Fruit of two almond, Prunus amygdalus Linnaeus, cultivars (Retsou and Truoito) containing diapausing larvae of Eurytoma amygdali Enderlein, were collected in early August from coastal areas in northern Greece. Some larvae were removed from the fruit and maintained singly in open plastic vials and others left in the fruit until the end of the low-temperature period. They were kept at a low temperature of 10°C from the beginning, or after 8 weeks at 20°C. The larvae were subsequently maintained at 20°C and whether they completed the two diapause stages was recorded for 60 more weeks. When the larvae in vials, were kept initially for 8 weeks at 20°C, most of those from Retsou and all of those Truoito almonds completed the first stage of diapause. Of the larvae in the fruits, most of those in Truoito but less than 50% of those in Retsou almonds completed the first stage of diapause after 8 weeks at 20°C. Larvae from different orchards and different almond cultivars differed in diapause intensity. When the larvae were kept at a low temperature of 10°C from the beginning for 4, 8 or 16 weeks and then at 20°C they completed the second diapause stage synchronously, but the time of completion was delayed, and depended on the duration of the low temperature treatment. In several cases the time to diapause completion was bimodally distributed and the relative size of peak depended on the duration of the early exposure to low temperature.
We studied water relations and gas exchange in six almond genotypes grafted on GF677 in response to withholding irrigation for 14 days and a subsequent 10-day rehydration period. The responses to drought stress significantly differed in the almond genotypes; the tolerant plants were distinguished and monitored. Leaf relative water content (RWC) decreased by more than 23%, leaf water potential dropped to less than -4.3 MPa, and electrolyte leakage increased to 43% in dehydration-sensitive genotypes. Photosynthesis (PN) and stomatal conductance (gs) of drought-sensitive genotypes were significantly reduced by 70% and 97% in response to water deficiency. Water stress significantly enhanced wateruse efficiency up to 10 folds in drought-tolerant almonds. The difference between leaf temperature and its surrounding air temperature (ΔT) increased significantly to more than 187% under water stress in drought-tolerant genotypes. In addition, the reduction in the g s and further ability to preserve RWC were involved probably in drought-tolerance mechanism in almond. Negative significant correlations were found between ΔT, PN, and gs. Based on the correlations, we suggested that ΔT could be used as a simple measurement for monitoring water stress development in the irrigation management of almond orchards. In conclusion, ‘Supernova’ and the Iranian genotypes ‘6-8’ and ‘B-124’, were found to be more droughttolerant compared with other genotypes in this experiment., S. Karimi, A. Yadollahi, K. Arzani, A. Imani, M. Aghaalikhani., and Obsahuje bibliografii