Journal of Plant Physiology and Breeding
Volume:5 Issue: 2, Summer-Autumn 2015

Salinity is one of the most challenging problems that adversely affects growth and development of plants. Therefore, understanding of the mechanisms that enable plants to adapt to salinity stress will ultimately help in the selection of stress tolerant cultivars for exploiting saline soils. The main objective of this study was to examine the effects of NaCl on some physiological and biochemical characteristics of two rice varieties, IR29 (salt sensitive) and FL485 (salt tolerant), exhibiting different sensitivities to NaCl. NaCl induced a progressive increment in Na concentration of both cultivars, however, it was more marked in the sensitive cultivar IR29. A higher level of sugar and a delay in chlorophyll degradation together with less chlorophyll degradation were observed in the salt tolerant rice. Salt stress may promote sugar accumulation, thus preventing the degradation of chlorophyll. Salinity stress induced an accumulation of starch in cv. FL485. It is possible that adjusted carbon partitioning could have an important implication on salinity tolerance. It is suggested that allocation of sugars into starch may involve in salinity tolerance by avoiding metabolic alteration.

In order to determine the best developmental stage of soybean at which maximum seed quality is attained under different shadings (S1, S2, S3: 0, 35 and 75% shade, respectively) and irrigation treatments (I1, I2, I3, I4: irrigation after 60, 90, 120 and 150 mm evaporation from class A pan, respectively), two split plot experiments using randomized complete block design with three replications were conducted in 2011 and 2012. Seeds were harvested at five day intervals in eight stages. Maximum seed weight (mass maturity) was achieved at 41-54 days after flowering. Seed filling duration decreased with decreasing water supply, but it was increased by shading. As a result, maximum seed weight, germination rate and seedling dry weight of seeds from shaded plants were higher than those of unshaded plants. However, minimum electrical conductivity and maximum germination percentage of seeds from shaded and unshaded plants under different irrigation treatments were almost similar. Maximums of seed quality parameters were obtained 1 to 9 days after mass maturity, depending on the light availability and irrigation intervals. At earlier harvests, because of immaturity, and at later harvests, due to aging, seed physiological quality was low. It was concluded that high quality seeds of soybean can be produced under different irrigation and shading treatments, providing that the seeds are harvested at about 16-20% moisture content.

An experiment was conducted to investigate the effects of K/Ca ratios of nutrient solution on physiological traits, cut flower vase life and postharvest changes of rose. The main experiment was factorial based on completely randomized design with two cvs. of rose (Magic Red and Capitol), five K/Ca ratios in the nutrient solution (4:4, 6:4, 6:3, 8:3, 10:2) and three replications. Increasing the K/Ca ratio in the solution led to accumulation of K in the leaves but decreased the Ca concentration of the leaves. Furthermore, K/Ca ratio of the leaves was affected by K/Ca ratio of the nutrient solution and highest ratio of K/Ca was recorded for the leaves of plants fed with nutrient solution of 10:2 K/Ca ratio and the lowest K/Ca ratio of leaves was observed for plants which supplied with the nutrient solutions of 4:4 and 6:4 K/Ca ratios. The highest chlorophyll index was recorded for Capitol cv. and K/Ca ratios of nutrient solution had significant different effects on chlorophyll fluorescence. It was noted that rising K/Ca ratio caused lower longevity of cut flowers in both cvs. The highest necrosis of petals was occurred at 10:2 ratio of K/Ca and Magic Red cv. was more sensitive with the highest percentage of necrosis. The appropriate K/Ca ratio was obtained in the 6:4 ratio in terms of nutritional balance, reduced antagonistic effects of K and Ca, postharvest quality and more longevity of cut flowers.

In order to evaluate the tuber fresh weight and some physiological attributes of Agria potato cultivar in response to water deficit stress and mycorrhiza inoculation, a field trial was conducted as a split plot scheme based on randomized complete block design with three replications at the research site of Islamic Azad University, Tabriz Branch in 2012. Four water levels including: irrigation after 60 (S0) mm evaporation from class A pan as the control and irrigation after 90 (S1), 120 (S2) and 150 (S3) mm evaporation from the pan as water deficit stress conditions were arranged in the main plots and four levels of arbuscular mycorrhizal fungi (AMF) including: no AMF (M0), inoculation of Glomus etunicatum (Ge) (Becker and Gerdemann), Glomus intraradices (Gi) (Schenck and Smith) and dual inoculation of the two species (Gei) were arranged in the sub-plots. Water application and AMF inoculation had significant effect on all of studied attributes. Increasing of water deficit stress intensity increased stomatal resistance and decreased leaf relative water content and tuber fresh weight. On other hand, positive effect of AMF inoculation was observed on stomatal resistance, leaf relative water content, leaf chlorophyll content and tuber fresh weight. Also, significant interaction between water application and AMF inoculation was observed for stomatal resistance, leaf relative water content, leaf chlorophyll content and tuber fresh weight. In general, water deficit stress decreased tuber fresh weight in non-mycorrhizal and mycorrhizal potatoes. In all of water levels, maximum tuber fresh weight was observed by inoculation with G. intraradices.

Effects of different concentrations of IAA (0, 0.3, 0.6 mg/l) and 2ip (0, 0.3, 0.6, 0.9, 1.2 mg/l) and their combinations on callus induction and shoot regeneration of hypocotyl and its thin cell layer (TCL) explants in tomato was studied. Explants were prepared from hypocotyls of seedlings in the aseptic condition. Hypocotyl segments were more efficient than TCL explants for callus induction and it was occurred on the 96.0 percent of hypocotyl explants as compared to 76.5 percent of TCL explants. The mean diameter of formed calli on the hypocotyl explants were significantly more than TCL explants. The calli on hypocotyl explants were more regenerative than calli produced on TCL explants and 60.1 percent of calli produced on hypocotyl explants developed the shoots while the regenerated shoots from the calli of TCL explants were 21.45 percent. Percentage of shoot induction on TCL explants was maximum (47.44 percent) in the medium containing 0.3 mg/l 2ip and 0.6 mg/l of IAA. Explant typehad significant influence on the shoot number per callus. Calli developed on TCL explants regenerated more shoots significantly than hypocotyl explants. The recorded shoot number per callus of TCL and hypocotyl explants were 6.45 and 3.22, respectively. The mean length of developed shoots on the hypocotyl segments was significantly higher than that of TCL explants and maximum length of shoot was obtained on the medium containing only 0.3 mg/l IAA.

Cumin (Cuminum cyminum L.) is one of the most important herbs and medicinal plants that allocate main part of medicinal plant export in Iran. This investigation was conducted to study the effects of drought stress on important agronomic traits of different cumin ecotypes from the major cumin cultivation of the country. Forty-nine ecotypes from different regions of Iran were planted in a simple lattice design layout with two replications in drought stress and non-stress conditions during two years (2012 and 2013). Characteristics including number of umbels per plant, number of seeds per umbel, seed weight, harvest index and seed yield were evaluated. The combined analysis of variance showed significant differences among genotypes, among environments and the genotypes × environment interactions. The low irrigation (soil water supply at 30% field capacity) after flowering stage decreased the value of all traits but at different extent. The highest adverse effect was related to the seed yield. In average of both years, water shortage decreased seed yield about 33.6 percent. Moreover, 1000 seed weight was affected by the environmental condition at the lowest extent (3.8 percent). Also, based on means comparison, the highest and the lowest seed yield on the average of two years belonged to ecotypes from North Khorasan-Baneh in the normal condition (105.07 g.m-2) and North Khorasan-Esfaraien under low irrigated condition (20.53 g.m-2), respectively. Considering all evaluated traits under both conditions, ecotypes from North-Khorasan (Baneh) and Semnan (Shahmirzad) are proposed as good candidate ecotypes to further research in future.