The purpose of these trials was to evaluate varieties of cauliflower for summer harvest. The major desired quality is heat tolerance: the ability to withstand high temperatures without ricing and to maintain the high curd quality typical of autumn-harvested cauliflower. A second desired quality is long wrapper leaves for self-blanching.
Fully satisfactory varieties have not been available to Oregon growers. It would be helpful for both fresh market and processors to have a high quality summer crop. The possibility exists for double cropping, particularly if combined with overwintered cauliflower.
The research involved comparing common autumn-harvested varieties with named varieties and lines from several seed companies which might be useful for a summer crop. These are the fourth and fifth in a series of such trials dating from 1978. Most varieties reported here were also included in earlier trials.
Methods
Twenty-four (1983) or 14 (1984) lines of cauliflower were seeded on April 18 (1983) or April 19 (1984) and placed in a glasshouse. Seedlings were transplanted to the field on May 19, 1983, and May 22, 1984. Land preparation included broadcast and incorporation of 1,000 pounds/acre of 10-20-10, 0.75 pounds/acre trifluralin, and 1.3 pounds/acre chlorpyrifos. Diazinon, as a 1 pound/acre drench, was applied in June for root maggot control, along with 5 pounds Solubor/acre. Bacillus thuringiensis insecticide was applied for worm and looper control in July. A total of 150 pounds N/acre was sidedressed as urea or calcium nitrate during June. Plant spacing was 3 feet x 12 feet. Each variety was replicated three times in randomized block design. Heads were harvested at 2- to 4-day intervals. Heads were not tied so adequately self-blanching varieties could be determined.
Results and Discussion
Sources of seed, yields, and harvest spans are listed in Tables 1 and 2. Table 3 contains comments on curd quality.
Harvest period weather was extremely mild in 1983. During the harvest period of June 29 to July 29, the mean maximum temperature was 74°F, exceeding 80°F only six times. The mean minimum temperature during harvest was 53°F. Pre-harvest temperatures were stressful only in late May, between one and two weeks after transplanting. The mean maximum temperature during harvest in 1982 was 81°F. The mild weather would be expected to lead to a high percentage of high quality heads. This was the case for several varieties which had higher quality in 1983 than in earlier trials, including Dok Elgon, King, Matra, Snowball 42, and Suprimax.
Highest gross yields in 1983 were obtained with Matra, EO-222, Suprimax, and Snowball 42. However, highest yields of Grade #1 heads were obtained with Andes, Snowball 123, Suprimax, and Silverstar.
Harvest period weather was warmer in 1984 and was moderately stressful. Solar radiation and light intensity were higher than normal. During the harvest period of July 9 to August 3, the mean maximum temperature was 81°F, exceeding 90° on 5 days. Mean minimum temperature during harvest was 52°. There was no precipitation and virtually no cloud cover during harvest. Plant size and curd cover were generally poorer than usual. These conditions would be expected to lead to poor curd quality, particularly since the heads were not tied.
Highest gross yields were obtained with the autumn cauliflower Vernon, followed by Andes, Dok Elgon, and White Top. Highest yields of Grade #1 heads were obtained with Andes, Silverstar, and Vernon. Only Andes and Silverstar produced more than 50% #1 heads.
Quality of all varieties declined. Varieties such as White Summer, White Top, Snowball 123, and Dok Elgon, which have all performed well in some years, fared poorly in 1984. Vernon has not previously been evaluated and appears to offer some promise because of good head size and some heads with excellent curd quality.
Silverstar has performed consistently well every year. Andes was introduced to the trials in 1983 and had the highest percentage of #1 heads in both 1983 and 1984.
Table 1. Source, yield, and grade of summer cauliflower varieties, 1983 Harvest period Mean head Gross yield Yield of #1 % #1 Variety Source First Peak Last wt. (lbs) (T/A) heads (T/A) heads Alpha Paloma 7Z 6/29 7/3 7/15 0.8 3.1 2.4 68Y Andes 6 7/15 7/18 7/22 1.5 7.3 6.2 87 Christmas White 7 7/18 7/18 7/20 0.9 4.5 0.5 13 Dok Elgon 1 7/15 7/20 7/25 1.3 6.4 3.7 59 Dominant 1 7/15 7/20 7/29 1.3 6.4 2.6 41 Duromax 6 7/15 7/20 7/29 1.2 5.7 1.4 24 Early Abundance 7 6/28 6/28 7/11 0.4 2.1 0.6 18 Early Snowball A 8 6/29 7/11 7/15 0.9 4.4 1.7 43 Fortados 6 7/15 7/15 7/15 1.3 6.2 1.1 24 Imperial 10-6 2 7/15 7/18 7/18 1.6 7.2 2.9 41 King 1 6/29 7/11 7/15 0.9 3.7 2.9 75 Matra 6 7/05 7/25 7/29 2.3 10.5 4.5 45 Raket 7 7/01 7/11 7/15 1.0 4.9 2.5 56 Silverstar 5 7/15 7/18 7/25 1.6 7.4 5.6 80 Snowball 42 4 7/18 7/22 7/25 1.7 7.9 3.1 44 Snowball 76 4 7/18 7/18 7/25 1.5 7.4 1.8 22 Snowball 123 2 7/18 7/18 7/25 1.8 8.8 5.7 60 Snow Pack 8 7/11 7/18 7/29 1.6 7.7 3.6 52 Snow White 8 7/15 7/15 7/15 1.1 5.2 0.6 14 Suprimax 6 7/15 7/18 7/18 1.8 8.2 5.8 76 White Summer 3 7/15 7/22 7/25 1.4 6.8 5.3 77 White Top 7 7/15 7/18 7/25 1.6 7.4 4.3 59 E0-222 4 7/15 7/18 7/25 1.6 8.1 0.8 10 LSD(0.05) 0.3 1.2 1.1 Z1: Elsoms, 2: Jos. Harris, 3: Stokes, 4: Ferry Morse, 5: Rijk Zwaan, 6: Royal Sluis, 7: Territorial Seed Co., 8: Petoseed. YCurd white, free of defects. No leaves, bracts in curd. Dense and tight. Percent by number. Table 2. Source, yield, and grade of summer varieties, 1984 Harvest period Mean head Gross yield Yield of #1 % #1 Variety Source First Peak Last wt. (lb) (T/A) heads (T/A) heads Andes 6Z 7/19 7/23 7/30 1.6 7.6 5.2 63 Cervina 6 7/23 7/26 8/03 1.3 6.0 0.4 8 Dok Elgon 1 7/19 7/23 8/03 1.5 6.9 0.8 12 Dominant 1 7/09 7/19 7/30 1.1 5.3 0.8 13 Fortuna 5 7/16 7/23 8/03 1.1 5.0 2.0 30 Matra 6 7/13 7/19 7/26 1.4 6.5 0.8 17 Silverstar 5 7/16 7/19 7/30 1.3 6.2 3.9 61 Snowball 42 4 7/13 7/26 7/30 1.2 5.5 0.0 0 Snowball 123 2 7/09 7/19 7/26 1.1 5.4 0.0 0 Snow Pack 8 7/13 7/16 7/23 0.9 4.2 0.5 12 Suprimax 6 7/09 7/13 7/19 0.8 3.7 0.0 0 Vernon 6 7/16 7/30 8/03 1.9 9.3 3.7 42 White Summer 3 7/16 7/19 7/26 0.8 4.0 0.9 13 White Top 7 7/16 7/26 8/03 1.4 6.7 0.5 4 LSD(0.05) 0.3 1.3 1.4 Z1: Elsoms, 2: Jos. Harris, 3: Stokes, 4: Ferry Morse, 5: Rijk Zwaan, 6: Royal Sluis, 7: Territorial, 8: Petoseed. Table 3. Comments on summer cauliflower varieties, 1983 and 1984 Alpha Paloma: Short to medium size plant, spreading. Large leaves, fair cover. Early maturity. Small heads, good quality. Andes: Small plants with upright leaves, good cover. Good yield, very high quality. Small (20%) percentage of discolored curd. Few(17%)ricey heads. Christmas White: Large but spreading plant. Large leaves but poor to fair cover. Heads small, yellow curd. Cervina: Grown out of its proper season. High proportion (62%) of ricey heads. Dok Elgon: Medium size, upright plant with fair to good cover. Fair yield and quality. Some yellowing of curd in 1983. In 1984, curd was fuzzy, contained bracts, leaves. Dominant: Medium size, spreading plant. Fair cover. Only fair quality with 39% ricey and 35% yellow curd. Duromax: Lacks vigor early in season. Upright leaves, fair cover. Low curd quality. Many ricey or yellow heads. Early Abundance: Small plant, spreading, poor cover. Very early, low yield and quality. Heads often ricey. Early Snowball A: Medium size plant, spreading, poor cover. Early. Poor yield, fair quality. Curd tends to be ricey, yellow. Fortados: Medium size plant, somewhat upright leaves with fair cover. Very concentrated maturity. Low quality from yellow curd. Fortuna: More than half the heads had yellow curd. Imperial 10-6: Medium size plant, somewhat upright leaves. Good yield but quality low this year. Ricey and discolored curd. King: Medium vigor, spreading, variable. Poor to fair cover. Very pale leaves. Low yield but high curd quality. Small heads. Matra Low to medium vigor, upright leaves. Good cover, pale leaf color. Excellent head size and gross yield but only fair quality. High percentage of yellow (42%) and fuzzy (21%) curd. Raket: Fairly vigorous, spreading habit. Fair cover. Early maturity. One pound heads of fair quality. Silverstar: Low to medium vigor early in season. Upright with good cover. Good yield, excellent quality. Attractive heads. Snowball 42: Medium vigor, upright, good cover. Late maturity. Good yield, fair quality. Curd tended to be yellow, ricey. Snowball 76: Low to medium vigor, spreading to upright. Good cover. Late maturity. Good yield, poor quality. Ricey, yellow curd. Snowball 123: Medium vigor, spreading to upright. Good cover. Good yield and quality in 1983, but some heads with yellow or purple curd, ricey. Most heads had yellow curd in 1984. Snow Pack: Medium vigor, spreading, fair cover. Good yield, fair quality. Yellow curd (71% in 1984). Snow White: Medium vigor, spreading, good cover. Very concentrated maturity. Mostly yellow curds. Suprimax: Good vigor, upright, good cover. Pale leaves. Good yield and quality in 1983 but high percentages of yellow (48%) and ricey (43%) curd in 1984. Vernon: High yield, good head size, but 46% of heads off-color. White Summer: Medium vigor, upright. Good cover. Very dark green leaves. Late maturity. Fair to good yield with very good quality. White Top: Medium to very vigorous, upright, good cover. Good yield, better than average quality in cooler summers. Approximately one-third of heads with yellow curds. EO-222: Variable vigor, spreading. Fair cover. Good yield but poor quality. Heads ricey, yellow.