Interaction between Light Intensity and NaCl Salinity and Their Effects on Growth, CO(2) Assimilation, and Photosynthate Conversion in Young Broad Beans

Effects of different salt sources and salinity levels on emergence and seedling growth of faba bean genotypes

Suitability of poor quality water for irrigation depends on salinity level and solute concentration in the water and selected crop. Salt stress is a major potential constraint for faba bean. The present study aimed to investigate the effects of different Cl- and SO₄-containing salt sources in irrigation water with different salinity levels on emergence, early seedling growth and photosynthetic capacity of six faba bean genotypes. The negative effect order of salinity level was high (3 dS/m) > medium (2 dS/m) > low (1 dS/m) > control (0.05 dS/m) for all investigated parameters except dry root weight. The negative effects of Cl-containing salt sources were higher than that of SO₄-containing salt sources. The worst and the best performing genotypes were determined as III-28 and III-29 on emergence percentage at 10th DAS, I-29 and III-1 on mean emergence time, III-22 and III-1 on shoot height, III-1 and I-29 on fresh biomass weight, III-22 and III-28 on fresh shoot weight, III-29 and I-29 on fresh root weight, respectively. This study showed that faba bean genotypes have different behaviors in terms of response to the increasing salinity levels artificially makeup by using different salt sources indicating that salt response of faba bean is genotype-specific.

Container-grown tree seedling responses to sodium chloride applications in different substrates

Seedlings of Norway maple (Acer platanoides), silver birch (Betula pendula), Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) were grown in selected sodium chloride (NaCl) concentrations, soil types and under different watering regimes. Plants were raised from seeds, except for Scots pine plants which were obtained from a commercial source. Among the plant species tested, Scots pine was the most tolerant to soil salinity, while Norway spruce was the most susceptible. For both Norway maple and Norway spruce some half-sib families were more tolerant than others. No significant correlation was found between the tolerance of different half-sib families and the tolerance of mother trees observed in the field. The extent of leaf necrosis correlated significantly with the leaf concentrations of sodium (Na) and chloride (Cl). Among half-sib families within the species no such correlation was found. On the other hand, the least injured progeny of Norway maples had the highest concentrations of NaCl. The extent of salt-induced leaf necrosis varied with soil type, and a significant interaction between species and soil type was observed. Seedlings of Norway spruce grown in sand showed more severe necrosis and significantly higher concentrations of Na and Cl than seedlings grown in loam, silt loam, and peat. The severity of salt-induced leaf injury varied with the watering regime. Silver birch was the most affected species by drought and autumn watering treatments. Plants of silver birch subjected to drought showed increased leaf necrosis compared to the non-treated plants, and autumn watering treatment reduced the severity of leaf necrosis.

Salinity Effects on Photosynthesis and Growth in Alternanthera philoxeroides (Mart.) Griseb

Alternanthera philoxeroides, alligator weed, was grown at five different NaCl concentrations to determine the effect of salinity on factors related to the net rate of CO(2) uptake (P(n)). Over the range of 0 to 400 millimolar NaCl, P(n) declined 51%. Stomatal conductance declined in parallel with P(n) and as a result there was no reduction in intercellular CO(2) concentration and therefore no reduction in the amount of CO(2) available for photosynthesis. The CO(2) compensation point did not change with salt stress. Increases in leaf thickness tended to compensate slightly for the negative effects of salinity on leaf cell metabolism, at least in relation to P(n). On a mesophyll cell area basis, soluble protein was relatively constant in leaves developed at 100 to 400 millimolar NaCl while total chlorophyll decreased at all salinities. Dry weight production and P(n) were closely correlated in alligator weed grown at different salinities. Plants produced less leaf area per unit dry weight as salinity increased, which may aid in water conservation.