Section 7
Chapter 6,009

Nutritional physiological evaluation of drought resistance of warm season forage species comparative studies on root development water and nutrient absorption of forage species at various soil moisture levels

Ogata, S.; Saneoka, H.; Matsumoto, K.

Grassland Science 31(3): 263-271


ISSN/ISBN: 1744-6961
Accession: 006008900

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In previous papers, we selected some warm season forage plants having a higher tolerance to the water stress (drought) condition. These plants were able to absorb nutrient and water effectively even under the water stress condition. The vigorous growth of root system and the water potential depression in leaves under the water stress condition were contributive to the water stress tolerance in plants. In this study, the water stress tolerance was further analyzed in relation to the changes of osmotic potential in various plant parts, root development and root pressure of rhodesgrass (Chloris gayana Kunth.), sorghum (Sorghum bicolor Moench) and job's tears (Coix lacryma jobi L. var. mayuen (Roman.) Stapf) grown under the water stress condition. The results obtained are as follows. (1) The osmotic potential in each species decreased by the water stress, especially remarkable in rhodesgrass. (2) Total root length and root surface area of rhodesgrass was five to six and three to four times as large as those of job's tears under the water stress condition, respectively. (3) The root development of job's tears was seriously inhibited by the water stress, but the penetration and development of rhodesgrass root was not depressed in deeper soil layer under the water stress condition. (4) The root pressure increased in rhodesgrass with the increase of water stress, but apparently decreased in job's tears. From the results obtained here, it was assumed that the high water and nutrient absorption abilities of grasses being tolerant to the water stress are depending on (1) their higher water absorption potentials resulted with decreasing osmotic potentials of their stems and leaves, (2) the vigorous growth of their roots into deeper soil layer, and also (3) the efficient movement of water and nutrient by increasing their root pressure under the less soil moisture condition.

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