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  • Author or Editor: M.B. Kirkham x
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Horticultural crops use a large amount of good quality water. For example, in the dry west of the United States, nearly one-half of the domestic water supply is applied to lawns and ornamental plants (42, 61). In order not to waste water, it should be applied only when the plants are under drought stress. To determine when supplemental irrigation is required, plant water status needs to be measured. The objective of this paper is to outline instruments now being used to measure the water status of plants. In particular, instruments that monitor water potential, osmotic potential, turgor potential, stomatal resistance (reciprocal of stomatal conductance), and canopy temperature are discussed. The advantages and disadvantages of these measurements are described. Previous reviews on instruments for plant-water studies include those by Barrs (2), Monteith (96), Slavik (136), Turner (159), Squire, Black, and Gregory (139), and Hanan (50). Plant-water measurements made on some specific horticultural crops have been detailed. These crops and the references are as follows: citrus (Fortunella, Poncirus, Citrus) (74), apple (Malus) (79), peach (Prunus) (26), grape (Vitis) (137), and small fruits [strawberry (Fragaria, blueberry (Vaccinium), raspberry (Rubus), cranberry (Vaccinium), gooseberry (Ribes), and currant (Ribes)] (35).

Open Access
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If wastewater is to be recycled safely for agricultural production the problems associated with using it on vegetables need to be known. The objective of this review is to determine those problems. Several earlier reviews dealing with the use of wastewater in agriculture have been published (5, 7, 9, 19, 27, 30, 31, 42). Raw wastewater, or primary effluent, is not considered in this paper because secondary effluent is the type of wastewater generally used for irrigation in the United States (42). Primary treatment involves only settling tanks, from which anything in the raw sewage that can float or sink is removed. Sewage from primary treatment is subjected in secondary treatment to the action of living microorganisms: e.g., activated-sludge processes, trickling filters, treatment ponds (42). Also, this paper is limited in discussion to municipal waste-water and does not mention wastewater from industry, including wastewater from vegetable-processing plants. This review is divided into 3 areas: physical, chemical, and biological problems.

Open Access
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Abstract

Chrysanthemum plants (Chrysanthemum morifolium Ramat. cv. Bright Golden Anne) were grown for 84 days in plastic pots containing 6 different media treated with inorganic fertilizers or liquid digested sewage sludge at 50, 100, and 200 ml/week. Plants grown in 1 soil: 1 sand: 1 peat, 1 soil: 1 sand, and 1 soil: 1 peat were similar to each other in size, and larger than plants grown in 1 sand:1 peat, all sand, or all peat. Peat-grown plants were smallest. Plant size and flower diameter decreased with increasing rates of sludge application. Plants fertilized with inorganic sources of fertilizer looked the same as those grown with 50 ml/week sludge (6 mm), except the sludge-treated plants were shorter and had a smaller dry weight. Plants treated with 50 ml/week sludge had flowers with a diameter and dry weight equal to those of flowers grown with liquid or pelletized inorganic fertilizer.

Open Access

Abstract

Water and turgor potentials of callus tissue from the cactus Echinopsis turbinata L. increased with increasing concentration of kinetin. Osmotic potential showed no consistent trend with an increase in concentration of kinetin or p-chlorophenoxyacetic acid (p-CPA).

Open Access

Growers have indicated that changes in soil quality under production in high tunnels is an important problem, but these have not yet been quantified or critically assessed in the central Great Plains of the United States. We conducted surveys of grower perceptions of soil quality in their tunnels (n = 81) and compared selected soil quality indicators (salinity and particulate organic matter carbon) under high tunnels of varying ages with those of adjacent fields at sites in Kansas, Missouri, Nebraska, and Iowa in the United States. Fourteen percent of growers surveyed considered soil quality to be a problem in their high tunnels, and there were significant correlations between grower perceptions of soil quality problems and reported observations of clod formation and surface crusting and to a lesser extent surface mineral deposition. Grower perception of soil quality and grower observation of soil characteristics were not related to high tunnel age. Soil surface salinity was elevated in some high tunnels compared with adjacent fields but was not related to time under the high tunnel. In the soil upper 5 cm, salinity in fields did not exceed 2 dS·m−1 and was less than 2 dS·m−1 under 74% of high tunnels and less than 4 dS·m−1 in 97% of high tunnels. The particulate organic matter carbon fraction was higher in high tunnels than adjacent fields at 73% of locations sampled. Particulate organic matter carbon measured 0.11 to 0.67 g particulate organic matter per g of the total carbon under high tunnels sampled. Particulate organic matter carbon in the soil was also not correlated to age of high tunnel. Soil quality as measured in this study was not negatively impacted by use of high tunnel structures over time.

Free access

The sustainability of soil quality under high tunnels will influence management of high tunnels currently in use and grower decisions regarding design and management of new high tunnels to be constructed. Soil quality was quantified using measures of soil pH, salinity, total carbon, and particulate organic matter (POM) carbon in a silt loam soil that had been in vegetable production under high tunnels at the research station in Olathe, KS, for eight years. Soil under high tunnels was compared with that in adjacent fields in both a conventional and an organic management system. The eight-year presence of high tunnels under the conventional management system resulted in increased soil pH and salinity but did not affect soil carbon. In the organic management system, high tunnels did not affect soil pH, increased soil salinity, and influenced soil carbon (C) pools with an increase in POM carbon. The increases in soil salinity were not enough to be detrimental to crops. These results indicate that soil quality was not adversely affected by eight years under stationary high tunnels managed with conventionally or organically produced vegetable crops.

Free access