Germination, Mineral Composition, and Ion Uptake in Walnut Under Salinity Conditions

Abstract

<jats:p>Walnut (<jats:italic>J. regia</jats:italic> L.) is one of the most sensitive plants to abiotic stresses for which finding salt-tolerant genetic resources is very important. Effects of salt stress on seed germination of seven walnut cultivars (Serr, Lara, Pedro, Chandler, Hartely, Vina, and Roun de Montignac) were studied. Salt stress treatments were applied using NaCl solutions ranging from 50 to 250 m<jats:sc>m</jats:sc>. The increase in salinity levels resulted in a substantial decrease in root relative water content. The percent of germination was also affected by salinity level and cultivar and their interactions. The mean germination time differed among treatment media and cultivars and a significant interaction was observed between these two factors. According to the cluster analysis, ‘Chandler’ was classified as the most tolerant cultivar. ‘Hartley’, ‘Pedro’, and ‘Round de Montignac’ (‘RDM’) were also classified in another group (semisensitive), whereas ‘Vina’, ‘Serr’, and ‘Lara’ were classified as sensitive cultivars. With the increase in salt stress, resistant cultivars accumulated more potassium (K) and calcium, especially in their shoots. However, in the semitolerant cultivars, accumulation of K in the root was more than in the shoot. Differences in magnesium accumulation in roots and shoots of all samples were significant at all stress levels and were dependent on genotypes. Sodium levels in roots were higher than in the shoots in most cultivars, especially in the semisensitive and tolerant ones. There was a low correlation (<jats:italic>r</jats:italic><jats:sup>2</jats:sup> ≤ 0.15) between walnut seed traits (seed weight and kernel weight) and growth indices with respect to salinity tolerance.</jats:p>

Abiotic Stress Tolerance in Plants with Emphasizing on Drought and Salinity Stresses in Walnut

“…Decreasing the water potential to -1.0 MPa reduced the germination of all varieties to less than 50% and at -1.50 MPa, the germination decreased to less than 25% [192]. The drought and salt stress treatments were unaffected by the size of seeds or seed weight and there was not a significant correlation between percent germination and either seed or kernel weight [212]. Seedlings of walnut cultivars showed differential responses to salt stress under greenhouse conditions.…”

“…The mean germination time differed both among different treatments and cultivars and also a significant interaction was found between these two factors under salt stress condition [212]. For all the seedlings of walnut cultivars studied, the mean germination time was shorter in the control than in the other treatments [212].…”

“…Seed germination rates were generally more rapid in control (no salt stress) than in salt containing media. The FGP (final germination percentage) values were significantly lower at higher salinity levels and there were also differences in FGP among species [212].…”

“…Seedlings of 'Lara' and 'Chandler' were most and least affected by salt stress, respectively. The increase in salinity levels was accompanied by a substantial decrease in root RWC (relative water content) [212]. Seed germination rates were generally more rapid in control (no salt stress) than in salt containing media.…”

Multiple transcriptional regulation of walnut JrGSTTau1 gene in response to osmotic stress

“…So, ensuring walnut production and quality is important, which requires selection of suitable varieties that thrive in adverse environments. The key is to understand the adaptation mechanisms that walnut trees employ to overcome the unfavorable conditions (Lotfi et al , Naser et al , Aslamarz et al , Xu et al ). However, at present, the reports on J. regia mainly focus on walnut quality and product utilization, very few reports concerning the mechanistic details exist (Chakraborty et al , Yang et al ).…”