No abstract

Salinity is a problem for crop production worldwide and may be particularly problematic for ornamental plants because it has the potential to degrade visual quality. Daffodils [Narcissus sp. (L.) Amaryllidaceae] are a popular bulb plant, in demand for both landscapes and cut flowers. In this study, we examined how salinities ranging from 0 to 300 mm NaCl affected growth, flower production, and leaf physiology of three of the most popular cultivars of daffodil (‘Dutch Master’, ‘Ice Follies’, and ‘Tete-a-Tete’). Salinity reduced growth rate and biomass production at salinities greater than or equal to 100 mm NaCl with the greatest reductions in the highest salinity treatments (200 and 300 mm NaCl). Despite reductions in biomass, there was no significant chlorosis of the leaves. Flower quantity was unaffected by salinity in ‘Dutch Master’ and ‘Ice Follies’, but anthesis was delayed and flower duration was reduced by 40% to 70% at salinities of 150 mm NaCl and above. Anthesis and flower duration in ‘Tete-a-Tete’ were unaffected by salinity, but the number of flowers produced was negatively affected (reductions of 50% or more) by salinities of 150 mm NaCl and above. Sodium concentration in the leaves and bulbs increased 53% to 400% compared with the 0 mm NaCl control with lower accumulation in the bulbs than in the shoots. Sodium accumulation occurred at or above 50 mm NaCl in ‘Tete-a-Tete’, but at salinities greater than 150 mm NaCl in ‘Dutch Master’ and only in the 300-mm NaCl treatment in ‘Ice Follies’. Despite the Na+ accumulation in the leaves, the plants in most of the salinity treatments were able to maintain a K+:Na+ ratio above 1 (except in ‘Tete-a-Tete’ at salinities 150 mm NaCl or greater), which may have helped the daffodils tolerate the negative affects of Na+ and maintain good visual quality. ‘Dutch Master’, ‘Tete-a-Tete’, and ‘Ice Follies’ can be considered highly salt-tolerant because they maintain visual quality (leaf greenness, flower production, and flower duration) at soil NaCl-induced electrical conductivities greater than 6 dS·m−1.

No abstract

Evolutionary divergence among disjunct populations that encounter 18 different stressful conditions may be rapid due to limited gene flow. Arabidopsis 19 lyrata ssp. lyrata (L.) O'Kane & Al-Shehbaz grows throughout the mid-Atlantic region in 20 a variety of fragmented and stressful environments, including serpentine soils. The 21 purpose of this study was to investigate the differential responses to heavy metals 22 (particularly nickel and chromium, naturally occurring in serpentine soils) among three 23 serpentine populations compared to two non-serpentine populations of A. l. ssp. lyrata, as 24 evidence of local adaptation. The five populations were exposed to a nickel, chromium 25 or control treatment during germination and juvenile growth. None of the populations 26 had a negative growth response to chromium. All five populations had reductions in 27

Species with widespread distributions that grow in varied habitats may consist of ecotypes adapted to a particular habitat, or may exhibit cross-tolerance that enables them to exploit a variety of habitats. Populations of Arabidopsis lyrata ssp. lyrata (L.) O’Kane & Al-Shehbaz grow in a wide variety of edaphic settings including serpentine soil, limestone sand, and alluvial flood plains. While all three of these environments share some stressors, a crucial difference among these environments is soil calcium to magnesium ratio, which ranges from 25∶1 in the limestone sand to 0.2∶1 in serpentine soil. The three populations found on these substrates were subjected to three different Ca to Mg ratios under controlled environmental conditions during germination and rosette growth. Response to Ca to Mg ratio was evaluated through germination success and radicle growth rate, rosette growth rate, and the content of Ca and Mg in the rosette. All three populations were particularly efficient in fueling growth under nutrient deficiency, with the highest nutrient efficiency ratio for Ca under Ca deficiency and for Mg under Mg deficiency. Although the serpentine population had significantly higher leaf Ca to Mg ratio than the limestone or flood plain populations under all three Ca to Mg ratios, this increase did not result in any advantage in growth or appearance of the serpentine plants, during early life stages before the onset of flowering, even in the high Mg substrate. The three populations showed no population by substrate interaction for any of the parameters measured indicating that these populations may have cross-tolerance to substrate Ca to Mg ratio.