نشریه علوم و تحقیقات بذر ایران
سال ششم شماره 4 (زمستان 1398)

Maize ear Sheller has important role in maize seed processing system. In this research, technical operation of a fabricated maize ear Sheller by Iranian company was investigated. Operational capacity, shelling efficiency, cleaning efficiency and seed damage percentage were studied. In addition, germination and rootlet percentages of shelled maize seeds were analyzed using T-student test. Results showed that, fabricated Sheller has suitable operation. Operational capacity calculated 2.7 (ton/h) in normal condition. When moisture content of maize seed was less than 13% (w.b) and Sheller had suitable feeding, more than 99% of cobs were shelled and physical damages of seed decreased to less than 0.4%. Cleaning efficiency for output maize seeds was 95% and seed remained on cob was less than 1%. Shelling operation did not have negative significant effects on germination and rootlet percentages of maize seeds and reduced less than 0.5 and 2% respectively. This machine can be recommended for medium scale corn seed fields.

This study was laid out in order to evaluate the effects of artificial ageing and natural storage on seeds germination traits, cation leakage and viability of chickpea seeds under both artificial ageing and natural storage and comparison of them in Gorgan University of Agricultural Science and Natural Resources at 2014. The experiment was conducted in completely randomized design with four replications. Treatments were 8 ageing levels such as (2 years, 4 years natural storage, 1, 2, 3, 4, 5 days of artificial ageing and control). In the present stude some traits such as germination percentage, normal seedling percentage, germination rate, seed vigor index, electrical conductivity, lipid peroxidation and seed Na and K before and after leaching and their amounts in soluble after leaching were studied. The results of analysis of variance showed that the effect of aging treatment was significant on all traits except seed Na before leaching. The results of the mean comparison showed that the reduction of germination percentage, germination rate, seed vigor index and normal seedling percentage in 4 and 5 artificial ageing days were higher than 2 and 4 natural storage years. MDA production, electrical conductivity, Na and K lekeage in increased by increasing of artificial ageing to 5 days that was more than 2 and 4 natural storage years due to non-ability of membrane to keeping their permeability. The increasing of aging levels result to increases of amount of K and Na in seeds tissues. Seed dying by tetrazolium ans nitro blue tetrazolium showed that increasing of seed aging result to reduction of seed viability that in severe artificial aging was higher than natural storage treatments. During seed aging Lipid peroxidation damaged to cell membrane and electrolyte lekeage was increased. Then, seed viability was decreased and results to decreasing of seed germination percentage and rate and normal seedling production. These results reviled that effect of artificial ageing and natural storage on germination, cation leakage and viability of chickpea seeds was same and can uses for chickpea storing programs, whereas their mechanisms may different.

This experiment was conducted to evaluate the allelopathic effects of bulb and leaf aqueous extracts of narcissus (Narcissus tazetta L.) on germination, growth and physiological characteristics of two weed species namely couch grass (Agropyron repens) and wild oat (Avena fatua). For this purpose, two seprate experiments were conducted in a completely randomized design with three replications in laboratory and greenhouse conditions in 2017. Treatments included three levels of leaf and bulb extracts (1, 2 and 3 % w/v) along with control (distilled water). The results showed that increasing the concentrations of leaf and bulb extracts reduced germination percentage and germination rate of the seeds, root length, plant height and chlorophyll content a, b and total of couch grass and wild oat, but total soluble sugars and antioxidant activity increased. The concentration of 3 % of the bulb extract reduced seed germination percentage, root length, plant height and total chlorophyll in couch grass by 81, 42, 38 and 49 %, and in wild oat by 63, 44, 36 and 40 % compared to the control plant, respectively. The results of this study showed that can be used the allelopathic effects of leaf and bulb extracts of narcissus in order to biological control of these two weeds.

In order to investigate the effects of seed aging and application of polyamines on the germination indices, gene expression and antioxidant enzymes activity in barley, a factorial experiment conducted based on completely randomized design with three replications. Treatments consisted of three aging levels (0, 11 and 14 days) and polyamines (putrescine and spermine). Germination indices, activity of antioxidant enzymes and expression of some genes were studied. Results showed that aging decreased germination percentage (GP) about 24 % in comparison to the control, but putrescine application increased GP about 18%. Germination rate (GR) decreased in the seeds aged for 14 days about 36 % and spermine increased GR about 87.5 %. Plumule and radicle dry weight increased 2 and 3 folds, respectively in putrescine and non-aged treatment rather than control. The highest activity of ascorbate peroxidase, peroxidase, polyphenol oxidase and superoxide dismutase (SOD) observed in the seeds aged over 14 days with putrescine application. Relative expression of genes encoding SOD and glutathione transferase was 8 and 22 folds greater, respectively in putrescine applied seeds aged for 14 days over control. Relative expression rate for HSP90 and PR10 genes was 5 and 8 folds greater than control, respectively in the same treatment. In conclusion, putrescine application invigorated the weak barley seeds and it can be related to improving the oxidative state of cells, greater protein conservation by high activity of HSP90 and increasing in the endogenous levels of seed hormones. Further in depth studies require to prove the role of hormones in seed vigor.

In order to evaluate Germinability and seedling vigour associated with peanut seeds of the plants had been sprayed with methanol and mthylobacterium a laboratory research at 2 years was conducted in Islamic Azad University of Rasht. This study was conducted using standard germination test, cold and accelerated aging test. Each test using factorial experiment based on randomized complete block design with 16 treatments (bacteria populations mthylobacterium in unit of CFU in 4 levels, 106, 108 and 1012 and 4 levels of methanol 0, 10, 20 and 30 % v/v) in three replications. characteristics studied were: final germination percentage, seedling  vigour, root dry weight, hypocotyl dry weight , shoot dry weight and seedling dry weight. The results showed that the effect of year was significant on all studied characteristics in all the tests. Bacteria population only significant effect on the final germination percentage in all the tests. The amount of methanol had significant effect on all studied characters in the three tests. Interaction between the bacterial population with amount of methanol only the final germination percentage in standard germination and cold tests had a significant effect. Comparison of means showed the highest final germination percentage in the population of bacteria 1012 CFU was observed in all the tests. Most of all investigated characteristics in all tests was 20 percent methanol.

Several tests have been introduced to determine the seed vigor, that one or some of them are suitable for each plant species. This study was conducted to compare electrical conductivity, imbibition and hiltner tests to determine the seed vigor in lentil. The research was done in two sections of laboratory and field at Razi University during 2015-16. In the field, eight lentil seed lots, which were different in terms of cultivar and age, were planted. In the laboratory, this eight lentil seed lots were compared by electrical conductivity, imbibition and hiltner tests. The results of the field experiment showed that the lentil seed lots were significantly different in percentage and rate of seedling emergence, mean daily emergence and mean time to emergence. The laboratory experiment showed that there were significant differences among seed lots in conductivity and hiltner tests, but were not in imbibition test. Orthogonal analysis in the conductivity and hiltner tests demonstrated that the new seed lots had higher vigor. Based on the correlation analysis, the conductivity and imbibition tests had no correlation with the seedling emergence characteristics in the field, but the normal seedling percentage in hiltner test had significant positive correlation with the percentage (r=0.630) and rate (r=0.498) of seedling emergence in the field. So, it seems that to predict seedling emergence in the field, conductivity and imbibition tests have inappropriate ability, but hiltner test has appropriate ability.

A major constraint limiting saffron (Crocus sativus L.) cultivation is the difficulty of obtaining high quality corms for propagation. This study was conducted to compare foliar application effect of three fertilizer types at different times on corm growth and production in saffron as a split plot expreriment in randomized complete block design with three replications during 2013-2014 growing season in Ein abad, in a village in Torbat-e Heydarie of Khorasan Razavi Province. Main plots consisted of Delfan Plus, Ultrasol 1, 2 fertilizers and control, sub plots were three application different times include 1&25 March and 14 April 2014, respectively. Measured traits was including dry weight, replacement corms size and the total number of mother and replacement corms. Analysis of variance showed significant effects of different treatments of foliar application and foliar spray time on size, weight of replacement corms in saffron, but the effect of treatments on the total number of mother and replacement corms per unit area and their interaction effects were not significant. In conclusion, results of this study demonstrated all fertilizers compared to control treatment and Delfan Plus fertilizer compared to other fertilizers and also control treatment (respectively 13.5, 13.6 and 13%) had more increasingly effect on size, weight of replacement corms. Among foliar spray time treatments, on 25 March, 2014 had superiority in positive impact on size, weight of replacement corms compared to other times. So that foliar spray time on 25 March, 2014 compared to 1March and 14 April 2014 caused to increase 6.6% and 11% respectively of daughter corm size, therefore among applied fertilizers, Delfan plus was best fertilizer and also among application times, on 25 March, 2014 was the most appropriate time.

Increased salinity tolerance in barley basic requirement is to sustain production in saline areas. The present study was concluded to examine the effect of salinity stress on barley varieties in order to find the most tolerant of varieties in early growth stages based on morphological and physiological traits.The research aimed at research laboratory of Islamic Azad university, Ahvaz branch in 2015 in factorial experiment in basis completely randomized design with 3 replications of 20 varieties as the first factor and salinity stress with NaCl at 4 levels of zero (distilled water), 5, 10 and 15 ds/m as the second factor was implemented. Analysis of variance showed that there was a significant difference between varieties for most of traits that indicates there is sufficient variation between varieties. The principal components analysis, 11 studied traits is divided into 2 components on the basis of 62 % of the data changes can be justified. Cluster analysis divided varieties in three clusters. The summary results of the principal component analysis, biplot and cluster analysis revealed that varieties of Gorgan, Kavir, Behrokh, Torkaman and Zarjo had better tolerance to salinity stress than other varieties and stated followed by Fajr 30, sahra, Reihan 48 and Karon.

This research conducted in order to study on effect of seed moisture content and storage duration on some germination and vigor traits of 3 wheat cultivars at Mazandaran province as split split plot based on complete randomized design by 4 replications. Treatment were Morvarid, Milan and N8019 cultivars seeds which by 10, 12, 14 and 16 percent seed moisture content harvested and for 2, 3 and 4 month after harvest stored. By standard germination test, final germination and normal seedlings percent, mean germination time, seedling length and dry weight and seedling length and weight vigor indices (respectively seedling dry weight and length multiplication in final germination percent) determined and electro conductivity measured. Results revealed that, harvested seeds at 10 percent moisture content stored for 2 month, Milan and N8019 cultivars seeds stored for 4 month and Milan cultivar seeds harvested at 12 percent moisture content had the most final germination percent, 98 percent. Morvarid and Milan cultivars seeds harvested at 10 percent moisture content and stored 2 month and N8019 cultivar seeds harvested at 12 percent moisture content and stored 2 month had the most normal seedlings percent, 98 percent. The lowest mean germination time, 1.210 day, belonged to Milan cultivar seeds harvested at 10 percent moisture content and 2 month stored. Based on this research results, optimum seed moisture content at harvest for Morvarid cultivar was 10 percent and for Milan and N8019 were 12 percent and suitable seed storage duration was 3 months for Morvarid cultivar and for Milan and N8019 were 2 months.

True-to-type and pathogen-free plant propagating materials are among the most necessary inputs to achieve sustainable agriculture. Some of plant pathogens and pests are transmitted via true seeds to the next generations in certain circumstances but all are transmitted through vegetative plant propagating materials. Using informal propagating materials and successive cycles of vegetative propagation has caused accumulation of pathogens and pests specifically in plants propagated by means of tubers, corms and rhizomes. This, in turn, has resulted in crop yield reduction in quantitative, qualitative and salability points of view. This phenomenon called seed degeneration and is very common in regions where farmers, for any reason (s), use informal seeds produced on-farm or acquired from markets. Several factors including climate, life cycles of pathogens and pests and their relation with other entities and environment influence seed degeneration. The present article focuses on details of seed degeneration, related factors and finally on integrated strategy based on these factors to prevent/mitigate this phenomenon.