Response of Matthiola incana to irrigation with saline wastewaters

Two cultivars of Matthiola incana (L.) R. Br. ('Cheerful White' and 'Frolic Carmine') were grown in greenhouse sand cultures to determine the effect of salt stress on growth, ion relations, and flower quality. Two types of irrigation waters, differing in ion composition, were prepared to simulate saline wastewaters commonly present in two inland valley locations in California. Solution ICV was typical of saline tailwaters frequently found in the Imperial and Coachella Valleys and contained Cl(-), Na(+), SO4(2-), Mg(2+), Ca(2+), predominating in that order. Solution SJV was dominated by Na(+) and SO4(2-) and simulated saline drainage effluents often present in the San Joaquin Valley. Five treatments of each salinity type were imposed; each was replicated three times. Electrical conductivities of the irrigation waters (EC(i)) were 2.5, 5, 8, 11, and 14 dS.m(-1). Plant heights were determined weekly. Seedlings were sampled for ion analysis 9 weeks after planting. Flowering stems were harvested when about 50% of the florets in the inflorescence were open. Total stem length, weight and diameter, numbers of florets and buds, and inflorescence length were measured at final harvest. All plants remained healthy throughout the experimental period with no visible signs of ion toxicity or deficiency. Although length of the flowering stems decreased with increasing salinity, stems were of marketable quality even at the highest salinity level. Mineral ion composition of the vegetative tissues generally reflected ion concentrations in the irrigation waters. Shoot Mg(2+) and Cl(-) were higher and shoot Na(+) lower in seedlings irrigated with ICV waters than with SJV waters. Shoot P was reduced over control levels once salinity exceeded 11 dS.m(-1). Both cultivars were highly selective for K(+) over Na(+) and selectivity coefficients (S(K, Na)) increase about 60% as salinity increased from 2.5 to 14 dS.m(-1). This study illustrates that commercially acceptable cut flowers of stock may be produced under irrigation with moderately saline wastewaters.