Soraya Karami; Sakine Faraji; Tayebeh Basaki; Sedighe Ghanaei
Abstract
The present research considered identifying drought-tolerant genotypes through an index-based analysis of stress tolerance and physiological traits in pomegranates. Ten local pomegranate genotypes in Iran were evaluated for drought stress tolerance in two different irrigation regimes, i.e., normal conditions ...
Read More
The present research considered identifying drought-tolerant genotypes through an index-based analysis of stress tolerance and physiological traits in pomegranates. Ten local pomegranate genotypes in Iran were evaluated for drought stress tolerance in two different irrigation regimes, i.e., normal conditions and severe drought stress (SDS). The experiment was arranged in a randomized block design with three replications and took two consecutive years to accomplish (2019- 2020). Indices for stress tolerance were estimated from the fruit yield of a single tree under each irrigation regime. There were significantly positive correlations among several parameters, including Yp (fruityield under normal conditions), Ys (fruit yield under SDS), mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI), and proline (Pro) content. Therefore, these indices can be applied when identifying drought-tolerant genotypes under SDS and normal conditions. The Pro content was introduced as the best physiological index to assist in indirectly selecting drought-tolerant genotypes. A negative correlation occurred between Ys and stress susceptibility index (SSI). This index may assist in identifying susceptible genotypes. Based on principal component analysis (PCA), two genotypes (MTS and PSS) performed best in fruit yield and showed a high Pro content under the SDS condition.
Ali Salehi Sardoei; Mehdi Sharifani; Mostafa Khoshhal Sarmast; Mahmoud Ghasemnejad
Abstract
Citrus species are comprised of susceptible plants that can barely tolerate freezing temperatures. To determine the relationship between cold stress tolerance (LT50) and some important physiological traits, four commercial citrus cultivars of citrus species were studied. These were Citrus unshiu, Citrus ...
Read More
Citrus species are comprised of susceptible plants that can barely tolerate freezing temperatures. To determine the relationship between cold stress tolerance (LT50) and some important physiological traits, four commercial citrus cultivars of citrus species were studied. These were Citrus unshiu, Citrus sinensis var. ‘Thomson navel’, Citrus paradisi var. ‘Star Ru by’ and Citrus limon var. ‘Lisbon’. Assessments of cold-stress tolerance were carried out at 4, -4 and -8 °C. Ultimately, the results showed that the Japanese mandarin and ‘Thomson navel’ had the highest stress tolerance (LT50). Citrus unshiu tolerated cold stress up to -8.4 LT50. The correlation coefficient demonstrated that significant, positive correlations were observed between several pairs of attributes, i.e. LT50 and total flavonoids, chlorophyll a and chlorophyll b, carotenoids and chlorophyll a, chlorophyll b and total chlorophyll, relative moisture content and malondialdehyde, as well as glycine betaine and catalase. According to the regression coefficient, a change of one unit in lipid peroxidation caused a decrease of 1.9238 units and 5.9615 units in LT50 at +4 and -4 °C, respectively. While commercial citrus cultivars were selected for cold-tolerance and other traits, the efficiency of cold-tolerance correlated more with carotenoid content, chlorophyll content and lipid peroxidation, considering the assessments at particular temperatures.
Hossein Astaraki; Hossein Ramshini; Mahmoud Lotfi; Ali Izadi Darbandi
Abstract
Development of cultivars with high yield under normal conditions and maintaining their yield under abiotic stresses is the main purpose of plant breeding programs in arid and semi-arid areas. The present study aimed to evaluate the yield stability of a collection of commercial melon varieties under drought ...
Read More
Development of cultivars with high yield under normal conditions and maintaining their yield under abiotic stresses is the main purpose of plant breeding programs in arid and semi-arid areas. The present study aimed to evaluate the yield stability of a collection of commercial melon varieties under drought stress. The trial was conducted in a field under normal conditions (plants were irrigated after 50 mm evaporation of a class A evaporation pan) and drought stress conditions (irrigation was carried out after 100 mm evaporation of a class A evaporation pan). In average, 3.32 kg fruit/plant and 2.76 kg fruit/plant were obtained under normal and drought stress conditions, respectively. The highest reduction in yield as the consequence of drought exposure was recorded for 'Mazandarani' (52%) and 'Samsoori' (48%). The most drought-tolerant genotypes were 'Mamaghani', 'Nahavandi', 'Shadegan', 'Crenshaw' and 'Suski-e-Sabz' as they had constant yield under both growing conditions. On the other hand, 'Samsoori' and 'Saveh' were the most sensitive genotypes to drought. For most of the measured traits, the values of broad-sense heritability were over 0.50 i.e. there was a large genetic diversity among melon genotypes. This variation can be utilized for selecting high potential fruit yield and drought-tolerant genotypes. Total soluble solids (TSS) (ºBrix) was 15.2% for 'Honey-Dew'. TSS (ºBrix) was obtained 10.7, 10.09, and 9.2% for Iranian genotypes of 'Khatooni', 'Samsoori', and 'Saveh', respectively. In conclusion, although some Iranian melon genotypes were recognized as drought tolerant, they need to be improved for TSS (ºBrix).