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Abstract
Many researchers have discussed the need for precision planting in research plots and have designed new or have modified existing planters to fit their needs. Commercially available precision planters are very expensive and are best suited to planting small, round, or coated seeds, but are less adapted to large irregularly shaped seeds. Inexpensive planter mechanisms have been adapted for precision planting by various modifications (1, 4, 5). However, these planters were either hand-pushed, or failed to provide for wide seed spacing in the row.
Abstract
Response of celery (Apium graveolens L.) to soil acidification and foliar Mn application was evaluated in a field experiment on a Histosol of near-neutral pH. Acid sources varied in their effectiveness in reducing pH when broadcast at 1120 and 2240 kg·ha−1 or band-applied at ≈200 kg·a−1. Broadcast application increased yield compared to the control or band treatments, but band application of a granular S and Mn product proved superior to the other band treatments. Soil and foliar treatment interaction data showed that the strategies were substitutionary. Foliar Mn application is more economical than soil acidification but soil acidification, especially by band application of a low rate of S and Mn together, also may prove cost-effective.
Vegetable gardening in The Gambia provides an important supplemental income for women farmers who grow tomato, onion, cabbage and other vegetables for sale on the local market, to restaurants and for export to Europe. Government and international agencies provide research and technical support, while non-governmental organizations (NGO's) provide production capital (such as wells) and marketing support. Production problems include pest management and the labor intensity of hand irrigation and harvesting. Growers cite low prices as their greatest constraint. Small local canning facilities may help alleviate market gluts and extend marketing and consumption opportunities beyond the fresh market production season.
Pre- and posttransplant growth of plug seedlings is affected by the nutrition of the plants. The effects of weekly applications of nutrient solution with different N (8—32 mM) or P and K (0.25—1.0 mM) levels on the growth and nutrient composition of impatiens (Impatiens wallerana Hook. f.) and petunia (Petunia ×hybrida hort. Vilm.-Andr.) plug seedlings were quantified. Impatiens and petunia pretransplant seedling growth was most rapid with a NO3 - concentration of 24 or 32 mM (N at 336 and 448 mg·L-1), while P and K had little effect. Increasing the N concentration in the fertilizer also increased shoot tissue N levels of both impatiens and petunia and decreased shoot P level of impatiens and K level of petunia. Posttransplant growth was most rapid in plants that received N at 16 to 32 mM. Decreasing P and K from 1 to 0.25 mM in the pretransplant fertilizer reduced posttransplant growth. Shoot P level of impatiens 15 d after transplanting decreased from 6.9 to 4.8 mg·g-1 as the pretransplant fertilizer N concentration increased from 8 to 32 mM, while N level increased from 18 to 28 mg·g-1 as P and K fertilizer concentrations increased from 0.25 to 1 mM. Using posttransplant growth as a quantitative norm for plug quality, the sufficiency ranges for tissue N level are 28 to 40 mg·g-1 for impatiens and 30 to 43 mg·g-1 for petunia plugs. These results indicate that fertilization programs for high-quality plug production should focus on N nutrition, and that plugs can be grown with greatly reduced levels of P and K.
Good fertilizer management is important in plug seedling production of bedding plants to prevent nutrient deficiencies and toxicities. We determined the effect of N, P, and K nutrition on the growth of plugs of impatiens (Impatiens wallerana Hook. f.), petunia (Petunia ×hybrida Hort. Vilm.-Andr.), salvia (Salvia splendens F. Sellow ex Roem.& Schult.), and vinca (Catharanthus roseus L.). For all four species, shoot N concentration was correlated linearly with shoot dry mass of the seedlings at transplant. Phosphorus or K concentration in the nutrient solution or shoot tissue had little or no effect on the shoot growth of seedlings, but shoot P levels increased with P concentrations in the fertilizer solution (luxury consumption). Salvia was the only species that also exhibited luxury consumption of K. Results of this study indicate that seedling growth of these species is mainly determined by N and this should probably be the main focus of fertility programs in the plug industry, while P and K applications can be reduced.
Pre- and posttransplant growth of plug seedlings is affected by the nutrition of the plants. The effects of weekly applications of nutrient solution with different N (8-32 mm) or P and K (0.25-1.0 mm) levels on the growth and nutrient composition of impatiens (Impatiens wallerana Hook. f.) and petunia (Petunia ×hybrida hort. Vilm.-Andr.) plug seedlings were quantified. Impatiens and petunia pretransplant seedling growth was most rapid with a
Abstract
Reference values were derived from field data for use in evaluating the N, P, K, Ca, and Mg status of ‘Valencia’ orange (Citrus sinensis [L.] Osbeck) trees by the Diagnosis and Recommendation Integrated System (DRIS). DRIS diagnoses generally agreed with diagnoses made by the sufficiency range method, with the advantage that DRIS reflects nutrient balance, and identifies the order in which nutrients are likely to become limiting. DRIS diagnoses were affected by the type and age of the tissue sampled. DRIS reflected changes in nutrient concentrations due to alternate bearing or crop load effects and agreed with the sufficiency range method when concentration changes were sufficient to affect the latter method.
Pesticides have been the primary method of pest control for years, and growers depend on them to control insect and disease-causing pests effectively and economically. However, opportunities for reducing the potential pollution arising from the use of pesticides and fertilizers in environmental horticulture are excellent. Greenhouse, nursery, and sod producers are using many of the scouting and cultural practices recommended for reducing the outbreak potential and severity of disease and insect problems. Growers are receptive to alternatives to conventional pesticides, and many already use biorational insecticides. Future research should focus on increasing the effectiveness and availability of these alternatives. Optimizing growing conditions, and thereby plant health, reduces the susceptibility of plants to many disease and insect pest problems. Impediments to reducing the use of conventional pesticides and fertilizers in the environmental horticulture industry include 1) lack of easily implemented, reliable, and cost-effective alternative pest control methods; 2) inadequate funding for research to develop alternatives; 3) lack of sufficient educational or resource information for users on the availability of alternatives; 4) insufficient funding for educating users on implementing alternatives; 5) lack of economic or regulatory incentive for growers to implement alternatives; and 6) limited consumer acceptance of aesthetic damage to plants. Research and broadly defined educational efforts will help alleviate these impediments to reducing potential pollution by the environmental horticulture industry.