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Title: RESPONSE OF LISIANTHUS TO IRRIGATION WITH SALINE WATER: ION RELATIONS

Author
item VALDEZ-AGUILAR, LUIS - Centro De Investigacion
item Grieve, Catherine
item Poss, James

Submitted to: Journal of Plant Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2011
Publication Date: 12/17/2013
Citation: Valdez-Aguilar, L.A., Grieve, C.M., Poss, J.A. 2013. RESPONSE OF LISIANTHUS TO IRRIGATION WITH SALINE WATER: ION RELATIONS. Journal of Plant Nutrition. 37(4):546-561. doi:10.1080/01904167.2013.867982.

Interpretive Summary: Competition among agricultural and urban users for high-quality water supplies has increased as the population increases. One environmentally-sound approach for conserving these dwindling water resources is the capture and reuse of degraded, often saline, wastewaters for crop production. Growers of high value cut flower crops have traditionally used high-quality waters in order to avoid jeopardizing quality and yield of the marketable product. This report is a companion paper to one (USSL #2357) describing the effect of saline waters on yield and quality of lisianthus, a highly valued bedding and cut flower crop. This paper describes plant uptake of mineral ions, their distribution within the plant, and the effect mineral ion relations may have on plant performance, Two lisianthus cultivars (‘Echo Blue’ and ‘Pure White’) were grown in greenhouse sand cultures and irrigated with recycled saline waters differing in ion composition. Water ‘A’ was prepared to simulate well waters in the coastal areas of California that are contaminated by sea water. Water ‘B’ mimicked saline tailwaters prevalent in the inland valleys of southern California and essentially represent concentrations of Colorado River water. Six salinity treatments of each water type were used. Electrical conductivities of the irrigation waters were 2, 4, 6, 8, 10, and 12 dS/m. Ion content of leaves of different ages was determined. The cultivars exhibited different adaptive responses to salinity stress. Sodium was retained in older leaves of ‘Echo Blue’ and excluded from the actively photosynthesizing young leaves, thus preventing leaf injury by this potentially toxic ion. Sodium was not strongly excluded from young leaves of ‘Pure White’. ‘Pure White’, on the other hand, was able to regulate accumulation of magnesium to a greater extent than ‘Echo Blue’. Differences in ion composition of the irrigation waters had small but significant effects on shoot ion concentrations. The ability of lisianthus to control the uptake and distribution of mineral ions may contribute to the tolerance of this species to moderate salinity. Research scientists and extension specialists will find this information valuable in managing salinity in recycled irrigation waters differing in ion composition.

Technical Abstract: Eustoma grandiflorum (Raf.) Shinn. (lisianthus) is a moderately salt tolerant species that can be produced commercially under irrigation with saline wastewaters prevalent in two salt-affected areas of California. The objective of the present studies was to determine the effect of irrigation with saline waters of two different compositions on the ion accumulation and ion relations of lisianthus ‘Pure White’ and ‘Echo Blue’. The ionic composition of irrigation waters simulated the compositions typical of (i) sea water dilutions (SWD) and (ii) concentrations of Colorado River water (CCRW). Electrical conductivities (EC) of SWD and CCRW were between 2 and 12 dS · m'1. Plants irrigated with CCRW were higher in Ca2+ compared to plants irrigated with SWD water. Calcium was also higher in ‘Pure White’ than in ‘Echo Blue’. Increasing EC of irrigation water caused a significant decrease in shoot and leaf Ca2+ concentration in ‘Echo Blue’, but had no effect on Ca2+ content of ‘Pure White’ shoots and leaves. Magnesium concentration in ‘Echo Blue’ was higher than in ‘Pure White’. Electrical conductivity did not significantly affect Mg2+ concentration of either cultivar, despite the increasingly higher external concentration. Potassium concentration of young and mature leaves of ‘Echo Blue’ increased as EC increased from 2 to 8 dS • m'1, then decreased significantly once EC exceeded 8 dS • m'1. Potassium concentration of ‘Pure White’ leaves decreased over the range of salinity treatments tested, suggesting that the reduced K+ activity at EC levels of 8 dS • m'1, or less, that resulted in lower leaf'K+ in ‘Pure White’ did not cause a decrease in K+ uptake in ‘Echo Blue’. Increases in external Na+ caused a significant increase in Na+ in ‘Pure White’ leaves and these plants exhibited the best growth even when levels of Na+ were high enough to be considered detrimental for growth.