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Standardized phenotyping is being used in tomato (Solanum lycopersicum) and potato (S. tuberosum) as part of the USDA-funded Solanaceae coordinated agricultural project (SolCAP). In tomato, a panel of 480 lines, 144 fresh market, 144 processing, 44 vintage lines, 48 landraces, and 101 related Solanum species accessions, are being grown over two seasons at multiple locations. These tomato genotypes will also be screened for over 7600 single nucleotide polymorphism markers that are being developed. Characters being phenotyped are hypocotyl color, plant habit, inflorescence (simple or compound), flower fasciation, flowering time, time to maturity, size of blossom scar, and pedicel type (jointless or jointed). Transverse and equatorial cross-sections of fruit are also being scanned to obtain measures of fruit shape and color by tomato analyzer computer software. Other fruit characters being measured are pH, titratable acidity, and soluble solids. Some useful information may come from this phenotyping and genotyping effort. However, in this author's opinion, the value of measuring some of the traits is very limited in the face of much more important breeding traits that are difficult to fit into a standardized phenotyping format. For instance, proper assessment of several fruit disorders is not being attempted, but such data might yield some invaluable marker information. Part of this is the result of funding limitations for the phenotyping effort. However, a major benefit of the SolCAP analysis will be the development of markers that will differentiate the lines being studied, because there is a present lack of polymorphisms in tomato germplasm where wild species introgressions are minimal or distant in time. This will allow breeders to proactively select for recurrent parent backgrounds in backcrossing projects and may aid in the identification of associations of markers with important characteristics. As one looks to the future of standardized phenotyping, there are some important traits that will be difficult to phenotype such as tomato flavor, which is quite subjective and for which there are no good objective measures.
During 1998 and 1999, `Genesis' triploid watermelons [Citrullus lanatus (Thunb.) Matsum. & Nak.] were grown in large blocks with a single row of the diploid `Ferarri' planted as a pollinizer in the middle. A once-over harvest each year was made in harvest lanes 0, 1.5, 3.0, 4.5, 6.0, 7.5, and 9.0 m perpendicular distances from the pollinizer row. Individual fruit were weighed and counted. Data from both years indicated a similar distribution of triploid fruit with respect to distance from the pollinizer row. The greatest number of triploid fruit per unit land area was in the harvest row 3.0 m from the pollinizer row. When distance from the pollinizer row was 6.0 m or greater, triploid fruit numbers diminished substantially. Yield estimates made each year using the fruit density data suggested that a 1 pollinizer: 4 triploid ratio gave the maximum total triploid fruit yield per hectare for 1.5-m row spacings. These results should prove useful in designing field planting strategies to optimize triploid watermelon production.
During 1998 and 1999, `Genesis' triploid watermelons were grown in large blocks with a single row of the diploid `Ferarri' planted as a pollinizer in the middle. A once-over harvest of triploid watermelons was made each year in harvest lanes 0-, 1.5-, 3.0-, 4.5-, 6.0-, 7.5-, and 9.0-m perpendicular distances from the pollinizer row. Individual fruit were weighed and counted. Data from both years indicated a similar distribution of triploid fruit with respect to distance from the pollinizer row. The greatest number of triploid fruit per unit land area was in the harvest row 3.0 m from the pollinizer row. When distance from the pollinizer row was 6.0 m or greater, triploid fruit numbers diminished substantially. Yield estimations made each year using the fruit density data suggested that a 1 pollinizer: 4 triploid ratio gave the maximum total triploid fruit yield per hectare for 1.5-m row spacings. These results should prove useful in designing field planting strategies that seek to optimize triploid watermelon production.
A commercial lowbush blueberry (Vaccinium angustifolium Ait.) field deficient in leaf N and P was used to compare organic and inorganic fertilizers. In a RCB design with eight replications of 12 treatments, experimental plots received 33.6 or 67.2 kg·ha-1 rates of N (urea), P (23% phosphoric acid), N + P (DAP), N + P + K (5-10-5), or N + P + K (fish hydrolysate, 242). Fertilizer containing N alone was as effective in raising N leaf concentrations as those containing N and P. However, leaf P concentrations were raised more by fertilizer providing N and P than only P. Fish hydrolysate fertilizer was as effective as 5-10-5 in raising leaf N, P, and K concentrations in prune and crop year leaf samples. At the 67.2 kg·ha-1 rate, fish hydrolysate, N, NP and NPK increased stem length, N and NP increased flower bud density and fish hydrolysate, N and NPK increased yield compared to the control.
Production of triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] transplants is hindered by poor, inconsistent emergence, and frequent seed coat adherence to cotyledons. Seed coat adherence leads to weakened and slow growing plants. High seed costs, coupled with stand establishment problems, discourages transplant producers from growing this crop. Improvement of triploid watermelon emergence will lessen financial risks to growers and transplant producers and will provide a more reliable production system. Mechanical scarification was evaluated as a means to overcome inconsistent emergence and seed coat adherence. Seeds of `Genesis' triploid watermelon were placed in a cylinder with 100 g of very coarse sand (1.0 to 2.0 mm diameter) and rotated at 60 rpm for 0, 6, 12, 24, and 48 hours in a series of experiments. Number of emerged seed was recorded daily, to obtain emergence dynamics. No significant differences were observed in seed coat adherence among treatments. The longest duration of scarification However, enhanced emergence as compared to the control in three of four experiments. These data support earlier suggestions that a thick or hard seed coat is a factor contributing to poor germination and emergence of triploid watermelons.
Transplants for both vegetable and floral crops are produced in a number of various sized containers or cells. Varying container size alters the rooting volume of the plants, which can greatly affect plant growth. Container size is important to transplant producers as they seek to optimize production space. Transplant consumers are interested in container size as it relates to optimum post-transplant performance. The following is a comprehensive review of literature on container size, root restriction, and plant growth, along with suggestions for future research and concern.
Age and cell size can have various effects on subsequent transplant production. The interaction of the two have not been studied in triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai]. Seedless watermelon production is costly due to high seed prices, therefore it is necessary to optimize transplant performance in the field, and it is often thought that triploid watermelons are less hardy than their diploid counterparts. A 3 × 3 factorial design was established for 2 years to determine the effects of cell sizes 1.5, 3.4, and 7.9 inch3 (25, 56, and 130 cm3) and transplant age (4, 6, and 8 weeks) on the triploid watermelon `Genesis'. The diploid cultivar `Ferrari' was also planted for comparison. Seedling survival was affected by transplant age in 1997, and by cell size in 1998. Early main vine growth showed significant interaction between transplant age and cell size, with older transplants grown in the largest cells producing the longest vines. Early yield of 6-week-old transplants of `Genesis' was higher than 4- or 8-week-old transplants in 1997. Eight-week-old transplants of `Ferrari' outperformed younger transplants in 1997 and 1998. Results show that `Genesis' triploid watermelon transplants could be handled similarly to the diploid `Ferrari' without consequence.
Eight commercial lowbush blueberry fields received preemergent application of diammonium phosphate at 0, 44.8, or 89.6 kg P/ha. Leaf samples taken in July of the application year showed a linear increase in P concentration with increasing DAP application. However, P concentrations in soil samples were not raised by DAP. Stem length, branching, and the number of flower buds per stem increased with DAP application. Yield, obtained by hand raking the 3 × 9-m treatment plots, increased with increasing rate of DAP. The average yield increase in response to 44.8 and 89.6 kg P/ha from DAP was 824 and 1679 kg/ha, respectively.
Seeds of triploid watermelons [Citrullus lanatus (Thunb.) Matsum & Nakai] often germinate poorly, which prevents adequate stand establishment in both field and greenhouse environments. Methods of improving germination and emergence of these expensive seeds would reduce overall risk to growers, thus increasing the crop's market prominence. Seeds of `Genesis' triploid watermelon were subjected to three treatments: 1) seedcoat removal; 2) clipping the seedcoat opposite the radicle end; or 3) no seedcoat alteration; and were germinated on agar in the presence of a 0%, 1%, 2%, 4%, or 8% aqueous H2O2 at constant 28 °C in the dark. Seedcoat removal, clipping, and all levels of H2O2 increased final germination percentages relative to the control (no seedcoat alteration, no H2O2) by as much as 70%. Hydrogen peroxide levels >2% resulted in severe injury to germinating seeds. These findings suggest that germination barriers of triploid watermelon are seedcoat related, and that seedcoat alteration and H2O2 can overcome these barriers.
Production of triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] transplants is hindered by low and nonuniform emergence, and seedcoat adherence. Seedcoat adherence leads to weakened and slow-growing plants. High seed costs are prohibitive to many transplant growers. Improvement of emergence would lower financial risks to growers and transplant producers. Mechanical scarification was examined as a means to decrease the impact of both problems. Seeds of `Genesis' triploid watermelon were placed in a cylinder with 100 g of very coarse sand and rotated for 6, 12, 24, and 48 hours at 60 rpm. Nontreated seeds were used as a control. Data were taken daily on emergence and seedcoat adherence. The experiment was repeated at three temperature regimes. No significant differences were observed in seedcoat adherence. Scarification, however, did significantly improve emergence under test conditions.