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C.S. Vavrina Introduction In 1998-99 season, over 37,000 acres of tomatoes were grown in Florida. The acreage has fallen over the past several years due to expanding competition, increasing regulations, and environmental constraints. To remain competitive, FL tomato growers must increase yields and offset production costs. Humitron G-Micro is a 50% humic acid with magnesium (1%), sulphur (2%), boron (0.05%)), copper (0.05%), iron (4%), manganese (0.05%), and zinc (2%). K-Tionic is a fulvic acid organic complex. Preliminary tests in 1998 indicated that the application of K-Tionic (KT) both alone and in combination with Humitron G Micro (HGM) could increase the number and total weight of extra large (XL) tomatoes compared with the untreatred control. The objective of this study was to apply HGM and K-Tionic for a second year in accordance with a Grupo Bioquimico Mexicano company protocol on drip irrigated tomatoes to further test the hypothesis of enhanced crop growth and yield. Methods A trial was established at the Southwest FL Research and Education Center of the University of Florida in Immokalee, FL. A standard methylbromide fumigated (320 lbs./A, broadcast), granular base fertilized (30N-96P-48K), plastic mulched (white on black, 1.5 mil), 32" wide bed was prepared on Sept. 18, 1998 allowing two weeks for fumigant action. Holes were punched in a single row, 18" in-row pattern on 6' centers, and transplants of `Sanibel’ (Peto Seed, Saticoy, CA) fresh market tomato were planted on Oct. 16, 1998. A starter fertilizer (2 lbs./100 gal of 20-20-20) was applied to each plant at setting. Thirty-three plants were set per treatment in 50-foot plots. Soil and air temperatures during that time ranged from the high 80s to low 90s. The plots were drip irrigated with Netafim (Haifa, Israel) Streamline 80 (0.63 ID, 8 mil) which delivered 0.36 gph at 10 psi. Six replications were accomplished by running a combination of solid tubing and drip tubing down each bed to facilitate treatment application. This arrangement allowed for a control and a treated plot to exist on each bed without additional water being applied. Four treatments were imposed:
Manzate, copper, and Bravo fungicides were applied weekly to prevent the advancement of fungal diseases and bacterial spot. Various Bt's (insecticide) were also applied to reduce worm pressure. Data was taken on bloom development 30 days after planting (DAP), plant dry weight (1 plant per plot 30, 45, and 60 DAP), developing fruit (45 and 60 DAP), and yield (2 harvests of 10 plants per plot). Yield was separated into red/breaker fruit and mature green. Each color category was further subdivided into medium, large, and extra-large size. The six replications of the randomized complete block design were employed and analyzed by ANOVA (SAS) with mean separation via Fisher's Protected LSD at p<0.05 and 0.1. Results Flowering No treatment effect was noted 30 DAP on the number of open tomato blooms (Table 1). This finding was consistent with data taken in 1997, however considerably more blooms were evident in 1998 at 30 DAP, which may reflect the later planting date (i.e., more conducive to flowering.) Plant Dry Matter Accumulation & Fruit Development 30 DAP There was no treatment effect on tomato shoot (leaves and stems) dry matter accumulation 30 DAP when analyzed at p<0.05 (Table 1). This was consistent with the 1997 data. 45 DAP There was no treatment effect on tomato shoot dry weight (DW) 45 DAP when analyzed at p<0.05 (Table 1). However, at p<0.09 (LSD = 17.998) the control plants exhibited significantly more dry matter than plants from either KT treatment. 60 DAP Shoot DW 60 DAP when analyzed at p<0.05 indicated that all treatments lagged behind the control in shoot growth (Table 1). Additionally, at p<0.06 (LSD = 6.79) the control treatment showed a significant increase in the number of small fruit when compared to the KT variable rate treatment, but this did not translate to greater fruit weight either. Yield Parameters It seems apparent that the treatments (HGM, KT2%, and KT variable rate) had very little effect on tomato yield in 1998. The only factor of significance (p<0.05) noted was in the production of total red fruit. The KT2% treatment produced more red fruit, both in number (Table 2) and weight (Table 3), than either the HGM or KT variable rate treatment alone. The yield increase was however, not significantly different from the control in either case. Furthermore, the KT2% treatment produced more medium grade red fruit at both second harvest {number; p<0.06, LSD = 2.26; weight; p<0.08, LSD = 0.77} and in total {number, p<0.08, LSD = 2.28; weight; p<0.10, LSD = 0.78} than the KT variable rate treatment. The control treatment showed a similar trend (i.e., > KT variable rate) with respect to large red fruit number at second harvest, but the probability (p<0.1057) was slightly outside the limits set for this study. No significant differences were noted in green fruit production, overall grade sizing or average fruit weight (Table 4) resulting from the treatments imposed at either probability (p<0.05 or, p<0.1). Discussion The data generated in 1998 did not confirm that which was generated in 1997, however this is not uncommon in product testing. One should take care to obtain sufficient information (i.e., several years and/or seasons) on which to make an educated decision. The 1997 data showed that HGM, KT and HGM+KT treatment 45 DAP generally benefited shoot DW and while no significant effect was noted 60 DAP the controls tended to lag behind the treatments. This suggested that a stand establishment advantage might be obtained with the use of HGM and/or K-tionic. An improvement in stand establishment was not shown in the 1998 trial, however 20 days after transplanting this trial was subjected to 10 inches of rain and sub-hurricane force winds from Tropical Storm "Mitch". The impact of many hours of standing water (anoxia, treatment leaching), physical injury, and subsequent disease pressure from "target spot" all added to an environment that could readily negate any treatment effect on stand establishment. Furthermore, whereas treatment yield effects were also evident in 1997 (more overall XL fruit with KT2% and HGM+KT) this was not the case in 1998. This trial resulted in 8 lbs./plant, reflecting the state average and identical to last year’s trial production. Typically, tomato fruit yields (mature green) from efficient commercial producers in south FL fall in the 10 – 12 lbs./plant range. On a positive note, in last year’s trial KT2% was determined to be the best treatment in the trial and that was the conclusion in this year’s trial as well. Though KT2% performed quite similar to the control, it tended to "do better" than the other two treatments in the trial. The mitigating circumstances imposed on this crop during the stand establishment phase by Tropical Storm "Mitch" were extreme by any calculation. Therefore, one would be best served to initiate another trial before forming legitimate conclusions. Table 1. K-Tionic bloom count and field sample data – Fall 1998
Table 2. K-Tionic tomato trial yield data, number per plot (plot = 10 plants at 18" spacing, 6 ‘ centers)
Table 3. K-Tionic tomato trial yield data, pounds per plot (plot = 10 plants at 18" spacing, 6 ‘ centers)
Table 4. K-Tionic tomato trial yield data, average fruit weight in pounds and size categories in pounds per plot
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