Journal of Plant Process and Function

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order to study some physiological traits and the changes of nutrient uptake in potato plantlets under in vitro conditions in response to osmotic and temperature stresses, this research was conducted as a factorial experiment in a block design. The first factor was osmotic stress induced by PEG - 6000 in four levels (0, -0.5, -1 and -1.5 MPa), and the second factor was temperature at three levels (15, 25 and 35 ° C). The third factor was potato plantlets consist three promising clones (143, 301 and 306) and two commercial cultivars (Marfona and Picasso), which were planted in MS medium. Eight weeks later, plantlet’s fresh and dry weights, number of developed leaves, the content of P, K, Ca and Na in above parts of plantlet were measured. The results showed that the simple effects of factors as well as their interactions at 1% level were significant. Mean comparison of treatments showed that the simultaneous effects of stresses reduced fresh and dry weights, leaf number as well as the uptake of P, K, Ca but Na uptake increased. According to the results, the highest fresh, dry weights were observed in non- heat stress conditions (25 ° C). On the other hand, increasing of temperature from 15 to 35 ° C, increased the absorption of P and Na, but the amount of K and Ca were greatest at 25 ° C (no temperature stress).

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12 hybrides of tomato and their parents were evaluated for their response to drought stress in a randomized complete block design with three replications and three irrigation levels (FC, 60%FC, and 40%FC). The studied genotypes were including Kingstone, Petoearly, Bitstoik, LA1607, LA2656, LA2080 and LA1579. Experiments on crossing the genotypes, seedling production and field evaluation, were done in experimental greenhouses and experimental field of Ilam University in 2014-2016. The studied traits consisted of proline, MDA, peroxidase, catalase and ascorbate peroxidase, Relative Water Content (RWC), Chlorophyll a, b and total, electrolyte leakage, total yield, potential yield and single plant yield. The statistical analysis showed that drought stress significantly affected all assessed traits under drought condition. Increase in Proline and MDA content was observed in all genotypes under drought stress. The highest values of proline )31.93 µMgFW^-1) was obtained under severe stress in Petoearly× LA2080. RWC, total yield, potential yield, single plant yield, Chlorophyll a, b, catalase and ascorbate peroxidase contents were reduced and proline, electrolyte leakage and peroxidase content were increased by increase in drought stress. Under severe drought stress, the highest amount of total yield (15.74 t.ha^-1) was observed in LA2656×Petoearly hybrid, Petoearly line (19 t.ha^-1) and LA1579 tester (32 t.ha^-1).