فصلنامه پژوهش های تولید گیاهی
سال بیست و یکم شماره 2 (تابستان 1393)

Postharvest fruit quality is so affected by harvest time in Hayward kiwifruit. The objective of this study was to determine the effects of harvest maturity and storage time on ‘Hayward’ kiwifruit quality. The fruits were harvested based on total soluble solids (TSS) content (5.5, 6.5, 7.5 and 8.5% average) and then stored in 0.5 oC and 80-90% RH, for 18 weeks. The samples had taken in 6, 12 and 18th weeks during storage and the changes of water loss, firmness, TSS, TA, TSS/TA, ascorbic acid, pulp color index (L*, a*) and sensory analysis were assessed. Results showed fruits which harvested an early time had the lowest water loss during storage. Fruits which harvested at 6.5 oBrix maitained better firmness during 12 till 18 weeks of storage. Generally, TSS increased in all treatments during storage. The TA percentage was the lower in the end of storage especially in the fruits which harvested with higher TSS. The fruit pulp lightness (L*) of all fruits gradually decreased, particularly in week of 12 (48.46 to 58.1) but was lower in the fruit harvested with higher oBrix. The value of a* increased insignificantly in all fruits during storage. Based on physicochemical and sensory analyses is founded that the Hayward kiwifruit harvest time is when the fruits had at least 6.5 oBrix. However, if fruits picked up with 7.5 oBrix, it will be suitable for preservation of fruit quality and flavor to end of storage.

Self-incompatibility is one of the most important difficulties in almond production which reduce fruit set drastically and makes orchard management difficult. Therefore, breeding of almond to produce self-compatible genotypes is very important. In this research, level of self compatibility in 50 selected genotypes of different crosses was studied using linked markers through PCR analysis and fruit set. Result showed that 31 genotypes had band with length of 450 bp which were identified as self-compatible genotypes. Study of fruit set after self pollination showed that 31 genotypes with fruit set more 5% identified as self-compatible. The most fruit set after self pollination observed in genotypes number 42, 45 and 24 to rate 26.94, 25.1 and 25 percentages, respectively. Comparing fruit set percentages after self pollination with open pollination showed that selfing reduced fruit set percentages but the decrease of the fruit set in some genotypes was very low. The result of investigation of fruit qualitative and quantitative characteristics showed, in total, very self compatible genotype number 24, was better than other genotypes. This genotype produced fruit, nut and kernel with medium size. Fruit, nut and kernel weight was 10.80, 3.98 and 1.41 g, respectively. Nut and kernel color of this genotype was bright and its kernel taste was sweet. The beginning of flowering in this genotype was later than other genotypes and fruit harvest dater was sooner than other genotypes. In total in this research, genotype number 24 identified as suitable genotype.

Induced mutation is one of efficient methods for improvement of qualitative and quantitative traits in crop plants. A research was conducted to study on variability of morphological traits in rice after application of ethyl methane sulfonate (EMS). Neda cultivar was treated by 0.1% EMS mutagen and then variability of qualitative and quantitative morphological traits were evaluated in 212 M2 mutants. On the basis of visual observations, stem color and its angle were altered in two and five mutant lines, respectively and two aromatic lines was identified based on aroma test. Also, mean of plant height and heading date, showed significant decrease and relatively significant increase, respectively. Twenty two mutant lines were selected based on further tillering and vigor and along with original cultivar were evaluated in some quantitative traits. ANOVA showed that there were very significant differences between the studied genotypes in all evaluated traits. The effect of this selection was desirable on most studied traits, so that highest effect was observed on filled kernels/panicle (41.3%), total kernel number (37.4%), tiller number (29.4%, plant yield (25%), plant height (-5%) and lowest effect was observed on 100-kernel weight (-0.05%) and heading date (2.4%). Seven lines produced significantly higher yield than original cultivar, that in most of them total kernel number and filled kernels showed a significant increase relative to original cultivar. Based on mean comparison three mutant lines viz. MT-A, MT199 and MT44 were identified as high-yielding lines. On the basis of the results of this research it can be concluded that mutation technique is a suitable tool for inducing genetic variability in different rice traits and that visual selection in M2 generation is efficient for identification of high-yielding mutant lines.

Climate change affects on precipitation and temperature patterns and hence, may alter the crop yeild. This research was conducted to evaluate the effects of climate change on soybean yield in Gorgan using soybean growth simulation model (SSM) under different climatic scenarios. LARS-WG model was used to generate temperature and rainfall data for future period (2013-2042) under emission scenarios of B1, A2 and A1B. The generated and observed weather data for baseline period of (1985-2012) were considered as inputs for a crop-weather model namely, SSM. Various periods of phenology, biological and grain yield for both irrigated and rainfed planting were simulated by defining eight different dates of sowing ranging from the May 11th to 24th July with 10 days interval. Test of significance of means showed an increasing trend in daily maximum and minimum temperature for most of the months and for mean monthly values of rainfall in fewer months. The simulation result of soybean yeild by SSM model indicated that there is no significant difference between initial stages of soybean phenology under impact of emissions scenarios data and observation data but stage length to physiologic and harvest maturity during future periods shorted to 5 days and for late cultivation reached to more than 10 days. Biological and grain yield decreased slightly for irrigated cultivation, and increased for rainfed cultivation in earlier planted crops. Finally, rainfed cropping of soybean is not common in the region, it can be concluded that climate change will not significantly affect on water requirement and yield of soybean in Gorgan region.

Soybean is one of the most important oil crops in Iran. The objective of this study was to develop a soybean growth and yield simulation model for the use in analyzing the effects of climate, soil, crop management and cultivar characteristic (habit cultivar) on soybean yield under north Khorasan conditions. Crop growth aspects were arranged in sub-models including phonological development, leaf area variations, dry matter production and partitioning. A soil water balance sub-model was included to simulated soil water dynamics and severity of water stress. The model uses a daily time step and readily available weather, soil and crop management. The model was tested for north Khorasan conditions. The observed grain yield varied from 2600 to 4800 kg-1ha with mean 3600 kg-1ha. Also, range for simulated grain yield was between 3060 to 4100 kg-1ha with mean 3640 kg-1ha. The regression coefficients of observed grain yield against simulated grain yield (a=1799±759, b=0.51±0.25) on based confidence limits 95% hadn’t significant difference with 1:1 line coefficients (a=0, b=1). The coefficient of determination (R2) and index of agreement (d) was 0.67 and 0.85, respectively. Root mean square error (RMSE) and coefficient of variations were estimated 458.3 kg-1ha and 12.6%, respectively. It was concluded that this model could be used for estimation of grain yield against with proper precision under north Khorasan conditions.

In order to describe the spatial and temporal distribution of saffron weed seedling populations, geostatistical techniques were used under different management conditions and theirs effect on saffron above ground biomass production over the two growing seasons at three saffron fields each with an areaof 2000 m2, located in Southern Khorasan, Iran. The dominant weed population and saffron leaf dry weight were recorded at 144 points of each saffron field based on a 4×4 m grid at the end of plant growing season. Saffron leaf dry weight was determined at the same place of weed seedling in two years. Weed spatial autocorrelation was indicated by semivariogram analysis and weed density and saffron above ground biomass relationship were determined by cross semivariogram analysis and Spearman’s correlation coefficient at the end of two growing seasons. The density and spatial distribution of weed seedling varied under different weed management practices at both years. Semivariograms analysis showed moderate to strong spatial dependence (50.1-89.6%) for total weed distribution patterns based on fields and years. Saffron above ground biomass dry weight showed moderate to strong spatial patterns (51.1-92.5%) on the three fields. Cross-semivariograms analysis and Spearman’s correlation coefficient showed considerable spatial continuity between saffron above ground biomass and weed density patterns on the different fields. Baesd on our results, in spite of different weed control methods, patchy distribution of weeds can cause spatial heterogeneity in above ground saffron biomass on the fields.

The decrease of the agricultural crops growth is one of the important effects of salinity that in these conditions sodium and chloride ions in shoots and roots have been increased however potassium and calcium ions have been decreased. One of the mechanisms to work with salinity presence of calcium ion that improved the adverse effects of salinity. Maintaining the proper amount of calcium ion in the soil, the toxic effect of sodium ions is controlled. In this study, the effects of three different nutrient solutions, including the sodium chloride concentration with 0, 30, 60 and 90 mM, calcium chloride concentrations with 0, 10, 20, 30 mM and sodium chloride + calcium chloride respectively to the same concentration were reviewed and investigated on two cultivated tomato varieties in a hydroponic form and pots containing Coco peat. In the vegetative growth stage, relative water content of tissue and cytoplasmic membrane stability and leaf chlorophyll concentration after removal of the root and shoot dry weight were measured. Results showed that increase of salinity caused a significant reduction in relative water content of tissues, cytoplasmic membrane stability and chlorophyll concentration in leaves. Dry weight yield of roots and shoots also decreased with increasing the salinity so that all the characters were lowest in 90 mM of sodium chloride concentration. The results showed that the growth terms of calcium chloride and chloride + calcium chloride solutions were better, as the 10 mM concentration of calcium chloride has a significant impact on improving the damage caused by the salinity.

Salinity is a most important environmental stresses in a pomegranate-growing area of Iran. In other hand, photosynthesis and nitrogen metabolism are the most important physiological and biochemical processes in plants. In this experiment, influences of effective microorganisms (EM) (0 and %1) on the photosynthetic responses of potted pomegranate (shishe-kap cv.) under four levels of salinity stress (0 mM, 50 mM, 100 mM and 150 mM salinity includes: NaCl (10 part) and CaCl2 (1 part)) with 4 replications were investigated. Results showed that the application of EM reduced the negative effects of salinity on photosynthetic responses. Also chlorophyll b and total chlorophyll content, stomatal conductance, photosynthetic rate and nitrogen concentration under the salt stress (150 mM) treatment and 0 EM, reduced 66.5, 54.3, 38.6, 51.4 and 38.1 percent in compared with control treatment, respectively. EM application under this stress conditions caused slowing downtrend aforementioned traits so 44.1, 23.5, 39.7, 44.9 and 28.2% respectively reduction compared to treatment control. By increasing the level of salinity, increased the amount of leaf praline. In general, on the base of this results, it seems that application of EM in pomegranate (shishe kap) orchards can reduce the harmful effects of Salinity.

Shot hole disease, caused by Wilsonomyces carpophilus, is one of the most important disease of stone trees. In order to proper control, the effects of two nano compounds compare to investigated common fungicides on agent of disease was performed in a five replicated in vivo experiment as a randomized complete design with 9 treatments (Mancozeb, Carbendazim, nano copper and nano silver and control treatment). The agent of shot hole isolated from prune and peach trees whit suspicious symptoms, then purified on PAD and WA culture media and was cultured. After the growth of colony was completed in control petri dish, the average of growth was calculated. The results showed Mancozed and Carbendazim fungicides inhibited the mycelia growth at concentrations of 1 and 1.5 per thousand as 18.9, 31.8, 77.2 and 71.5 percent respectively and nano-silver and nano-copper inhibited mycelia growth at concentration whit corresponding values of 40 ppm and 80 ppm, 48.60. 57.63, 81.3 and 34.39 percent. In the case of inhibiting the colony growth, there wasn’t significant difference between control treatment whit Manocozeb and Carbendazim in two concentrations, but the difference between control treatments whit nano-silver was significant and between control treatment with nano copper in 80 ppm the difference was significant while, the difference between nano-copper and nano-silver was significant in l 1% of probability. Therefore, it is concluded that nano-copper and nano-silver are effeactive than common and old fungicides to control shot hole pathogen on stone fruits in vitro condition.

In order to induce genetic variation and produce new hybrid, crosses between different varieties with different flower color have been done. Manual emasculated flowers were pollinated with collected pollen grains. Hand pollination of white flowers female parent with pollen grain of red flower male parent has been carried out in two directions. High dusting self-pollination of red and white color flowers as a control treatment took place. Mean effect of self and cross pollination on number of ovules formation in each ovary through Chi-square test indicated that there was significant differences between them at α=0.05 level. For in vitro nutrition, fertilized ovules were then transferred at different stages of embryos to the culture media. The analysis of collected data for effect of self and cross pollination and different age of embryos on mature embryo germination showed that there is no significant differences between two pollination fashions (cross and self-pollination) at α=0.05 level but there were highly significant differences between age of embryos (21, 30 and 45 days after pollination) at α=0.01 level. Mean comparison through Duncan multiple range test, indicated that highest embryo germination (82.2%) obtained in 30 days old embryos in both pollination fashions (cross and self pollination). Successful acclimatized plantlets transferred to the soilless medium before transfer to the green- house.