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Donald R. Davis

knowledge. Citations to the review are diverse, involving (in descending order), grains, fruits and vegetables, trees and shrubs, legumes, pasture plants, and flowers. The most commonly cited fruits and vegetables are tomatoes, potatoes, taro, onions

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Rick A. Boydston, Harold P. Collins and Steven F. Vaughn

potential herbicidal activity is dried distiller grains with solubles (DDGS) which is commonly used as cattle feed. Developing new uses for DDGS could increase the overall profitability of ethanol produced from corn. DDGS typically consist of 10% moisture

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Bernard H. Zandstra and William R. Chase

Small grains are interseeded with several vegetable crops in Michigan to protect them from wind and water erosion. When the vegetable crop is well-established, the small grain is killed with a graminicide. Research was conducted to determine the optimum combination of small grain species, age of kill, and nitrogen application rate for acceptable pickling cucumber yield in a single harvest. In several experiments, barley, oats, rye, and wheat were seeded at 130 seeds/m2 in the field. Cucumbers were seeded 1 week later. The cover crops were treated with sethoxydim at 0.21 or 0.31 kg·ha–1 plus 1.25% COC when they were 7 to 10 or 13 to 16 cm tall. Small grain size at application had no effect on their kill with sethoxydim or on cucumber yields. Barley and rye were the most vigorous small grains up to 3 weeks after seeding, but oats were similar in size by 4 weeks. Wheat was slower to develop, and more difficult to kill with sethoxydim. The optimum nitrogen treatment was 34 kg·ha–1 before planting the cover crop, followed by 45 kg·ha–1 at the two- to three-leaf stage of cucumber.

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Jules Janick

World crops with particular relevance to horticulture. Table 1. Selected crops indigenous to the New World. NEW WORLD CROPS Grains and pseudograins Various grains and pseudograins were domesticated in the New World, including maize ( Zea mays ), amaranth

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Margaret J. Makinde and Adenike O. Olufolaji

Having established that the white-seeded amaranth (grain amaranth) can supply both green leaves and seeds (grains) for the Nigerian consumers, there was a need to find cultivars that could yield enough grains to be profitable for an amaranth farmer. Several lines (>100) were screened, with the opaque and creamy-colored seed as the ultimate target. These cultivars, NHAm 261-1 and NHAm258, were selected for yield trials. It was possible to have a high seed rate of 100 plants/m2, and thinning to 22 plants/m2 at the end of 6 weeks. These 22 plants were left to mature, and a maximum of 20 plants/m 2 were evaluated for grain yield. These two cultivars were found to give good fresh shoot yields as well as capacity for up to 3000/m2.

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Bernard H. Zandstra, William R. Chase and Joseph G. Masabni

Pickling cucumbers (Cucumis sativus L.) for machine harvest were interplanted with barley (Hordeum vulgare L.), oat (Avena sativa L.), rye (Secale cereale L.), sorghum-sudan (Sorghum vulgare L.), or wheat (Triticum aestivum L.). Cover crops 3 to 5 (7.6 to 12.7 cm) or 6 to 10 inches (15.2 to 25.4 cm) tall were killed with sethoxydim. Cover crops seeded at ≈12 seeds/ft2 (129 seeds/m2) provided protection from wind erosion and minimal crop competition. Additional nitrogen to obtain maximum yield was required when small grain cover crops were interplanted with cucumbers. Barley emerged rapidly, grew upright, and was killed easily with sethoxydim, making it ideal for interplanting. All cover crops caused some cucumber yield reduction under adverse growing conditions.

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Vikramjit S. Bajwa* and Curt Rom

Osmotic agents used to prevent apple pollen grain germination were studied in vitro by applying 10 μL of solutions to germinating apple pollen on germinating and growth media. Seven concentrations (0%, 0.25%, 0.5%, 1%, 2%, 5% and 10%) of the solution were prepared for each chemical and the characteristics of pH, EC, and osmotic potential were measured. Apple pollen was dispersed onto the media in petri dishes. Micro drops of solution were then applied to marked areas. Dishes were then placed in germination cabinets at 25 °C. Cumulative percentage pollen germination was calculated 4, 8, 12, and 24 h after treatment by microscopic observation. Generally, the cumulative percentage pollen germination decreased asymptotically with increasing chemical concentration. The most effective chemicals for restricting pollen germination and growth were CuSO4 (0.25%), CH3 COOH (0.25%), CaCl2 (10%), K2 S2 O5 (0.25%), Methyl Jasmonate (2%). The effect of these chemicals has also been tested on pistil viability both in vitro and on excised limbs.

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Michael S. Stanghellini and Jonathan R. Schultheis

In 1999 and 2000, a total of 27 diploid watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] cultivars and advanced breeding lines (hereafter referred to as cultigens) were evaluated for staminate flower and pollen grain production to assess their potential to serve as pollenizers (pollen source plants) in triploid watermelon production systems. Male reproductive output (staminate flower and pollen production) was quantified during the peak flowering and fruit setting phase of the cultigens under field conditions. The number of staminate flowers produced per plant per day, number of pollen grains produced per flower, and total number of pollen grains produced per plant per day (staminate flowers per plant × pollen grains produced per flower) differed greatly among cultigens (for all tests, P < 0.01). Staminate flower production by cultigens differed by year (P < 0.0029) and days within years (P = 0.0225), but pollen production between years by cultigens was stable (P = 0.4841). Total male reproductive output ranged from 134,206 pollen grains per plant per day for `Jamboree' to 321,905 pollen grains per plant per day for `Summer Flavor 500'. These studies demonstrate the genotypic variability in watermelon male reproductive output potential, and may assist growers in choosing a good diploid pollenizer for triploid watermelon production.

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Jian Fang, E.E. Roos, C.T. Walters and F.D. Moore III

Seed hydration and dehydration affects many physiological reactions, including priming, accelerated aging, and desiccation intolerance. Maize grains were repeatedly imbibed and desiccated, or imbibed and held for periods of time to identify the role of each of these factors. Grains were equilibrated to 12% moisture content (mc) and subjected to cycles (up to 14) of hydration (2 hours) and immediate dryback, or one hydration of 2 to 12 hours and dryback. Germination and vigor (root length and leachate conductivity) were determined after each cycle. Grains adjusted to three levels of hydration (27%, 34%, and 40%) were held for up to 10 days in a sealed desiccator. Each day samples were taken and either dried to the original mc prior to evaluation, or evaluated immediately as above. With each cycle of 2 hours of imbibition, seed mc increased (22% to 39%). Root lengths increased (priming effect) during the early cycles of imbibition and dryback. Decline in germination after eight cycles was a result of either accelerated aging or desiccation intolerance. Based on the results of the holding study, both factors contributed to deterioration, but desiccation intolerance was only observed when mc was above 27%. Conductivity of grain leachates was not correlated with loss of germination or vigor in whole grains, but appeared to reflect deterioration in isolated embryos.

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Ghodratollah Riazi, Shahrokh Khanizadeh and Majid Rahemi

The xenial and metaxenial effects of five different male sources on cross pollination of three pistachio cultivars, were studied in 1990 and 1991 in Rafsanjan/Iran. The pollen grains used were P. atlantica Desf., P. mutica F.& M., P. vera L. (Momtaz), P. vera L. (Soltani), and an open pollination. The female cultivars chosen were `Owhadi', `Kalleh-ghuchi', and `Momtaz', which occupy the largest cultivation area. Experiment was done in two successive years in a completely randomized design. Results of this study agreed with previous studies regarding the retardance of pistachio nut development by wild pollen species rather than P. vera L. The greatest change in various characteristics of nuts, e.g., kernel weight and shell splitting, occurred when P. mutica F.& M. pollen grains used followed by P. atlantica Desf. pollen grains. Thus, some manifestations of xenia and metaxenia could be inferred. In general, larger kernels and increased shell dehiscence resulted from the use of P. vera L. pollen grains. Greater kernel weight of `Kalleh-ghuchi', higher shell splitting of `Momtaz', and higher blank of `Owhadi' produced by pollination with P. vera L. in some extent could also be cultivar characteristics.