agreement may be explained by differences in daylength, light intensity, cultivar, and the daily duration of favorable temperature. Thus, it appears that heat unit models will have to be developed for each growing area.
New determinate, semi-determinate, and "little leaf" types of cucumber are becoming available to the industry. These need to be evaluated under Willamette Valley cultural conditions. These lines might respond differently to nitrogen rates and plant populations than do indeterminate lines; the restricted vine growth of determinate lines may favor both higher plant populations and higher rates of nitrogen. In addition, data on yield and size grade response to fertility and plant populations would be very valuable in the development of a multifactor harvest prediction model. Such a model must include the factors of population, cultivar, fertility, irrigation amount and method, and pollination practices, as well as days from planting or heat unit accumulation.
The objectives of this project were: 1) to obtain the accumulated heat units from planting to harvest for selected commercial plantings in the Willamette Valley and develop a harvest prediction model for cucumbers, based on size grade and dollar value; 2) to compare yields and size grades for three to four harvest dates for selected semi-determinate and determinate lines of machine-harvested cucumbers; and 3) to investigate the effect of nitrogen fertilizer rates and plant populations on representative determinate and semi-determinate types of pickling cucumbers.
Methods
Seed companies were contacted to obtain pickling cucumber lines with a fruit length-to-diameter (L:D) ratio of 2.9 to 3.2 and with disease resistance and other characteristics suitable for production in western Oregon. In 1989, ten lines received were selected for trial based on their L:D ratio. Plots were seeded with a V-belt push planter on June 2. Seeds were counted for each plot to give a target population of 80,000 plants per acre for all lines except 'H-19 Little Leaf.' On the suggestion of the breeder, Dr. T. Morelock, of the University of Arkansas, this line was seeded at 50,000 per acre and half of the plots were thinned to 27,000 per acre.
Plots were four-row beds on 78-inch centers and 50 feet long. Between-row spacing was 16 inches. Six plots of each line were seeded in completely random design, with two replications of three harvest dates. Preparation of the sandy loam soil, fertilization, irrigation, weed control, and pollinators were provided by the grower cooperator according to standard Oregon State University production recommendations. However, the grower inadvertently applied a total of 150 pounds N per acre, rather than the normal 50 to 70 pounds. All plots were machine-harvested with a Wilde mechanical harvester at two to three-day intervals. Harvest of most cultivars began when oversize fruit reached 6 percent of the total. Fruit was mechanically graded at a processor receiving station.
Seed of 10 different cultivars or lines was provided by seed companies for evaluation in 1990. Plot size was established to provide approximately one bin of pickling cucumbers for yield and grade measurement and for fruit quality evaluation by a processor.
Planting dates were June 22 and July 3, 1990. Research plots were four rows, spaced 16 inches apart, with beds on 7-foot centers. Plot lengths were 700 and 875 feet long for the first and second planting, respectively, with sufficient area planted to each variety to allow for up to four harvests. All plots were planted using commercial Stanhay planters set to seed at a rate of 80,000 to 85,000 per acre. Nitrogen rate was 100 pounds per acre.
All plots were machine-harvested at two to four-day intervals using the Wilde harvester, except for 'H-19 Little Leaf,' which was harvested only once. Harvest of the first planting began when most of the varieties reached a mean grade of 2.8 to 2.9, with a range throughout the harvest period running from 2.3 to 3.7 (Table 1). Harvest of the second planting commenced earlier with most of the varieties having a mean grade of 2.5 to 2.6, with a range throughout the harvest period from 2.5 to 3.5. All fruit harvested was graded at the receiving station. Dollar values per acre and per ton were calculated using the machine-harvest cucumber pay scale provided by the processor, with no correction for hauling or grower-owned harvester.
A third trial in 1990 was conducted at the North Willamette Research and Extension Center. The plot area was prepared in the last week of May. Initial seeding was on June 1, following broadcast and incorporation of 700 pounds per acre of a 10N-8.7P-16.7K fertilizer. Following seeding, chloramben and naptalam herbicides were applied at 2.0 and 3.0 pounds per acre, respectively, and incorporated with 0.5 inches of overhead sprinkler-applied water. The lines Peto 10588, 'Castlepik', and 'H-19 Little Leaf,' were seeded with four rows per 80-inch wide bed. Plot length was 45 feet. Each line was seeded at a target population of 70,000 and 100,000 plants per acre (except 35,000 and 70,000 for 'Little Leaf').
Main plots of variety x population x harvest date were in randomized complete block design with four replications. On June 29, these main plots were randomly split into three 15-foot long subplots by the application of either 0, 40, or 80 pounds nitrogen per acre as ammonium nitrate. Resulting total N rates were 70, 110, and 150 pounds per acre. Four hives were placed about 50 feet from the plot border for pollination.
Emergence of the Peto line was extremely poor and that of 'Little Leaf' was acceptable only on about half the plots. As a result, the Peto line and 'Little Leaf' were reseeded on July 12. Treatments and cultural methods were as above, with the additional nitrogen applied on August 10. Emergence of the Peto line was excellent on these plots. Emergence of 'Little Leaf' was acceptable, but much of the stand was lost to a root disease. Consequently, harvest data were taken for 'Castlepik' and 'Little Leaf' from the first planting and for the Peto line from the second planting. In addition, there were four harvests of the Peto line, but only a single harvest of 'Little Leaf,' due to the limited number of plots with acceptable plant stand.
'Castlepik' was harvested on August 1 and 6, 'Little Leaf' on August 9, and the Peto line on August 31 and September 4, 7, and 10. Each plot was harvested once and all fruit were removed to simulate a once-over machine harvest. Fruit was graded into size categories on a portable grader provided by Nalley's Fine Foods, Inc.
Results
1989 Variety Trials.
In 1989, the L:D ratio of most cultivars fell within the desired range of 2.9 to 3.0. Fruit lengths were shorter than normal this season, as evidenced by 'Calypso', which would normally have L:D of 3.0 to 3.1. 'Calypso,' 'Napoleon,' and 'HMX4490' showed greater stability in L:D ratio over the course of three harvests than did the other lines (Tables 1 and 2).
A 10:40:40:10 percent grade distribution of grade 1:grade 2:grade 3:grade 4 (0 to 1-inch:1 to 1.5-inch:1.5 to 2-inch:over 2-inch diameter, respectively) is considered a realistic average grade distribution for mechanical harvest. Fruit value for this distribution would be $137.00 per ton based on 1989 processor payment for the different size grades. The three Petoseed lines most nearly produced the desired size distribution commensurate with high yield and dollar return per acre (Table 2). 'H-19 Little Leaf' produced a high return per acre but an unfavorable size distribution. This cultivar does not usually produce a crown set, but rather a heavy secondary set. In these plots, however, crown set occurred on nearly half the plants, making determination of proper harvest period more difficult. This resulted in a high percentage of oversize fruit (grade 4, no value) at harvest.
Yield can be divided into two distinct groups (Table 2). One group of five cultivars produced less than 9,500 pounds paid fruit weight per acre. The other group of five, all determinate or semi-determinate types, yielded more than 9,500 pounds paid weight per acre. The highest yielding lines were 'H-19 Little Leaf,' 'Napoleon,' and PS10588. Dollar return continued to increase with each harvest, while value per ton decreased for most cultivars. Thus, a higher payment for small sizes may be necessary to encourage growers to harvest at a lower mean size grade. Plant population had no effect on yield, mean size grade, or quality of 'Little Leaf.' Data reported for this cultivar are the means of the two populations.
1989 Commercial Plantings.
Data for each commercial planting, harvest date, and delivery for Oregon was provided by a pickle producer. All data are for the cultivar 'Calypso.' Optimum commercial harvest was considered to have an average size grade of 2.5 to 2.6. According to results from Dr. W. C. Anderson for northwest Washington, this should represent an approximate 10:40:40:10 size grade distribution. Mean size grade was calculated for each lot delivered (Table 3). The high degree of correlation between mean size grade and value per ton indicates that mean size grade is a useful estimate of crop value.
The North Carolina accumulated heat unit model (AHU) was tested against days from planting as a predictor of mean size grade and crop value (Table 3). The correlation coefficients suggest that days from planting predicts maturity better than does the AHU model. Even when only harvests with a mean size grade between 2.45 and 2.80 are considered (Table 4), days from planting is the superior predictor of harvest maturity, reflected in the smaller Coefficient of Variation (C.V.) for days from seeding to harvest than for AHU. Other models are also tested, including the AHU plus cold penalty (CP) model developed by Dr. W. C. Anderson. The only model producing a smaller C.V. is Tmean-10-CP. This is in contrast to the results of the North Carolina studies, where models using Tmax were superior to those using Tmean.
Regression analysis was used, where possible, to calculate the probable heat unit accumulation at a mean size grade of 2.5 for several plantings (Table 5). As expected, this provides slightly better agreement in the number of heat units required to reach maturity at different planting dates. Again, only the Tmean-10-CP model is a better predictor than simple days from planting. The relationship between temperature and crop maturity in this study may have been altered by the excessive application of nitrogen and extreme vine growth seen in some of the plantings. These conditions are known to delay maturity. Cucumber growth is influenced by many other factors which may may affect maturity including plant stand, irrigation, pollination, and the environmental factors that affect pollinator performance.
1990 Variety Trials.
Due to unseasonable rains and soil crusting, plant stands were reduced in the 1990 variety trials. Stand counts taken in the second planting indicated estimated plant populations ranging from 43,200 per acre for 'Castlepik' to 89,600 per acre for 'Little Leaf.' Although nitrogen fertilization was reduced to 80 lbs per acre, about one-half the amount applied in 1989, excessive rains, reduced plant populations, and high temperatures combined to produce excessive vine growth again in 1990.
Table 6 provides a summary of yield, size distribution, mean grade, dollar value per acre, and dollar value per ton for four harvests of the eight varieties in the first planting. Mean grade and gross yield generally increased at succeeding harvests, but the greatest return to the grower usually occurred at the first or second harvest. The exception was 'Primepak,' a relatively late-maturing and low-yielding cultivar. For the three varieties with increased return at the second harvest, the mean grade at second harvest averaged 3.18, well in excess of the average grade desired by processors (2.5-2.6). For the four varieties with greatest return at the first harvest, it is not possible to judge from the data whether higher returns would have been generated from an earlier harvest. However, results from the second planting, with harvest starting at grades near 2.5, imply that higher returns would not have been generated by harvesting earlier (Table 8).
The main (average) effects of harvest date and variety for the first planting are given in Table 7. In the first planting, four varieties ('Castlepik,' Peto 50885, 'Calypso' and 'Cross Country') grossed over $600 per acre, when averaged over the four harvests.
Table 8 presents individual data for each cultivar and harvest for the second planting. Maximum gross dollar return per acre for the second planting occurred at a mean grade near 3.2 (when averaged over varieties). In this case, the highest dollar value per acre for all varieties except Peto 50885 occurred at the third harvest. A fourth harvest was not attempted because poor field conditions and rainfall prevented timely harvest, resulting in excessive fruit size.
The first harvest generally occurred at nearly the optimum mean grade from the processor's point of view, but with unacceptably low return to the grower. These results, along with those of the first planting, strongly suggest that the present pay scale actively discourages growers who own their own harvesters from harvesting at the mean grade desired by processors. In any case, it appears that it will be difficult for the Wilde harvester to recover sufficient small fruit to allow a grower to profit when harvesting at a mean grade of 2.5-2.6. Only Peto 50885 exceeded $600 per acre dollar return when averaged over the three harvests (Table 9).
The first harvest of the second planting provided the most realistic distribution for the various size grades at a mean grade desired by the processor (2.5 to 2.6). At this mean grade, yields were from 2.1 to 4.0 tons per acre, with dollars per acre ranging from $294 to $539. These relationships may be heavily influenced by harvester recovery efficiencies as well as crop condition, and environmental factors affecting crop growth and pollination. We can only guess whether greater fruit set per plant with reduced canopy growth might have produced an acceptable yield and dollar return at a mean grade more in line with the processor's product needs.
In contrast to 1989, when the proportion of grade 1 fruit was as high as 19 percent and the average for all varieties at first harvest was 12.6 percent, the proportion of grade 1 fruit in 1990 did not exceed 8 or 6 percent for the first and second plantings, respectively. The desired 10:40:40:10 ratio of size grades was not reached for any variety or harvest. The percentage loss in dollar value per ton over the harvest period is noted for each variety in Tables 7 and 9. This loss in value was least for 'Primepak' and 'Cross Country,' indicating a less rapid change in grade over the harvest period. High-yielding varieties which hold grade over a longer period of time would allow greater flexibility and margin for error in harvesting.
In comparing the commercial plantings harvested by the Byron machine with those harvested by the Wilde, for later planting dates, more accumulated heat units (AHU) are required to reach the same mean grade (Table 10). Inclusion of a cold penalty did not improve the predictive ability of the heat unit model for these plantings. Lowering the maximum cutoff temperature from 90 to around 85 oF might help correct the situation. Obviously, growth and development of 'Calypso' is not a linear function of AHU.
The three growers using the Byron harvester achieved higher gross yield (and dollars per acre) at a mean grade of 2.61 to 2.76 than the grower using the Wilde harvester was able to achieve at a grade of 2.86. Some possible reasons for higher recovered yields for the three growers include: a possible greater efficiency of the Byron harvester, particularly in recovering small fruit; differences in plant stand; or differences in canopy vegetative growth as affected by fertility, irrigation, soil type, and pollination efficiency.
Nitrogen Rate x Population, 1990.
The main effects of plant population, N rate, and harvest date on the yield and size distribution of 'Castlepik' are found in Table 11. Only main effects are shown in all tables since there were no significant interactions affecting any component of yield for any of the three lines.
Plant population per acre had no effect on the size distribution or mean grade of 'Castlepik,' but both gross yield and dollar value per acre were greater at 100,000 than at 70,000 plants per acre. Nitrogen rate had no effect on size distribution at either harvest and did not affect yield or dollar value. Canopy vigor, estimated on a three point scale at mid-season, also was not affected by N rate.
The first harvest of 'Castlepik' occurred at a mean grade of 2.74, with 20 percent oversize. Although at this point the size distribution was already skewed toward larger size grades than would be desired by processors, it is important to note that at the second harvest, with a mean grade of 3.19, dollar return was higher than at the first harvest. This result is consistent with that seen in the second planting of the commercial-scale variety trials (above).
It is also important to note that the size distribution obtained in this trial is probably weighted more heavily toward the smaller sizes than would be the case if the plots were harvested by machine. Our pickers harvested a greater percentage of small fruit than would be recovered by machine. However, a mechanical harvester also tends to drop a portion of oversized fruit that falls from the vine ahead of the pickup device. Also, with a ratio of four hives for only one-half acre of plot area, the high bee population may also have favored greater pollination. We did not make counts of the mean number of fruit recovered per vine, but up to three fruit were observed on many plants. Reduced plant canopy development compared to that observed in the commercial variety trials may also have favored greater visitation by pollinators and greater fruit set per plant.
As with 'Castlepik,' yield and dollar return of 'Little Leaf' were increased at the denser population (Table 12). The percentage of oversized fruit at the single harvest and the mean grade tended to be smaller with the higher plant population, indicating that doubling the plant population may have slightly delayed maturity. Our results, although tentative, indicate that 'Little Leaf' should not be grown at greatly lower populations than other cultivars.
Except for a slight effect on the percentage of nubs and crooks, nitrogen rate did not significantly affect size distribution or yield of 'Little Leaf.' Although not statistically significant, there was a consistent trend toward smaller yield and dollar value per acre with increasing rates of N, while mean grade remained the same.
Plant population per acre had no effect on size distribution of the Peto line 10588 (Table 13). In contrast to the results for 'Castlepik' and 'Little Leaf,' yield and gross value per acre were reduced at the higher population. Increased rates of nitrogen again tended to reduce yield, although the effect was not statistically significant. Harvest of the Peto line commenced when the mean grade was only 1.5 and was continued until the mean grade exceeded 2.8. It is important to note that at a mean grade of 2.8, gross dollar value exceeded that at the preferred mean grade of 2.6 by nearly $300 per acre. The Peto line was by far the greatest yielding line in the trial, with a calculated yield of about 13 tons per acre at a mean grade of 2.6, compared to eight tons for 'Little Leaf' and six tons for 'Castlepik.' However, this comparison is across two planting dates, with generally more favorable weather during growth and development of the Peto line.
In summary, the effect of N was consistent: there appears to be no reason to apply more than 70 pounds N per acre. However, it will be difficult to extrapolate these results to other fields as differences in soil type, organic matter content, tilth, amount of water applied, and other grower cultural practices (e.g. the practice of banding N and P at planting) will affect plant response to nitrogen. The effect of plant populations was not consistent across lines. More work will be needed to determine optimum plant populations for lines with promising yield and processing quality.
Table 1. Effect of planting date on yield and paid weight of ten pickling cucumber varieties, 1989, Marion County, Oregon. Harvest % in grade by weight Wt(lb)/ % Mean Wt. (lb/A) Cultivar date AHU L/D 0-1" 1-1.5" 1.5-2" 2"+ plot ground grade Paid Total $/A $/T August Calypsoz 7 567 2.9 13.7 37.6 41.4 7.3 48 6.6 2.43 5963 6881 447 130 9 598 2.9 10.1 51.7 34.1 4.1 64 9.0 2.31 8241 9431 651 138 11 619 2.9 4.6 44.8 35.6 15.0 87 7.6 2.61 9916 12610 712 112 FancyPak 14 650 2.9 8.4 36.4 47.8 7.3 69 2.2 2.59 8375 9424 559 119 16 670 2.8 2.7 22.7 57.3 17.3 80 3.4 2.91 8710 10995 461 94 18 687 3.2 10.1 39.3 38.2 12.4 64 7.3 2.72 7102 10496 470 90 Flurry 5 543 - 10.1 26.7 53.0 10.3 63 1.5 2.63 7504 8502 485 114 7 567 3.3 5.9 32.6 49.0 12.5 70 3.9 2.69 8174 9942 517 104 9 598 2.8 7.3 34.3 45.0 13.4 109 7.2 2.64 12663 15765 851 108 H-19 LL 16 670 3.0 5.5 20.8 55.4 18.3 118 3.2 2.86 12864 16261 711 87 18 687 2.7 4.6 20.0 49.8 25.6 155 9.0 2.96 15477 22821 873 77 21 721 2.9 2.7 30.0 42.1 25.2 182 14.9 2.90 18224 28683 1128 79 HMX4490 7 567 2.9 13.9 55.5 27.0 3.7 48 2.7 2.22 6104 6620 520 157 9 598 2.8 14.2 47.1 31.4 7.3 40 12.8 2.33 4891 6044 401 133 11 619 2.9 3.5 43.3 40.8 12.3 100 3.5 2.63 11792 13876 795 115 Napoleon 7 567 2.9 9.0 42.7 41.9 6.3 78 4.9 2.45 9782 10931 709 130 9 598 3.0 4.5 32.2 47.3 16.0 122 4.2 2.75 13668 16992 858 101 11 619 3.0 4.1 47.8 41.5 6.6 126 3.4 2.49 15812 17460 1099 126 PS10488 1 567 3.0 15.0 45.0 36.2 3.9 40 9.5 2.29 5159 5927 413 139 2 598 3.0 12.1 40.9 40.5 6.5 83 4.8 2.44 10318 11591 765 132 3 619 3.2 3.7 52.8 37.5 6.0 137 6.0 2.46 17219 19457 1242 128 PS10588 5 567 - 19.2 38.7 39.5 2.6 69 5.0 2.28 8978 9719 718 148 7 598 2.9 10.9 44.6 40.4 4.2 98 5.8 2.38 12596 13953 939 135 9 619 2.8 6.8 37.0 48.4 7.8 132 3.7 2.58 16281 18368 1077 117 PS50885 7 567 3.0 17.8 44.8 36.6 0.8 42 4.8 2.21 5561 5953 455 153 9 598 3.1 11.0 67.8 19.4 1.9 83 4.5 2.12 10854 11581 963 166 11 619 2.9 6.0 54.8 34.9 4.3 119 5.6 2.38 15209 16831 1149 137 Sun 3519 9 598 3.0 13.6 48.5 29.4 8.6 52 5.1 2.34 6365 7350 527 143 11 619 3.0 4.0 54.7 33.6 7.7 87 9.5 2.45 10787 12851 804 125 14 650 2.7 1.8 24.4 60.9 12.8 155 3.9 2.88 17889 21567 914 85 LSD(0.05) NS 7.1 16.7 15.3 9.8 44 6.1 0.33 5021 5800 305 26 zSeed sources: PS lines and 'Little Leaf' from Petoseed; HMX4490 from Harris-Moran; 'Calypso,' 'Flurry,' and 'FancyPak' from Agrow; 'Napoleon' and Sun 3519 from Sun Seeds. 'Little Leaf,' 'Napoleon,' and the three Petoseed lines were semi- determinate to determinate in vine character. Table 2. Main effects of cultivar and planting date on yield and paid weight of pickling cucumbers, 1989, Marion County, Oregon % in grade by wt. Wt(lb)/ % Mean Wt. (lb/A) Treatment AHU L/D 0-1" 1-1.5" 1.5-2" 2"+ plot ground grade Paid Total $/A $/T Cultivar Calypso 595 2.9 9.5 44.7 37.0 9.1 66 7.7 2.45 8040 9641 603 127 FancyPak 673 3.0 7.1 32.8 47.8 12.4 71 4.3 2.65 8062 10304 497 100 Flurry 569 3.0 7.7 31.2 49.0 12.1 81 4.2 2.65 9447 11403 618 109 H-19 LL 693 2.8 4.3 23.6 49.1 23.0 151 9.0 2.91 15522 22588 904 81 HMX4490 595 2.9 10.5 48.6 33.1 7.8 62 6.3 2.38 7596 8846 572 136 Napoleon 595 3.0 5.9 40.9 43.6 9.6 108 4.1 2.57 13087 15128 889 118 PS10488 595 3.0 10.3 46.2 38.1 5.4 87 6.8 2.39 10899 12325 807 133 PS10588 595 2.8 12.3 40.1 42.7 4.9 100 4.8 2.40 12618 14013 911 134 PS50885 595 3.0 11.6 55.8 30.3 2.3 81 5.0 2.23 10541 11455 856 153 Sun 3519 622 2.9 6.5 42.6 41.3 9.7 98 6.2 2.54 11680 13923 748 119 LSD(0.05) NS 4.1 9.6 15.3 5.6 25 NS 0.19 2899 3349 176 15 Harvest 1 586 2.9 12.6 39.7 40.8 6.9 63 4.6 2.42 7665 8757 554 133 2 613 2.9 8.0 41.4 40.3 10.3 88 6.7 2.53 10372 12620 723 120 3 638 2.9 5.1 40.9 42.5 11.6 121 6.3 2.61 14211 17511 944 110 LSD(0.05) NS 2.3 NS NS 3.1 20 NS 0.10 1588 1834 97 8 Table 3. Grade distribution of 'Calypso' cucumber vs. heat unit accumulation (AHU) for several planting and harvest dates, Willamette Valley machine-harvested fields, 1989 Planting Harvest % in grade by weight Mean date date Days AHU 0-1" 1-1.5" 1.5-2" 2"+ grade $/ton June 2 Aug. 10 69 610 7.6 34.8 41.1 16.5 2.67 115.63 June 2 Aug. 11 70 619 3.9 35.7 24.7 34.4 2.91 96.37 June 3 Aug. 12 70 616 3.7 54.4 30.3 9.9 2.47 135.07 June 3 Aug. 13 71 626 1.8 41.9 37.2 18.5 2.73 109.76 June 3 Aug. 14 72 637 1.6 27.5 55.3 15.7 2.85 92.88 June 3 Aug. 15 73 647 1.4 14.5 50.5 32.7 3.16 65.11 June 3 Aug. 16 74 657 1.3 11.7 49.3 36.4 3.22 58.68 June 6 Aug. 17 72 618 1.6 12.0 47.7 37.5 3.22 57.68 June 6 Aug. 18 73 626 1.6 12.1 46.2 40.1 3.25 57.78 June 7 Aug. 19 73 629 0.6 7.5 36.7 53.5 3.46 40.75 June 25 Aug. 28 64 567 5.0 39.6 43.0 7.7 2.56 120.66 June 25 Aug. 29 65 578 5.6 43.6 40.9 4.5 2.47 128.85 July 4 Sept. 12 70 657 7.7 54.6 30.7 4.7 2.33 147.84 July 4 Sept. 13 71 671 3.8 44.6 42.4 4.1 2.49 126.25 July 4 Sept. 14 72 687 3.1 38.1 44.1 3.8 2.55 115.67 July 11 Sept. 19 70 695 3.6 22.7 60.7 9.9 2.79 95.03 $/ton vs. mean grade: R2 = 0.9854, p<0.001 Mean grade vs. AHU: R2 = 0.0016, not significant Mean grade vs. days: R2 = 0.4101, p<0.01 $/ton vs. days: R2 = 0.4109, p<0.01 $/ton vs. AHU: R2 = 0.0082, not significant Mean grade vs. Tmean-10,CP: R2 = 0.0458, not significant $/ton vs. Tmean-10, CP: R2 = 0.0222, not significant Table 4. Cucumber accumulated heat unit models for selectedz machine harvests of 'Calypso' cucumber in the Willamette Valley, Oregon, 1989 Planting Days, seed Tmax-15.5 Tmax-15.5 Tmean-10 Tmean-15.5 date to harvest Grade (AHU) -CP Tmean-10 -CP Tmean-15.5 -CP June 2 68 2.61 619 546y 530x 471 181x 166 June 2 69 2.67 610 537 540 481 186 171 June 3 70 2.47 616 539 541 480 182 167 June 3 71 2.73 626 541 550 482 184 167 June 25 64 2.56 567 510 493 440 157 143 June 25 65 2.47 578 519 502 448 159 145 July 4 71 2.49 671 580 564 487 181 161 July 4 72 2.55 687 596 575 498 186 166 July 11 70 2.79 695 595 564 484 189 167 Mean 68.8 2.59 630 551 540 475 178 161 Std. Dev. 2.7 42.9 29.8 26.3 17.7 11.2 9.6 Coeff. Var.w 4.0% 6.8% 5.4% 4.9% 3.7% 6.3% 6.0% ___________________________________________________________________________________ zAll harvests for which the mean grade fell between 2.45 and 2.80. yA cold penalty is subtracted from the next day's heat units when the minimum temperature falls below 11oC. The penalty increases proportionally from 14% of the next day's units at 10o to 100% at 4o or lower. xIf the mean falls below this temperature (10o or 15.5oC, respectively), no heat units are recorded for the date. wCoefficient of variation = Standard Deviation of the Mean divided by the Mean and multiplied by 100%. Table 5. Cucumber accumulated heat unit models for machine-harvested 'Calypso', Willamette Valley, Oregon, 1989, corrected to a mean grade of 2.5 Planting Days, seed Tmax-15.5 Tmean-10 Tmean-15.5 date to harvest Tmax-15.5 -CP Tmean-10 -CP Tmean-15.5 -CP June 2 67 600 528 531 473 183 168 June 2 67 610 539 523 465 178 163 June 3 70 620 540 545 481 183 167 June 25 64 570 512 496 442 158 144 July 4 72 670 579 563 486 181 161 Mean 68 614 540 532 469 177 161 Std. dev. 3.1 32.6 22.1 22.4 15.4 9.5 8.7 Coeff. var. 4.1% 5.3% 4.1% 4.2% 3.3% 5.4% 5.4% For explanation of heat unit models and coefficient of variation, see previous table. Table 6. Effect of harvest on yield, size distribution and value per acre of eight machine-harvested pickling cucumber varieties, first planting, 1990 Tot. Wt. % in grade by weight Mean Yield Value Variety Harvest AHUz (lb) 1s 2s 3s 4s N&C grade (T/A) $/A $/T _______________________________________________________________________________________________________________ Calypso 1 673 1409 2.7 31.4 42.9 2.0 0.0 2.86 6.3 666 106 2 699 1945 1.2 17.3 49.5 29.7 2.3 3.10 8.6 713 83 3 730 2523 0.5 6.2 40.7 50.5 2.1 3.44 11.2 579 52 4 738 2840 0.4 4.8 28.6 62.8 3.4 3.59 12.6 486 39 Castlepik 1 673 1884 2.3 22.0 52.9 22.8 0.0 2.96 8.4 810 97 2 699 1923 1.2 16.3 48.9 31.1 2.5 3.13 8.5 685 80 3 730 3106 0.7 7.2 41.5 49.1 1.6 3.41 13.8 753 55 4 738 3089 0.5 6.1 32.6 60.0 0.8 3.53 13.7 598 44 Cross Country 1 673 1475 2.2 24.6 52.3 21.0 0.0 2.92 6.6 659 101 2 699 2187 1.1 10.9 40.5 46.3 1.2 3.34 9.7 599 62 3 730 2773 0.6 6.5 32.3 59.9 0.8 3.53 12.3 546 44 Discover 1 673 1456 2.3 25.8 48.6 23.3 0.0 2.93 6.5 647 100 2 699 1604 1.1 10.3 40.3 47.5 0.7 3.35 7.1 429 60 3 730 2226 0.4 4.5 29.6 64.2 1.3 3.60 9.9 376 38 4 738 1352 0.3 3.4 28.0 64.7 3.6 3.63 6.0 210 35 Primepak 1 673 500 7.8 55.0 32.0 5.2 0.0 2.35 2.2 348 157 2 699 894 3.4 28.7 48.0 17.6 2.3 2.82 4.0 434 109 3 730 1657 1.3 13.5 52.0 32.0 1.3 3.16 7.4 570 77 4 738 1100 1.3 12.3 47.9 35.1 3.5 3.21 4.9 354 72 PS50885 1 673 1873 2.7 29.4 47.6 20.3 0.0 2.86 8.3 889 107 2 699 1917 1.5 17.8 48.5 30.9 1.4 3.10 8.5 706 83 3 730 2632 0.9 6.4 41.0 50.5 1.3 3.43 11.7 623 53 4 738 2632 0.4 4.9 26.4 67.6 0.7 3.62 11.7 414 35 Regal 1 673 1314 2.4 25.8 52.6 19.2 0.0 2.89 5.8 606 104 2 699 2314 0.9 11.2 46.2 40.3 1.4 3.28 10.3 687 67 3 730 2097 0.9 9.8 40.2 47.8 1.4 3.37 9.3 547 59 4 738 2887 0.3 3.3 22.6 69.5 4.3 3.69 12.8 389 30 Sun 3509 1 673 1111 3.2 27.2 41.5 28.1 0.0 2.94 4.9 489 99 2 699 1835 1.0 12.0 44.3 42.3 0.4 3.28 8.2 543 67 3 730 2395 0.5 6.2 31.9 61.0 0.4 3.54 10.6 458 43 4 738 2865 0.5 3.8 18.9 74.9 1.9 3.72 12.7 349 27 zAHU: accumulated Celsius heat units, Sum of Tmax-15.5, with a maximum temperature cutoff of 32C (90F). Table 7. Main effects of variety and harvest on yield, size distribution, and value per acre of eight cucumber varieties, first planting, Marion County, Oregon, 1990 % in grade by weight Mean Yield Value Valuez Treatment 1s 2s 3s 4s N&C grade (T/A) $/A $/T loss (%) Variety Calypso 1.3 14.9 40.4 41.5 2.0 3.18 9.7 611 70 64 Castlepik 1.2 12.9 44.0 40.8 1.2 3.22 11.1 712 69 55 Cross Country 1.3 14.0 41.7 42.4 0.7 3.26 9.5 601 69 56 Discover 1.0 11.0 36.6 49.9 1.4 3.33 7.4 416 58 65 Primepak 3.5 27.4 45.0 22.5 1.8 2.83 4.6 427 104 67 PS50885 1.4 14.6 40.9 42.3 0.9 3.23 10.1 658 70 54 Regal 1.1 12.5 40.4 44.2 1.8 3.24 9.6 557 65 71 Sun3509 1.3 12.3 34.2 51.6 0.7 3.35 9.1 459 59 72 Harvest 1 3.2 30.2 46.3 20.4 0.0 2.84 6.1 639 109 --y 2 1.4 15.6 45.8 35.7 1.5 3.21 8.1 668 76 30 3 0.7 7.5 38.7 51.9 1.3 3.44 10.8 557 53 51 4 0.5 5.5 29.3 62.1 2.6 3.57 10.6 400 40 63 zThe percentage loss in crop value (dollars per ton) between the first and last harvest of the variety. yThe average cumulative percentage loss in crop value between the first harvest and successive harvests, averaged over all varieties. Table 8. Effect of harvest on yield and size distribution of nine machine-harvested pickling cucumber varieties, second planting, Marion County, Oregon, 1989 Tot. Wt. % in grade by weight Mean Yield Value Variety Harvest AHU (lb) 1s 2s 3s 4s N&C grade (T/A) $/A $/T Calypso 1 689 667 5.6 45.9 38.6 7.2 2.7 2.49 3.1 433 140 2 727 718 1.1 18.5 45.4 32.9 2.1 3.12 7.4 601 81 3 757 2678 0.5 13.1 41.7 43.1 1.6 3.29 9.5 621 65 Castlepik 1 689 1327 2.0 22.9 53.1 19.9 2.0 2.93 5.0 493 99 2 727 749 1.3 14.4 50.6 32.8 0.8 3.16 7.8 605 78 3 757 3597 0.6 10.0 34.2 53.9 1.3 3.43 12.8 675 53 Cross Country 1 689 877 3.3 33.3 46.6 13.2 3.5 2.72 3.3 386 117 2 727 338 3.6 28.1 49.4 18.9 0.0 2.84 3.5 382 109 3 757 1554 1.2 18.3 46.6 31.3 2.6 3.11 5.5 452 82 Discover 1 689 951 5.2 42.9 45.0 6.5 0.4 2.53 3.6 493 138 2 727 674 1.8 17.2 51.2 29.8 0.0 3.09 7.0 592 85 3 757 3006 0.6 9.9 38.1 48.6 2.7 3.38 10.7 609 57 Little Leaf 1 757 513 1.9 18.5 39.4 40.2 0.0 3.18 1.8 140 77 Pioneer 1 689 569 5.4 44.1 40.4 8.8 1.2 2.53 2.1 294 137 2 727 387 2.6 18.1 50.9 28.4 0.0 3.05 4.0 356 89 3 757 949 0.9 9.4 40.4 45.2 4.1 3.35 6.6 391 60 PrimePak 1 689 645 6.4 39.7 41.6 9.3 3.1 2.56 2.4 325 134 2 727 382 3.1 32.2 46.3 18.3 0.0 2.80 4.0 445 112 3 757 2081 1.1 15.9 48.7 33.2 1.2 3.15 7.4 579 78 PS50885 1 689 1068 5.7 37.9 49.0 7.0 0.4 2.58 4.0 539 134 2 727 956 1.6 15.8 39.7 42.2 0.7 3.23 11.9 849 71 3 757 2630 0.8 11.3 39.2 47.5 1.3 3.35 13.1 789 60 Regal 1 689 832 4.8 44.2 40.1 10.0 0.8 2.56 3.1 423 135 2 727 562 2.0 15.8 47.5 31.9 2.8 3.12 5.8 470 81 3 757 2954 0.7 10.1 35.6 50.7 2.8 3.40 10.5 583 55 Table 9. Main effects of variety and harvest on yield, size distribution, and value per acre of eight cucumber varieties, second planting, Marion County, Oregon, 1990 % in grade by weight Mean Yield Value Value Treatment 1s 2s 3s 4s N&C grade (T/A) $/A $/T loss (%) Variety Calypso 2.4 25.8 41.9 27.7 2.1 2.97 6.7 552 95 64 Castlepik 1.3 15.8 46.0 35.5 1.4 3.17 8.5 591 77 66 Cross Country 2.7 26.6 47.5 21.1 2.0 2.89 4.1 407 103 30 Discover 2.5 23.3 44.8 28.3 1.0 2.99 7.1 417 93 59 Pioneer 3.0 23.9 43.9 27.1 1.8 2.98 4.2 347 95 55 Primepak 3.5 29.3 45.5 20.3 1.4 2.84 4.6 450 108 41 PS50885 2.7 21.7 42.6 32.2 0.8 3.05 9.7 726 88 59 Regal 2.5 23.4 41.1 30.9 2.1 3.03 6.5 492 90 57 Harvest 1 4.8 38.9 44.3 10.2 1.8 2.61 3.3 423 129 -- 2 2.1 20.0 47.6 29.4 0.8 3.05 6.4 538 88 32 3 0.8 12.3 40.6 44.2 2.2 3.31 9.5 587 64 50 Table 10. Summary of yield and mean grade for several fields of 'Calypso' cucumber harvested by the Byron (B) and Wilde (W) harvesters, Willamette Valley, Oregon, 1990 Grower/ Planting Harvest Mean AHU to mean Tons/ Dollars/ Dollars/ Harvester date date AHU grade grade of 2.5 acre acre ton 1,B 5/29 7/31 591 2.76 560z 8.9 1037 117 1,B 5/31 8/03 621 2.74 580 5.8 695 121 2,B 6/15 8/05 592 2.68 580 6.7 761 114 3,B 6/14 8/04 591 2.61 585 6.7 841 126 4,W 6/22 8/14 673 2.86 633 6.3 666 106 6/22 8/16 699 3.10 " 8.6 713 83 6/22 8/19 730 3.44 " 11.2 579 52 6/22 8/20 738 3.59 " 12.6 486 39 7/03 8/27 689 2.49 690 3.1 433 140 7/03 8/31 727 3.12 " 7.4 601 81 7/03 9/03 757 3.29 " 9.5 621 65 zEstimated heat units required to obtain a mean grade of 2.5, based on the AHU required to reach the mean grades listed in the table. For the plantings of grower No. 4, a regression line was determined for the listed data and the AHU at grade 2.5 was estimated by extrapolation. For the other plantings, the estimate was made on the basis of the rate of change in grade in the grower 4 plantings. Table 11. Main effects of plant population, N rate, and harvest date on yield and grade of 'Castlepik' cucumber, NWREC, Oregon, 1990 % in grade by weight Mean Yield Gross Value 0-1" 1-1.5' 1.5-2" >2" N&Cz Gradey tons/acre $/acre $/ton AHUx _________________________________________________________________________________ Population 70,000/A 4.7 26.0 38.5 28.4 3.3 2.92 7.5 663 100 -- 100,000/A 4.1 21.1 42.0 30.7 2.1 3.01 10.7 899 92 -- NSw NS NS NS NS NS ** * NS N Rate 70 lb/A 3.6 21.2 42.4 29.3 3.6 3.01 9.4 798 92 -- 110 4.8 24.6 35.3 32.6 2.6 2.98 9.0 745 95 -- 150 4.7 25.0 43.1 25.3 1.9 2.91 9.0 801 102 -- NS NS NS NS NS NS NS NS NS Harvest Aug. 1 7.0 31.6 38.1 20.6 2.7 2.74 6.6 737 117 601 Aug. 6 1.8 15.6 42.4 38.6 2.7 3.19 11.6 826 75 667 ** ** NS ** NS ** ** * ** zNubs and crooks. yGrade 1 = 0-1", grade 2 = 1-1.5", grade 3 = 1.5-2", grade 4 = over 2" diameter. xAccumulated celsius heat units: sum(Tmax.-15.5C) from day after planting to harvest with maximum heat units per day set at 16.67. wNS: nonsignificant; *,**: significant at 5% and 1% levels, respectively. Table 12. Main effects of plant population and N rate on yield and grade of 'Little Leaf' cucumber, NWREC, Oregon, 1990 % in grade by weight Mean Yield Gross Value 0-1" 1-1.5" 1.5-2" >2" N&C grade tons/acre $/acre $/ton Population 35,000/A 4.3 40.9 38.2 15.8 0.8 2.66 7.9 988 125 70,000/A 5.8 51.5 35.5 6.4 0.7 2.43 9.5 1364 147 NS NS NS * NS NS * * NS N Rate 70 lb/A 3.0 48.0 38.3 9.5 1.2 2.55 10.3 1383 134 110 5.4 44.4 38.8 10.9 0.5 2.55 9.1 1249 141 150 6.5 46.8 33.3 12.9 0.5 2.55 7.8 1098 141 NS NS NS NS * NS NS NS NS Table 13. Main effects of plant population, N rate, and harvest date on yield and grade of 'PS 10588' cucumber, NWREC, Oregon, 1990 % in grade by weight Mean Yield Gross Value AHU 0-1" 1-1.5" 1.5-2" 2"+ N&C grade tons/acre $/acre $/ton Population 70,000/A 15.1 47.2 28.6 5.5 3.6 2.25 11.0 1508 164 -- 100,000/A 18.1 45.4 25.1 7.5 3.9 2.22 9.3 1215 167 -- NS NS NS NS NS NS * * NS N rate 70 lb/A 15.0 43.7 29.9 7.7 3.7 2.31 11.0 1369 158 -- 110 18.6 48.0 24.1 5.9 3.4 2.18 10.3 1436 172 -- 150 16.3 47.2 26.6 5.8 4.1 2.22 9.2 1280 166 -- NS NS NS NS NS NS NS NS NS Harvest Aug. 31 48.1 40.8 4.3 0.0 6.8 1.53 2.1 485 238 614 Sept. 4 13.3 75.0 7.7 1.7 2.3 1.98 6.9 1314 189 643 Sept. 7 3.4 39.5 45.1 9.2 2.8 2.62 13.2 1676 127 686 Sept. 10 1.6 29.9 50.4 15.1 3.0 2.81 18.4 1971 108 718 ** ** ** ** * ** ** ** **