فصلنامه زیست شناسی گیاهی ایران
سال دوم شماره 3 (پیاپی 5، پاییز 1389)

Manganese (Mn) is one of the essential micronutrients for all plants but its toxicity induced unfavourable symptoms in plants. In acid soils, manganese toxicity is often more common than its deficiency. In this study, because of the importance of Lepidium Sativum in many cases such as medicinal, nutriental and economic aspects, the effect of different concentrations of Mn (0, 250, 500 and 800 µM) on some of the growth factors and biochemical characteristics were studied. The results showed that the concentrations of 500 and 800 µM of Mn reduced length of shoot, root, absorption of Zn and catalytic activity but increased Malondialdehyde content in comparison with the control. In addition, the plants that treated with 250, 500 and 800 µM of Mn had no significant effect on carotenoid content while at the same time, increased antocyanin content.

Experiments were conducted to determine the effects and post-effects of gibberellic acid (GA3) and chlormequat chloride (CCC) applying in vitro plantlet production (effects) and subsequent in vitro tuber production (after-effects) or on immediate in vitro tuber production (effects). Three concentrations of GA3 (0.1, 0.5 or 1 mg/l) and three doses of CCC (100, 500 or 1000 mg/l) with control were tested with the three cultivars (CV) namely Gloria, Marfona and Agria. To test direct effects on in vitro plantlet production plantlets were grown from explants on a standard medium containing Murashige and Skoog salts with normal vitamins. To test direct or post-effects on in vitro microtuber production the standard medium was used including 8% sucrose. The explants was treated with higher doses of CCC produced fewer stem branches on in vitro plantlets. The shortest plants with lowest numbers of leaves were observed in plantlets grown on media with 1000 mg/l CCC. Leaf area was the lowest with the highest doses of either CCC or gibberellic acid. Gibberellic acid increased the number of roots. Plantlets grown on the media with 1000 mg/l CCC produced shorter root systems. The direct effects of growth regulators on the number and size of microtubers were highly significant; both parameters were reduced by gibberellic acid. No direct effect of growth regulators could be observed for the weight of the microtubers. Post-effects of growth regulators on the number, size and weight of microtubers were also significant; cuttings from plantlets were pre-treated with CCC produced lowest numbers of microtubers with smallest size and lowest weight. Number, size and weight of microtubers were similar for the three cultivars.

The effect of cholorate different concentrations between 0 to 100 µM on high affinity transport system activity using Arabidopsis thaliana mutants atnrt2.1, atnrt2.4 and chl1-5 and transformants in NRT2.1 gene in two research sections was studied. In the first section, two pH 6 and 6.5 were used in a medium of free nitrate. 3 different nitrate and cholorate concentrations including 0, 25 and 50 µM with pH 6.5 were selected during second section. All seeds were cultured on solid medium and maintained in a controlled-environment condition. After 7 days, in order to gain further insight into the role of nitrate high affinity transport system, percentage of full expanded leaflets as indicator of high affinity transport system activity was investigated. The results showed the superiority of atnrt2.1 mutant in comparison with the other genotypes, especially on higher concentrations of cholorate, either with nitrate or without nitrate. Deregulation of AtNRT2.4 and AtCHL1 genes was not conducive to significant resistance. On the other hand, upregulation of NpNRT2.1 gene in atnrt2.1 mutant decreased percentage of full expanded leaflets. Based on these results, it was confirmed that AtNRT2.1 gene had key and important role in nitrate uptake by high affinity transport system.

In order to study the effect of foliar and soil applications of Fe-EDDHA on some qualify characteristics of peanut plants (variety NC2), two experiments were laid out separately in a Randomized Complete Block Design (RCBD) with three replications under field condition in Kiashahr harbor, Guilan province. In each experiment four levels of Fe-EDDHA were applied by one method (Foliar and Soil applications). In foliar application method, 0, 1, 2, 3 and 4 gr/lit Fe-EDDHA were sprayed on leaves at the beginning of branching as well as at the flowering period while for soil application method, 0, 5, 10, 15 and 20 kg/ha of Fe-EDDHA were applied at the time of sowing. The results showed that kernel oil in both methods of iron application decreased notably whereas kernel protein and also essential minerals such as active iron, total iron, N, P, K, Ca and Mg enhanced significantly. In both methods of iron application, higher doses of iron applications (4 gr/lit and 20 kg/ha of Fe-EDDHA) had significant positive effects on amount of essential elements. Altogether, iron soil-applied minerals had more effects compared to to iron foliar-application.

Controlling drought stress and its related problems had confronted mankind in thousands years. In other to investigate the effects of water deficit on chlorophyll fluorescence indices and the amount of proline in six barley genotypes, an experiment split plot based on randomized complete block design with three replications was conducted in Farm Seed and Plant Improvement Institute Karaj in 2002. In this study, the main plots were irrigated in five levels (0, 20, 50, 75 and 100 % of plant water requirement), and sub-plots were barely genotypes in six levels (Torkaman, Karon×kavir, Rihany, C-74-9, Ghorghan-4, Kavir×Badia). The results showed that water deficit caused chlorophyll fluorescence indices or photochemical efficiency of photosystem II declined significantly due to increasing of initial fluorescence (Fo) and decreasing of maximum fluorescence (Fm). With increasing stress, proline accumulated under water deficit increased although there were significant differences among genotypes under water deficit. Water deficit caused relative chlorophyll content decreased. However, between 100 and 75% plant irrigation no significant differences were seen. Water deficit caused grain yield decreased but canopy temperature increased significantly and genotypes with cooler canopy under control treatment were tolerant to drought and showed higher yield than other genotypes under drought condition. Means comparison of interaction of water limitation×barley genotypes showed that the highest grain yield was obtained in the plots which Karon×kavir and Kavir×Badia genotypes were applied without of water limitation and the least of it was obtained in the plots which Ghorghan-4 genotype under drought condition or with full water limitation was applied.

In botanical and taxonomical science embryological studies are specially important. In this research, developmental stages of pollen grains and ovules were studied in Centaurea iberica. The flower and buds in different developmental stages were removed, fixed in FAA, stored in 70% ethanol, embedded in paraffin and sliced with a microtome. Staining was done with Hematoxilin and Eosin. The prepared slides from different developmental stages were studied carefully using a light microscope. On the basis of this research results, ovule was anatropous, bitegumic and tenuinucellate. The development of the embryo sac followed the mono-sporic, polygonum type. After the meiosis, megaspore tetrads had linear arrangement. First, embryo sac was very small, so that its nuclei were compressed linearly but in maturation progress, embryo sac sustained longitude growth considerably. The anther was tetra-sporangiate. InC. iberica, the tapetum was plasmodial with bi-nucleate cells. In species microspore tetrads were observed with tetrahedral, tetragonal and linear arrangement. Pollen grains were two-celled and tricolpate.

Quantitative and qualitative study of phenolic compounds (phenolic acids, flavanols and anthocyanins) in peel of Gala apple were implemented using analytical HPLC, fluorescence microscopy and epi-illumination light microscopy at three different growing stages [1- fruit early growing stage 2- mid-stage of fruit development (80 days after full bloom) 3- during commercial harvest time]. The results showed qualitative and quantitative differences between diverse growing stages regarding the content and accumulation of phenolic compounds. HPLC and microscopic studies showed that anthocyanin content of peel increased progressively during season. Microscopic data revealed that the highest anthocyanin accumulation occurred at the commercial harvest time. Our results showed that phenolic acids content decreased till mid-season but then, after their content had increasing pattern until commercial harvest time. Microscopic pictures verified this claim as well. Simultaneous comparison of HPLC and microscopy of derived data showed that flavanol content of peel increased towards mid season. In contrast, a drastic decline was recorded for flavanols during commercial harvest time. Comparative survey of microscopic and chromatographic data indicated that the great potential of fluorescence microscopy for study of phenolic compounds in apple peels. In brief, integrated study of phenolic compounds by means microscopic and chromatographic techniques is fast and easy methods for identification and quantification of phenolic compounds leading to accurate conclusion regarding elevation of apple fruit quality criteria.