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- Author or Editor: Peter Stoffella x
Sweet Spanish onion (Allium cepa L. cv. Granex 33) was transplanted in two, three, or four rows per bed at 7.6, 15.2, or 22.9 cm in-row spacings resulting in plant populations ranging from 41,000 to 246,000 plants/ha during Winter 1991. Interactions between number of rows per bed and in-row spacings were nonsignificant for onion yield and bulb size traits. As number of rows per bed increased or in-row spacings decreased, marketable onion yield linearly increased and mean bulb size (g/bulb) decreased. Percentage of small, medium, and large bulbs was unaffected by number of rows per bed, but percentage of small and medium-sized bulbs increased and percentage of large bulbs decreased as in-row spacing decreased. Onion yields linearly increased, but at the expense of smaller-sized bulbs, whether plant populations were increased by more rows per bed or narrower in-row spacings.
Abstract
Total root biomass of 23 field-grown cultivars of tomato (Lycopersicon esculentum Mill.) was partitioned into basal-root and taproot components during Fall 1980 and Spring 1981. Weights of basal roots (originating within the lower one cm of the hypocotyl and one cm of the upper taproot) differed among cultivars during both seasons. For each cultivar, basal roots contributed the largest proportion of the total root biomass. No difference in taproot weights occurred among cultivars. Adventitious roots were minimal and were not measured. ‘Market Hybrid 58’ and ‘Casino Royale’ had larger total and basal root weights than ‘Burgis’, ‘Florida 1A’, and ‘Florida IB’ during both seasons. Stem diameter was significantly correlated with total and basal root weights. Results suggest that root morphological differences among tomato cultivars are restricted to basal roots.
Peat is used extensively in the nursery industry as a primary component in commercial “soilless” potting media. The increased use of peat as an organic amendment with superior water-holding capacity is challenged by economic and environmental pressures. Developing inexpensive and nutrient-rich organic media alternatives can potentially reduce fertilization rates, irrigation rates, and ultimately, nursery costs. In addition, controversy over the effects of peat mining has inspired a national search for peat substitutes. With our burgeoning population, it is logical to screen waste products as potential alternatives to peat. Growth of Pachystachys lutea Nees. (Golden Shrimp Plant) transplants was evaluated in media containing 0%, 25%, 50%, 75%, or 100% compost derived from biosolids and yard trimmings. Compost was amended with a commercial peat- or coir-based media. As compost composition in the peat or coir-based media increased from 0% to 100%, carbon/nitrogen (C/N) ratios decreased, and media stability, N mobilization, pH, and electrical conductivity (EC) increased. Bulk density, particle density, air-filled porosity, container capacity, and total porosity increased as more compost was added to either peat- or coir-based media. Plants grown in media with high volumes of compost (75 or 100%) had reduced leaf area and reduced shoot and root DW than the controls (no compost). Regardless of percentage of compost composition in either peat or coir-based media, all plants were considered marketable after 8 weeks.
Florida citrus has had an average annual on-tree-value of ≈1 billion dollars during the past decade in Florida. Nearly all of the 845,260 acres of citrus in Florida is produced on grafted trees consisting of a commercial scion cultivar and a rootstock selected specifically for local soil, environment, and pest pressures. With vastly different root-zone environments, ranging from deep sands to drained and cleared pine Flatwoods, a large number of different rootstocks are utilized. These rootstocks are started from seed at more than 100 commercial nurseries statewide, which currently produce an estimated 6 million trees a year. Although the optimum germination conditions, basic physiological performance, and adaptability of many rootstocks are known, there has been minimal investigation on early root development in seedling trays at the nursery. Four hundred seedlings of `Swingle' citrumelo (Citrus paradisi Macf. `Dunacn' × Poncirus trifoliata), `Smooth Flat Seville', `Volkamer' lemon (Citrus volkameriana), and `Sun Chu Sha' mandarin were seeded in a randomized block experimental design and grown at a commercial nursery. Seedling root systems (100/rootstock) were analyzed for a number of variables using the Rhizo (Regent Instruments, Inc.) software package and a dual light source scanner. Using the SAS general linear model procedure, hypothesis testing revealed rootstock selection had a significant effect on total root length, total root surface area, total root volume, number of root tips, number of root forks, root dry weight, and stem diameter. For most characteristics, rootstock genotype accounted for a greater portion of variability than samples (plant to plant variability).
The utilization of imidacloprid in controlling silverleaf whitefly (SLWF) (Bemisia argentifolii Bellows and Perrin) and its associated disorder tomato (Lycopersicon esculentum Mill.) irregular ripening (TIR) was investigated under field conditions. Tomato seedlings were transplanted into the field and drenched with 0.0, 14.5, 24.0, or 43.5 mg a.i./plant of imidacloprid during Fall 1995 and Spring 1996. Adult SLWF populations were reduced in plots drenched with imidacloprid as compared with the untreated control plots during both growing seasons. In the fall, the low, medium, and high rates of imidacloprid reduced the percentage of tomato fruit with external tomato irregular ripening symptoms from 33.4 in the untreated control to 1.4, 0.3, and 0.7, respectively. The percentage of fruit with internal symptoms was reduced from 83.8 in the untreated control plot to 14.2, 4.0, and 6.1 for the low, medium, and high rates of imidacloprid, respectively. In the spring experiment, the incidence of external TIR symptoms in all plots was minimal (<1%), but the higher rates of imidacloprid reduced the incidence of internal symptoms relative to the untreated control. Chemical name used: 1-[(6-chloro-3-pyridinyl) methyl]-N-nitro-2-imidazolidinimine (imidacloprid).
Mature-green and mature-red tomato (Lycopersicon esculentum Mill.) fruit were harvested from spring- and fall-grown plants infested with sweet potato whitefly (SPWF; Bemisia tabaci Gennadins). The mature-green fruit were either ripened at 20 to 22C or cold-stored at 10 to 13C for 3 weeks and then were allowed to ripen at 20 to 22C. There was no significant difference in the appearance of either external or internal tomato irregular ripening (TIR) symptoms between the two storage–ripening regimes or in the appearance of internal TIR symptoms among the two storage regimes and vine-ripened tomatoes. Thus, removing the tomatoes from the SPWF during ripening does not reduce TIR symptoms. About half of the mature-green tomatoes, ripened with or without cold storage (10 to 13C), developed no external TIR symptoms, but about half of these tomatoes had internal TIR symptoms. About one-third of the tomatoes developed external symptoms during ripening, but these symptoms disappeared after ripening was complete. A high percentage (71%) of these tomatoes with external symptoms also had internal symptoms. The remaining tomatoes developed external TIR that did not disappear, and almost all of these tomatoes had internal symptoms. These data suggest that culling tomatoes that develop external TIR during ripening will reduce but not eliminate tomatoes with internal TIR from the fresh-fruit market.
Composts may improve crop growth in sandy soils. A biosolids-yard trimming compost (C) was incorporated into sandy soil at 134 t·ha–1 (49.7% moisture) before applying polyethylene mulch. Fertilizer (F) was applied at 0%, 50%, and 100% of the grower's rate (71N–39P–44K t·ha–1 broadcast and 283N–278K t·ha–1 banded in bed centers). `Elisa' pepper transplants were planted 20 Jan. 1994. Marketable fruit weights were 20, 31, and 32 t·ha–1 without C and 30, 35, and 32 t·ha–1 with C for 0%, 50%, and 100% F, respectively. Pepper fruit weights increased with increasing F rates and were higher in plots with C than without C. Without removing mulch, `Thunder' cucumbers were seeded on 26 Sept. 1994. Marketable fruit weights were similar at the three F levels, but were 23 and 27 t·ha–1 without and with C, respectively. One application of C significantly increased bell pepper yields and a subsequent cucumber crop.
Abstract
Three jointless tomato (Lycopersicon esculentum Mill.) cultivars, ‘MH-1’, ‘Hayslip’, and ‘Burgis’, were evaluated for fruit yields using a semi-mechanical freshmarket tomato harvester. Harvest dates were 85 or 99 days after transplanting in Fall 1980, and 88 or 95 days after transplanting in Fall 1982. Total fruit yields of the late harvest were significantly higher than the early harvest in 1982, but not in 1980. An increased percentage yield (weight basis) of colored fruit occurred during the late harvest in both trials. ‘Burgis’ and ‘Hayslip’ had significantly higher green fruit yields and lower ripe fruit yields than ‘MH-1’ in both years. Yields of semi-mechanically harvested fruit were reduced by an average of 25% and 47% when compared with manually harvested fruit yields during 1980 and 1982, respectively.
Abstract
Roots have several vital functions in crop plants, including providing anchorage, absorbing and conducting water and nutrients, providing a “sink” (and sometimes a storage location) for assimilates, and synthesizing certain phytohormones. Yet, the statement made by Weaver and Bruner in 1927 (5) remains true today: “The roots of plants are the least known, least understood, and least appreciated parts of the plant”. This lack of understanding can be attributed to the fact that roots are usually out of sight, and to the tedious and difficult nature of root studies in situ.
Abstract
Lodging may be defined as “the state of permanent displacement of stems from their upright position” (31). Diverse factors are known to bring about lodging. Plants may be inherently weak and susceptible to lodging due to such traits as a low stem lignin content (4, 49) or a small root system (31, 40, 45). Plants may be weakened due to damage by insects or pathogens (24, 31). Cultural practices can increase lodging through increased plant populations (13, 31, 54), high fertilization rates (31, 54), irrigation (31, 54), or damage from cultivation (18). Both stem lodging and root lodging may occur. In stem lodging, the plant bends over or breaks at any point along its stem. In root lodging, straight and intact stems lean over from the ground level due to a disturbed or an inherently weak root system (31).