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Geungjoo Lee, Robert N. Carrow, and Ronny R. Duncan

Seashore paspalum (Paspalum vaginatum Swartz) is a warm season turfgrass that survives in sand dunes along coastal sites and around brackish ponds or estuaries. The first exposure to salt stress normally occurs in the rhizosphere for persistent turfgrass. Information on diversity in salinity tolerance of seashore paspalums is limited. From Apr. to Oct. 1997, eight seashore paspalum ecotypes (SI 94-1, SI 92, SI 94-2, `Sea Isle 1', `Excalibur', `Sea Isle 2000', `Salam', `Adalayd') and four bermudagrass (Cynodon dactylon × C. transvaalensis Butt-Davy) cultivars (`Tifgreen', `Tifway', `TifSport', `TifEagle') were investigated for levels of salinity tolerance based on root and verdure responses in nutrient/sand culture under greenhouse conditions. Different salt levels (1.1 to 41.1 dS·m-1) were created with sea salt. Measurements were taken for absolute growth at 1.1 (ECw0; electrical conductivity of water), 24.8 (ECw24), 33.1 (ECw 32), and 41.1 dS·m-1 (ECw40), threshold ECw, and ECw for 25% growth reduction from ECw0 growth (ECw25%). Varying levels of salinity tolerance among the 12 entries were observed based on root, verdure, and total plant yield. Ranges of root characteristics were inherent growth (ECw0) = 0.20 to 0.61 g dry weight (DW); growth at ECw24 = 0.11 to 0.47 g; growth at ECw32 = 0.13 to 0.50 g; growth at ECw40 = 0.13 to 0.50 g; threshold ECw = 3.1 to 9.9 dS·m-1; and ECw25% = 23 to 39 dS·m-1. For verdure, ranges were inherent growth at ECw0 = 0.40 to 1.07 g DW; growth at ECw40 = 0.31 to 0.84 g; and ratio of yields at ECw40 to ECw0 = 0.54 to 1.03. Ranges for total growth were inherent growth at ECw0 = 0.72 to 2.66 g DW; growth at ECw24 = 0.55 to 2.23 g; growth at ECw32 = 0.54 to 2.08 g; growth at ECw40 = 0.52 to 1.66 g; threshold ECw = 2.3 to 12.8 dS·m-1; and ECw25% = 16 to 38 dS·m-1. Significant salinity tolerance differences existed among seashore paspalums and bermudagrasses as demonstrated by root, verdure, and total growth measurements. When grasses were ranked across all criteria exhibiting a significant F test based on root, verdure, and total growth, the most tolerant ecotypes were SI 94-1 and SI 92. Salinity tolerance of bermudagrass cultivars was relatively lower than SI 94-1 and SI 92. For assessing salinity tolerance, minimum evaluation criteria must include absolute growth at ECw0 and ECw 40 dS·m-1 for halophytes, but using all significant parameters of root and total yield is recommended for comprehensive evaluation.

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Touria El-Jaoual

diseases. The book investigates and reviews the biological approaches for controlling plant pathogens using predators, antagonistic microbes, rhizosphere microflora, or genetic engineering. It covers the principles, concepts, mechanisms, and current

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Xiaojie Zhao, Guihong Bi, Richard L. Harkess, and Eugene K. Blythe

Hyatt, 2010 ). The process of up taking NH 4 + or NO 3 − has a strong impact on the uptake of other cations and anions and rhizosphere pH. When roots take up NO 3 − , which has a negative charge, and NH 4 + , which has a positive charge, they typically

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Allen V. Barker

discussed to include various biochemical and molecular (genetic) regulations. Chapter 4 is “Plant Natural Products in the Rhizosphere.” It deals with collection and processing of plant exudates, degradation of products by microorganisms in the rhizosphere

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Fengyun Zhao, Yu Jiang, Xiufeng He, Huaifeng Liu, and Kun Yu

below the drip irrigation tape. The drip fertilization time and field management for all five treatments during the growing season were the same as that used for conventional planting. Table 1. Fertilization scheme. Testing parameters The rhizosphere

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Na Liu, Baoli Zhou, Xin Zhao, Bo Lu, Yixiu Li, and Jing Hao

typically enhanced by stress conditions that the plant encounters ( Pramanik et al., 2000 ). Root exudates also represent one of the largest direct inputs of plant chemicals into the rhizosphere environment ( Bertin et al., 2003 ). Allelochemicals in root

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Xiuling Tian and Youbin Zheng

Phytophthora infestans ( Ketterer, 1990 ). In the present study, Trichoderma spp. were among the main filamentous fungi isolated from the compost teas. T. harzianum , a filamentous fungus that is commonly found in the rhizosphere, was accepted as one of the

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Valérie Gravel, Martine Dorais, and Claudine Ménard

demonstrated that growing medium and rhizosphere bacterial communities were affected by different organic amendments applied to seedlings, which could explain, at least in part, the difference in plant growth after transplanting ( Jack et al., 2011 ). Organic

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Wenjing Guan, Xin Zhao, Richard Hassell, and Judy Thies

enhance our understanding of disease resistance of grafted vegetables. Shift of Rhizosphere Microbial Diversity as a Result of Grafting Rhizosphere microorganisms can play critical roles in suppressing soilborne diseases through a variety of mechanisms

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Lantian Du, Baojian Huang, Nanshan Du, Shirong Guo, Sheng Shu, and Jin Sun

soilborne diseases and pests. Singh et al. (1999) suggested that each crop exhibits unique microbial community characteristics in the rhizosphere. Long-term continuous cropping inevitably leads to the enrichment of soil microbes with a high parasitic