م. رضایی

This research was carried out to provide suitable cotton seed for seed propagation in dryland. In this study, the potential of cotton seeds that have been stressed for the third-consecutive year was investigated to evaluate water stress memory responses. The experiment was arranged in split-plot factorial design with four irrigation levels of W0 (No- irrigation), W1 (33% FC), W2 (66% FC), and W3 (100% FC), as the main factor, and five seed treatments (four third-stressed seeds, i.e. S21 to S24, and registered seed), as a sub-plot. Seeds of cotton were grown under different levels of water-stress exposure for three crop-seasons. As results showed, S32 received water stress signal in both W0 and W3 conditions through physiological mechanisms change. Seeds of S32 accumulated the lowest ABA and the highest calcium in exposure to W0 and W3. Enhancement to superoxide dismutase and Aspartate peroxidase activity in leaves of S32 in exposure to W0 and W1 is another memorial stress mechanism for scarce water acclimation. The highest-potential thirty-boll weight, thirty-fiber weight, and first-harvesting yield were obtained from S32 against W0, W1, and W2.. Also, the seeds of S32 had the most seedling vigor and germination percentage in exposure to W0, W1, and W2. It can be concluded that stress memory, via modification of physiology and morphology of plant behavior, helps plants to tolerate water deficiency when subjected to recurrent drought.

The Tomato Leaf Miner (TLM), Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a cosmopolitan tomato pest that has driven a renewed reliance on pesticides in tomato production, negatively affecting biological control of other pests and creating environmental and health hazards. We tested five locally important Iranian tomato cultivars (TD, Karon, Petoprid, Matin, and 8320) for constituitive resistance to TLM by comparing its biological performance and life table parameters under standardized laboratory conditions (27.5±1°C, 65±5% RH, 16 L:8 D hours photoperiod). Survival and developmental rates of immature stages varied significantly among cultivars, as did female fecundity and main parameters of the life table. Karon was most suceptible, affording 90% juvenile TLM survival, the fastest development, and the highest female fecundity, with cultivar 8320 not significantly different in these regards. By contrast, Matin ranked most resistant; i.e. only 59% of larvae survived, and female fecundity was almost halved. TD was the next most resistant, being not significantly different from Matin in these metrics. The intrinsic rates of increase (r), in descending order, were Karon (0.178), 8320 (0.169), TD (0.146), Petoprid (0.138), and Matin (0.111). Matin and TD had the highest densities of glandular trichomes on adaxial leaf surfaces. These findings indicate that the Matin, Petoprid and TD are more resistant than the other cultivars and have potential as one component of an IPM strategy to manage T. absoluta.