Abstract
N,N-bis(phosphonomethyl)glycine (glyphosine) was sprayed at 0, 200, 400, 800, 1600 ppm on vine foliage of ‘PMR-45’ muskmelon (Cucumis melo L.) once about 2 weeks after initial flowering. Branch length and number of leaves were reduced at 1600 ppm. Melon weight was increased at 200 ppm about 6.6%, while soluble solids content was increased at all concentrations above the control about 10%. Both effects were most evident toward the end of the season. Triacontanol, applied at 0.01, 1.0, and 10.0 ppm as a foliar spray at the 8 to 10 leaf stage had no effect on muskmelons.
Abstract
Muskmelons (Cucumis melo L.) at standard harvest maturities tolerated mechanical stresses, such as dropping 90-120 cm or squeezing with 31.8 kg force, without showing increased damage rates. There were no important differences found between 4 cultivars and 1 breeding line.
The effect of summer cover crop and management system on subsequent fall romaine lettuce (Lactuca sativa L.) and spring muskmelon (Cucumis melo L.) growth and yield was evaluated in the Coachella Valley of California from 1999 to 2003. Cover crop treatments included: 1) cowpea [Vigna unguiculata (L.) Walp.] incorporated into the soil in the fall (CPI), 2) cowpea used as mulch in the fall (CPM), 3) sudangrass [Sorghum bicolor (L) Moench] incorporated into the soil in the fall (SGI), and 4) a bare ground control (BG). Management system treatments included: 1) conventional system (CON), 2) integrated crop management (ICM), and 3) organic system (ORG). Cowpea cover crop, either incorporated or used as surface mulch, increased lettuce growth and yield by increasing biomass allocation to lettuce leaf and leaf area growth. Cowpea mulch decreased muskmelon leaf and biomass growth and reduced muskmelon yield. Sudangrass produced more biomass than cowpea and reduced lettuce growth and yield. However, in the following spring, the SGI treatment had the highest muskmelon yield. Lettuce growth was significantly affected by management system, while muskmelon growth at the early stage was unaffected. The organic system reduced both lettuce and muskmelon yield compared with CON and ICM management systems.
Root Feed is a product developed by Stoller Enterprises, Inc., to enhance crop productivity and quality. Weekly application of Root Feed in drip-irrigated crops was found to be the most effective frequency of application. Root Feed increased the number of the largest melons and total melons by over 50% and also increased fruit °Brix (soluble solids). Moreover, it was observed that a number of pests were suppressed with Root Feed, namely, whiteflies, a cucurbit virus, and downy mildew.
Abstract
Concentrations of soluble solids (SSC) in fruits of Cucumis melo L., cv. PMR 45, were positively correlated with 2 physical measures of soil samples from producing fields: a) the degree of cracking which occurred during dehydration, and b) the rapidity with which water or a CaSC>4 solution percolated the soils. Very low SSC was associated with sandy, non-cracking soils, which in addition permitted only low rates of percolation. Low SSC also was found to be associated with soils having subsurface hardpans or dense subsoil strata, and also with the distance to lower bounds of plant containers and experimentally placed barriers which obstructed downward root growth. SSC, under adverse conditions, varied further as a function of fruit numbers per plant.
A common practice for the irrigation management of muskmelon (Cucumis melo L. reticulatus group) is to restrict water supply to the plants from late fruit development and through the harvest period. However, this late fruit development period is critical for sugar accumulation and water stress at this stage is likely to limit the final fruit soluble solids concentration (SSC). Two field irrigation experiments were conducted to test the idea that maintaining muskmelon plants free of water stress through to the end of harvest will maximise sugar accumulation in the fruit. In both trials, water stress before or during harvest detrimentally affected fruit SSC and fresh weight (e.g., no stress fruit 11.2% SSC, weight 1180 g; stress fruit 8.8% SSC, weight 990 g). Maintaining plants free of water stress from flowering through to the end of harvest is recommended to maximise yield and fruit quality.
A protocol for high-frequency somatic embryogenesis in Cucumis melo L. was developed using `Male Sterile A147 as a model cultivar. Basal halves of quiescent seed cotyledons were cultured on embryo induction (EI) medium containing concentration ranges of the auxin 2,4-D and the cytokinins BA, Bin, TDZ, or 2iP before transfer to embryo development (ED) medium. Medium with 2,4-D at 5 mg·liter-1 and TDZ at 0.1 mg·liter-1 was superior, with 49% of explants responding and an average of 3.3 somatic embryos per explant (6.8 somatic embryos per responding explant). More explants produced embryos when incubated on EI medium for 1 or 2 weeks (30% and 33%) than for 3 or 4 weeks or with no induction. However, 2 weeks was 2.9 times better than 1 week in terms of number of embryos per explant. One week of initial culture in darkness, followed by a 16 hour light/8 hour dark photoperiod, produced more responding explants (26%) than two or more weeks in darkness or no dark period at all; but 1 and 2 weeks of darkness resulted in a similar number of embryos per explant (2.1 and 2.8). Sucrose concentration in EI and ED media had a highly significant effect on embryo induction and development. EI medium with 3% sucrose resulted in more embryogenic explants than EI medium with 1.5% or 6% sucrose. However, treatments with 3% sucrose in EI medium and 3% or 6% sucrose in ED medium produced significantly more embryos per explant (8.5 and 11.9) than other treatments. Treatments did not affect embryo induction directly and regeneration per se but, instead, frequency and efficiency of somatic embryo development. The optimal treatments were tested with 51 other commercial varieties. All varieties underwent somatic embryogenesis, exhibiting a response of 5% to 100% explant response and 0.1-20.2 embryos per explant. Chemical names used: N-(phenylmethyl)-lH-purin-6-amine (benzyladenine or BA); N-(2-furanylmethyl)-lH-purin-6-amine (kinetin or BIN); N-phenyl-N'-1,2,3-thiadiazol-5-ylurea (thidiazuron or TDZ); N-(3-methyl-2-butenyl)-lH-purin-6-amine (2iP); (2,4-dichlorophenoxy) acetic acid (2,4-D).