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- Author or Editor: Peter J. Stoffella x
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.
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.
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.
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.
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).
Rapid production of compost often results in crop damage by phytotoxic compounds or high C/N ratios in immature (uncured) compost. The influence of immature biosolids-yard trimmings compost on germination and growth of cucumber (Cucumis sativus L.) was evaluated. Germination percentages of cucumbers seeded in equal parts (v/v) of compost and vermiculite were similar to those in vermiculite. When screened compost was placed in flats and compared with flats of potting mix or sandy field soil, germination percentages were 98, 96, and 89 for mix, sand, and compost respectively. Germination in compost-amended field plots was higher than in soil when cucumbers were planted 1, 2 or 10 weeks after compost application, but similar in 3 and 5 week plantings. Use of this immature compost increased, decreased, or did not affect cucumber seed germination, depending on media and growing conditions.
Field experiments were conducted in 1985 at Fort Pierce, Fla., and Bixby, Okla., to quantify and describe the distribution of nodules among root morphological components of cowpea [Vigna unguiculata (L.) Walp.]. Plants of `Knuckle Purplehull', `Mississippi Cream', and `White Acre' were sampled by cultivar on separate dates at three growth stages: pre-anthesis, seed initiation, and harvest, when most pods were dry. Root masses were partitioned into adventitious, basal, lateral, and taproot components. Nodules were removed from roots, grouped according to root morphological component of origin, and weighed. No linear correlation was found between the weight of a particular root morphological component and the nodule weight associated with that component. Total root weight and total nodule weight also were not strongly correlated. Nodule weights usually were lower at harvest than at earlier stages of ontogeny, especially for nodules from taproots. Although ≈70% of the root mass was in the taproot and its associated laterals at both locations, the taproot per se was not the primary locus of nodulation. Instead, most nodules generally were located on the basal and lateral roots. When percentage distribution of total nodule weight was examined, neither growth stage nor cultivar was found to affect nodulation of basal or lateral roots.
Cabbage [Brassica oleracea L. (Capitata Group) cv. Bravo] transplants were grown on raised beds at Fort Pierce, Fla., during Fall 1987 and 1988. Plants were spaced at 8, 15, 23, 30, and 38 cm within rows or populations equivalent to 123,000, 61,500, 41,000, 30,800, and 24,600 plants/ha. Individual root weights, total plant weights, and core length increased linearly as within-row spacing (WRS) increased in both experiments. Untrimmed head weights, trimmed head weights, head height, head width, and core width increased quadratically as WRS increased in both experiments. Head shape and core index did not differ among WRS in either experiment, except for a quadratic increase in the head height: bead width ratio (head shape) as WRS increased in the 1988 experiment. Coefficients of variability (cv) for most measured variables decreased as WRS increased, indicating a reduction in plant-to-plant variation. Optimum marketable cabbage head size (>1 kg) and lower plant-to-plant variation (cv < 20%) were obtained at WRS of 23 cm or wider. However, trimmed cabbage yields decreased linearly as WRS increased in both experiments. In this study, a lower plant population (WRS > 23 cm) was more conducive to a once-over cabbage harvest since plant-to-plant variation in head size and other yield and quality characteristics was reduced.
Seeds of `Rutgers California Supreme' tomato (Lycopersicon esculentum Mill.) were exposed to outer space conditions aboard the long duration exposure facility (LDEF) satellite in the space exposed experiment developed for students (SEEDS) project of the National Aeronautics and Space Administration (NASA). Seeds aboard the LDEF were packed in dacron bags forming four layers per sealed canister. Some of these seeds were used in Oklahoma and Florida for studies of germination, emergence, and fruit yield. Among all measured variables in three experiments, there was only one significant main effect of canister 2 versus canister 7 (for mean time to germination) and only one main effect of layer (for seedling shoot dry weight). There also were only two inconsistent canister x layer interactions in the germination tests. The contrast of Earth-based control seed versus space-exposed seed was significant four times: in Oklahoma in 1991 the mean time to germination of space-exposed seeds and the days to 50% of final germination were 0.7 days less than for Earth-based seeds, and in Florida in 1992 seedling percent emergence and shoot dry weight were increased by space exposure. Fruit yield and marketability were unaffected in plants grown from space-exposed seeds. These results support student findings from the SEEDS project, and provide evidence that tomato seeds can survive in space for several years without adverse effects on germination, emergence, and fruit yield.