Evaluation of grafting for the mature green tomato production system

Transcription

1 Evaluation of grafting for the mature green tomato production system Brenna Aegerter Scott Stoddard UCCE San Joaquin Co. UCCE Merced Co. University of California Cooperative Extension Minghua Zhang & Mike Grieneisen Department of Land, Air & Water Resources University of California, Davis California Department of Food & Agriculture Specialty Crop Block Grant California Department of Pesticide Regulation Pest Management Research Grant 16 PML R004

2 Why graft tomatoes? Increase in vigor, fruit size and yield Combine features of two varieties Scion: Desireable fruit traits Rootstock: Increased vigor Resistance and/or tolerance to soil-borne disease Increased stress tolerance Source: (Plug Connection)

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4 Field trial experimental plan Source of grafted plants: Growers Transplanting, Salinas Plot size: 40 feet, with a minimum of 20 plants per plot Bed configuration: 60 beds, 20 spacing in row Replicates: four, randomized complete block design Treatments (scion/rootstock combinations) Scions: Bobcat, HM1794, Dixie Red, Galilea (Roma) Rootstocks: Maxifort, DR0138TX, BS All combinations of the above, plus non-grafted controls

5 Sterile trays and sterile media hand seeded early March, five weeks before grafting date Grafting clips are added to rootstock Rootstock & scion plants cut at 45⁰ angle And scions are placed so that the two surfaces align. Grafting is most successful if the two plants are of similar diameter

6 Repeat 230 times per tray. and do 24 trays in all. Eight more trays held the non-grafted control plants. The grafted plants are held in a healing room at % humidity and 80⁰F for about a week.

7 MARKET YIELD (TONS/AC) a bc 17.5 ab 27.8 ab c 16.0 bc MAXIFORT DR0138TX BS NON-GRAFTED MAXIFORT DR0138TX BS NON-GRAFTED MAXIFORT DR0138TX BS NON-GRAFTED MAXIFORT DR0138TX BS NON-GRAFTED BOBCAT HM1794 DIXIE RED GALILEA

8 2016 trial, San Joaquin County ROOTSTOCK MEANS Total fruit yield v Market yield v Size distribution (% fruit by weight) x Maturity Vigor (T/A) difference (T/A) difference X-large Large Medium (% red) rating y NDVI z MAXIFORT 34.2 a (33%) 25.5 a (31%) DR0138TX 30.7 a (19%) 23.3 ab BS ab 20.9 b NON-GRAFTED 25.7 b 19.5 b Rootstock effect P value (round types only) sig. interaction of scion & rootstock effects < CONTRAST: GRAFTED VS (23) 23.2 (19) NON-GRAFTED Contrast P value Means in the same column followed by the same letter are not significantly different according to Tukey's HSD test. v Total fruit weight includes culls and undersize fruit, while marketable yield excludes these two categories w Percentage difference in yield of grafted plants compared to the non-grafted controls. x Size distribution of marketable fruit based on USDA sizing standards. Note that cv. Galilea is a Roma-type which follows different sizing standards than round types. y Vigor of the vines evaluated visually just before harvest and assigned a rating based on a scale from 1 to 5. 1 = vines small, fruit coverage poor, new growth little to none. 2 = vines medium sized, covering bed, fruit coverage weak, new growth little to some. 3 = vines medium to large, fruit coverage good, new growth good. 4 = vines large, fruit coverage excellent, new growth very good. 5 = Vines huge, fruit coverage excellent, new growth significant. z Normalized difference vegetation index (NDVI) measurements made with a handheld meter held over the bed (Trimble Greenseeker)

9 (ALL ON A PER ACRE BASIS) CONVENTIONAL GRAFTED DIFFERENCE plant spacing 20" spacing 24" spacing plants per acre 5,227 4,356 seed (conventional $0.022 each) $ 115???? transplant nursery (conventional $ each) $ 146???? other cultural costs (excl. above & harvest) $ 1,180 $ 1,180 SAME YIELD ASSUMPTIONS (tons per acre) 16TONS 21.6TONS 35% HIGHER YIELD ASSUMPTIONS (25-lb boxes per acre) 1,280 BOXES 1,728 BOXES HARVEST costs (pick, haul, pack) $3.78 per box $ 4,838 $ 6,532 35% HIGHER GROSS REVENUE at $5 per box $ 6,400 $ 8,640 $ 2,240 at $6 per box $ 7,680 $10,368 $ 2,688 at $7 per box $ 8,960 $12,096 $ 3,136 GROSS REVENUE minus operating expenses (excl transplant costs) at $5 per box $ 382 $ 928 $ 547 at $6 per box $ 1,662 $ 2,656 $ 995 at $7 per box $ 2,942 $ 4,384 $ 1,443 At $7/box, 35% yield increase justifies an increase from $ 0.03 to $0.36 per transplant

10 Source: Djidonou, et al. (2013) Economic analysis of grafted tomato production in sandy soils of northern Florida. HortTechnology 23(5):

11 Challenges Higher establishment costs, higher risk Plant availability, automation of grafting No rootstocks with resistance to Fusarium wilt race 3 or Verticillium wilt race 2 Location of graft union relative to soil surface Variability, rootstock x scion interactions

12 Thank you and any questions?