مجله تولید و فرآوری محصولات زراعی و باغی
سال سوم شماره 3 (پیاپی 59، پاییز 1392)

Drought is one of the major factors limiting crop production in Iran. Twenty Iranian wheat cultivars with wide range of sensitivity to drought, including 18 varieties of bread wheat and two varieties of durum wheat were used in two separate field experiments in 2009-2010 at the Experimental Station of College of Agricultural in Shiraz University. Each experiment was conducted as a randomized complete block design with three replications. The moisture level in one of the experiments was optimum (100% field capacity) while the second experiment was conducted under drought stress (45% field capacity). Several biochemical components including antioxidant enzymes and hydrogen peroxide and some physiological traits were analyzed in the two conditions. Drought stress significantly increased antioxidant activity at the grain filling stage. Superoxide dismutase activity showed the highest increase. Lipid peroxidation, hydrogen peroxide, electrolyte leakage and cell death increased significantly under drought condition, however membrane stability index decreased. Resistant cultivars showed the highest antioxidant activity and the lowest lipid peroxidation, hydrogen peroxide, and electrolyte leakage. This trend was reversed in the susceptible cultivars. Peroxidase and superoxide dismutase had a significant correlation with yield stability index. Hydrogen peroxide and cell membrane stability indices showed the highest correlation with yield stability index. Also Pishtaz and Alamut were selected respectively as the most resistance and susceptible cultivars.

Improvement of resource use efficiency is a basic approach for sustainable agriculture. Applying intercropping systems, in which resources such as water, radiation and nutrients are used optimally, is one of these strategies. In order to evaluate radiation absorption and use efficiency in additive intercropping of maize-bean, an experiment was carried out in 2010, based on completely randomized blocks design with three replications, at Research Farm of Zanjan University. Treatments included different ratios of additive intercropping system (sowing 20, 40, 60 and 80% of common bean optimum density + optimum density of maize) and monoculture of these crops. Dry matter and leaf area of both crops were measured during the growth period. Results showed that the absorbed radiation by canopy of maize-bean intercropping in all treatments was higher than the monoculture of maize and bean, because the surface of canopy increases to absorb radiation. for intercropping system and result in more absorption of radiation compared to monoculture. The values of LERPAR were more than 1 in all intercropping treatments, which indicates the advantage of intercropping cultivation in comparison with monoculture system based on radiation absorption. Higher values of radiation use efficiency for maize and bean under intercropping system in comparison with monoculture of these crops confirmed the optimum use of radiation resource in intercropping system. Regarding the efficiency of radiation absorption by different intercropping treatments, the additive cultivation of 60% bean with 100% maize was identified as the best cropping pattern.

In order to investigate the effect of planting date on yield and yield components of grain sorghum cultivars, a factorial experiment was conducted at Research Farm of Yasouj University, in 2010, based on randomized complete blocks design and three replications. The studied factors included nine sorghum cultivars (SOR 1003, SOR 834, SOR 808, SOR 1008, SOR 1011, SOR 1009, SOR 1006, SOR 857 and SOR 838) and three planting dates (20 May and 5 and 20 June). The results showed that the interaction effects of cultivar and planting date on yield and yield components and some of the studied physiologic and morphologic traits were significant (P≤0.01). The highest yield (863 g/m2), chlorophyll content, panicle length and number of grains per panicle (2191) were obtained from the planting date of 5 June in SOR 834 cultivar. The highest number of fertile tillers (10), carotenoid and chlorophyll b was produced by SOR 1003 cultivar and planting dates of 5 June, 20 June and 20 May, respectively. The SOR 834 cultivar and planting date of 20 June produced the highest 1000-seed weight (28.55 g). According to the results, planting date of 5 June and SOR 834 sorghum cultivar is recommendable in Yasouj region and similar agro-climatic conditions.

In order to investigate the effect of nitrogen (N) fertilizer and transplanting date (TD) on yield, yield components and stem lodging of rice (Oryza sativa), a two-year study (2007-2008) was carried out in Fozveh Research Station, Agricultural and Natural Resources Research Center of Isfahan, Iran, using split plots, based on randomized complete blocks design with three replications. Four N fertilizer levels (control, 126, 180 and 234 kg/ha N) were assigned as the main factor and three TDs (late May, early June and late June) were assigned the sub-factor. The results showed that application of 126 and 180 kg/ha N caused 13 and 17% increase in the yield, respectively, as compared to control. But, the 234 kg/ha N treatment had similar yield to control treatment (6672 kg/ha), due to severe stem lodging (45%). The highest agronomic N efficiency (17.7 kg of grain produced per kg of consumed N) was obtained in the 180 kg/ha N treatment, and this was not significantly different from the 126 kg/ha N treatment. Number of panicles per m2 in 126 and 180 kg/ha N treatments, was increased by 16 and 24%, respectively, over the control treatment. Transplanting the seedlings to the main field in late May and early June produced a yield of 7391 and 7831 kg/ha, respectively. Although the stem lodging in late June was lower than the other two TDs, but grain yield was reduced by 29 and 37% with respect to late May and early June, respectively. The results showed that application of 126 kg/ha N and transplanting the seedlings in late June is recommendable for Sazandegi rice cultivar in Isfahan region.

In order to investigate the effects of sowing date on yield and some agronomic traits of six forage maize hybrids, two experiments were conducted in 2009 in two locations including Rasht and Fuman. The experimental design was randomized complete blocks with factorial arrangement and three replications. Treatments consisted of three levels of sowing date (31 May, 13 and 26 June) and six maize hybrids of early maturing (SC301 and DC370), medium maturing (SC400 and SC647) and late maturing (SC700 and SC704). The measured plant characteristics were fresh and dry forage yield, leaf dry weight, ratio of leaf dry weight to plant dry weight, ratio of stem dry weight to plant dry weight, ear dry weight, ratio of ear dry weight to plant dry weight and leaf to stem ratio. Results showed that forage yields for different planting dates were significantly different at the two locations.; The 13 June planting date in Fuman region and 26 June in Rasht region were better than other dates. Maximum dry forage yields for two locations of Fuman and Rasht in SC700 were 18862 and 23565 kg/ha dry weight (fresh weight of 90199 and 82642 kg/ha, respectively). The results of this experiment indicated that if SC700 hybrid is sowed at optimum date, it will produce more dry weight than other hybrids.

In order to evaluate the effect of different periods of weed interference and weed control on plant height, seed yield and yield components of common bean, an experiment was conducted at the Agricultural and Natural Resources Research Center of Hamadan, Iran, in 2011. The experiment was a randomized complete blocks design with 3 replications. Treatments included two groups of weed interference and weed control. In the first group, weeds competed with crops until 10, 20, 30, 40 and 50 days after plant emergence. The second group included weed control until the aforementioned periods. Furthermore, two treatments including full season weed-free and full season weed-infested were considered as control plots. Results showed that weed dry matter had an ascending trend in weed interference treatments, while, it showed a descending trend in weed-free treatments. As the weed competition was increased, plant height showed a decreasing trend during the growing season. Number of pods per plant and number of seeds per pod in the treatments had significant differences at 1% and 5% probability levels, respectively; but they had no significant effect on 100-seed weight. Grain yield was significantly affected by the treatments (P≤ 0.01). Increasing duration of weed interference reduced the grain yield. The lowest grain yield (1168.3 kg/ha) was observed in the weed-infested plots. In contrast, increasing duration of the weed control, increased the grain yield. Maximum seed yield (2869.1 kg/ha) was produced by weed-free control treatment.

In order to maintain sustainable agriculture and prevent excessive use of chemical fertilizers, supplying part of the plant needs by organic fertilizers is necessary. In this respect, effects of nitrogen (N) source and rate on yield and yield components of forage sorghum was evaluated as a factorial experiment arranged in randomized complete blocks design with three replications at the Research Farm of Shahrekord University in 2010. Treatments consisted of three N sources (urea fertilizer, cow manure and equal combination of urea fertilizer + cow manure) and three N levels)80, 160 and 240 kg/ha N, equivalent to 174, 348 and 522 kg/ha urea and 26.2, 52.5 and 78.7 Mg/ha of cow manure and equal combination of urea fertilizer + cow manure at each nitrogen level, respectively). The results showed that increase of N utilization, with increase in leaf, stem and panicle weights and stem diameter, caused a linear increase of forage yield in urea fertilizer and cow manure treatments and a quadratic increase in the combined fertilizer. The highest leaf, stem and panicle weight (600, 3789 and 823 g/m2) and also fresh forage yield (44 Mg/ha) were observed in 240 kg/ha N treatment in combined treatment. But, there was no significant difference in forage yield between this treatment and the 160 kg/ha N treatment. Overall, the results indicated that the potential of sorghum production can be increased by conjunctive use of animal manure and chemical fertilizers, even in low levels of these fertilizers, or low-input agriculture.

A great part of lands under corn cultivation are affected by different levels of salt stress. This study was conducted in order to determine the effect of different levels of salt stress on yield and some physiological characteristics of corn plants. Two experiments were carried out in greenhouse (a factorial based on randomized complete blocks design with 3 replications), and field (a split plot based on randomized complete blocks design with 3 replications) at College of Agriculture, Shahid Bahonar University, Kerman, Iran. Treatments included 4 levels of irrigation water salinity (2, 4, 6 and 8 dS/m) and seven corn hybrids (SC-700, SC-500, SC-404, SC-704, SC-647, SC-301 and Maxima). During the growing period, leaf samples were taken from greenhouse-grown plants and their physiological characteristics such as chlorophyll fluorescence and ion leakage were measured. Grain yield was determined in the field plots. Results revealed that salt stress decreases chlorophyll index and photochemical efficiency of PSII of leaf tissues due to increasing original fluorescence (FO) and decreasing maximum fluorescence (Fm). Meanwhile, increasing the salt stress increased ion leakage. Results also showed that high salinity decreased the grain yield. The highest grain yield was obtained in plots with the lowest salinity level. Correlation coefficients showed that Fo and Fm parameters dont have significant correlation with salinity. While, Fv/Fm index had a positive relationship with salinity tolerance. The highest chlorophyll index, photochemical efficiency of PSII, membrane stability and grain yield was obtained for SC-704 hybrid. Therefore, it was the most tolerant hybrid and was recommended as a resistant cultivar against salinity stress.

One component of integrated weed management is use of cultivars with high competitive ability against weeds. Balance between competitiveness and productivity of rice under condition of presence or absence of weeds, is complicated the breeding of rice cultivars to increase competitiveness against weeds. Path coefficient analysis has been widely used in crop breeding to determine the nature of relationships between the grain yield (GY) and its contributing components. To study the weed-suppressive ability by rice, an experimental was conducted in a randomized complete block design with four replications in Chprsr, Tonekabon Rice Research Station at 2009. The experimental treatments include seven varieties (Daylamani, Khazar, Sepeedrud, Neamat, Dorfak, Fajr and Shiroodi) and three lines (830, 841 and 843) of rice that were cultured in the presence of barnyard grass. The results of path analysis showed ability withstands competition (AWC), thousand grain weight (THGW), fertile tiller number m-2 (FT), filled grain number panicle-1 (FG) and competitive index (CI) as the first-order variables for GY. The traits such as specific leaf area of rice at 25 days after transplanting (Rsla25), ear length (EL), Filled grain percentage (FGP), specific leaf area of rice at heading stage (RslaHD) were as the second-order variables for GY and influenced positively this response variable. Dry weight of barnyard grass biomass was negatively correlated with CI and RslaHD. However, these traits have a positive effect on grain yield, but fertile tiller number and specific leaf area at heading stage are measurable before maturity of grain. Thus, select of cultivar with high grain yield is possible before heading of grain, through these two traits. The variety of Shiroodi and line of 843 with highest value of specific leaf area at 25 days after transplanting and heading stage, high ability withstands competition and competitive index have a high capacity to compete with barnyard grass and can be considered as a suitable cultivar in selection processes and are also used as crosses parents.

Traits related to seed quality have an important role in production of durum wheat. To estimate the heritability of protein content, semolina content, Zeleny number, seed hardness, SDS, dry and fresh gluten content, gluten index, and also to investigate the relationship of these traits in durum wheat, a recombinant inbred lines (RILs) population including 94 recombinant inbred lines (F10), two parents (Ac. Navigator and G9580B-FE1C) and four controls (Diper, Preion and PI10235 varieties and a local variety “Ajr”) were evaluated. This experiment was carried out in the Research Farm of Shahrekord University, Shahrekord, Iran, using a triple lattice design.. Results showed that frequency distribution for gluten index was bimodal and for the rest of the traits was normal. This indicated the two-genes control and quantitative inheritance of these traits in the population,respectively. Transgressive segregation was observed for all the traits. The calculated heritability for protein content, seed hardness, SDS and semolina content was in the low range of 11.4-24.7%. For fresh and dry gluten and Zeleny number, it was 45, 36.2 and 37.1%, respectively. For gluten index, it was high (76.6%). The genetic correlation coefficient between protein content and Zeleny number was positive and high (r= 0.98), which indicates the suitability of this trait as a criterion for protein content. The results of path analysis for semolina, as the main feature in pasta production, based on genetic correlation coefficients, showed that the highest negative direct effect was related to Zeleny number the highest positive effect was related to protein content, which indicated the importance of these traits in explaining the semolina yield.

In many areas, low temperature is an important environmental limiting factor in production and distribution of horticultural trees and plants. This study was conducted to study the frost tolerance of main local clones of cornelian cherry in Tarom Sofla region, Qazvin, Iran. Cold treatments at 5 levels (+4, +2, 0, -2 and -4 ˚C) at two cooling periods (3 and 5 hours) were arranged as a factorial experiment, based on completely randomized design with 4 replications, at flowering stage of Golabie Siah (black pear) and Paeizi (autumn) clones in 2009-2010. For each treatment, the electrical conductivity (EC) and acidity (pH) were measured just after shaking (t=0), every 3 hours in the first 24 hours, and once daily in the 2nd to 8th day. After a week, the samples were autoclaved at 105˚C for 4 minutes and the changes were recorded. Results showed that the range of EC in flower was 92.2-846.2 µS/cm, and the range of pH varied from 6.4 to 7.7. Based on the results, the effect of frost intensity on EC changes was ascending, and on pH was slowly ascending and sometimes fixed. The highest value of EC due to destruction of tissues, as an index of frost damage of the flower, was obtained at +4 ˚C. Therefore, tolerance range of cornelian cherry flower has been estimated to be more than +4 ˚C.

Drought stress has an important role in yield reduction of crops. To investigate the effects of applying zeolite hydrogel (as a superabsorbent) in reduction of adverse effects of drought stress on chlorophyll content, nitrogen, growth indices and their relationships with quantitative and qualitative yield of pearl millet (cv. Nitrifeed), a split plot experiment (in space and time), based on randomized complete blocks design with three replications, was carried out at Research Farm of Shahid Bahonar University, Kerman, Iran, in 2011. Treatments included drought stress at four levels (irrigation at 40, 60, 80 and 100% of field capacity) as the main factor and superabsorbent hydrogel at three levels (0, 150 and 300 kg/ha) as the sub-factor. Results revealed that there was a positive and significant correlation (r = 0.97**) between chlorophyll content and leaf nitrogen percentage. Also, significant correlation was observed between these traits and forage fresh and dry weight of forage, protein yield and raw fiber percentage of the forage. As drought stress increased, the measured traits showed a descending trend. The superabsorbent polymer increased the fresh and dry weight of forage, growth indices and qualitative traits of pearl millet. Mean fresh weight of forage, chlorophyll content, protein content and percentage of fiber showed no significant difference between 100% and 80% irrigation levels. Superabsorbent application led to 20% water saving. Therefore, it can be said that superabsorbent hydrogel application under drought stress will improve yield, qualitative traits and growth indices of pearl millet through increasing soil water holding capacity, reducing nutrient leaching, fast and optimal growth of roots and better soil aeration.

In order to study the effect of terminal drought stress on yield and yield components and some physiological traits of wheat genotypes, a field experiment was conducted at the Research Farm of Agricultural College of Shiraz University during 2010-11 growing season in a split plot arrangement based on randomized complete block design with three replications. Main plots were assigned to irrigation treatment and the sub plots to sixteen wheat genotypes. Post anthesis cutting irrigation caused significant reduction in grain yield (GY), biological yield (BY), harvest index (HI), canopy temperature depression (CTD), grain number per spike, 1000 grain weight and relative water content (RWC). Under normal irrigation conditions, the highest grain yield was obtained from Zarrin cultivar, whereas, under drought stress conditions, the highest grain yield was obtained from Tabasi cultivar. The trait most sensitive to water stress was grain yield (mean reduction 51.6% compared to control) followed by harvest index (mean reduction 37.2% compared to control). Correlation coefficient results showed that under normal irrigation conditions the highest correlation was between grain yield and biological yield (0.844*) and under stress conditions was found between grain yield and grain number per spike (0.895**), CTD (0.771**) and 1000 Grain weight (0.689**). Evaluating of CTD trend under stress conditions showed that by passing time from applying cutting irrigation, canopy temperature (CT) gradually increases due to water unavailability. The most reduction in grain and biological yield under drought stress was observed in C-85-7 genotype, whereas, cv. Shiraz with the least reduction in these two components, was found a drought tolerant and yield stability cultivar. At both irrigation treatments, there was a positive correlation between grain yield and CTD; therefore, CTD may be a suitable index for selecting late-season water stress tolerant wheat cultivars.

This pot experiment was carried out to investigate the efficacy of certain Zn-amino chelates, i.e. Zn-glycine [Zn(Gly)2], Zn-arginine [Zn(Arg)2] and Zn-histidine [Zn(His)2] in supplying zinc for wheat was compared with a commercial Zn-sulfate fertilizer. Three wheat cultivars, differing in Zn-efficiency, including Back Cross Rowshan, Kavir and Durum were planted at Research Greenhouse of Isfahan University of Technology, Isfahan, Iran, in 2010. Fertilizer treatments were applied at planting and tillering stages, with 20 mg Zn per kg soil. Results showed that soil application of Zn fertilizers increased shoot Zn content of all three wheat cultivars in comparison with control (no addition of Zn) treatment. Shoot Zn content of Durum cultivar treated with Zn(Gly)2 was 33.3% higher than Zn-sulfate. The effect of Zn-amino chelates on activity of catalase (CAT) and ascorbate proxidase (APX) was dependent on the amino chelate type and wheat cultivar. Zinc-amino chelates resulted in increase of CAT activity in the leaves of Kavir and Back Cross Rowshan cultivars, while they were ineffective in Durum cultivar. In all three wheat cultivars, leaf activity of APX was also significantly increased by Zn(His)2 and Zn(Arg)2 over the Zn-sulfate treatment. According to the results of the present study, Zn-amino chelates could play more effective role in improving plant Zn nutrition status and increasing yield and seed quality of wheat by increasing Zn uptake and activities of CAT and APX enzymes.

Strawberry (Fragaria×ananassa) has tasteful, fragrant and nutritious fruits. But, because of delicate texture and high metabolic activities of the fruits at maturity, are very sensitive and easily decayed, and thus have short shelflife. Ethylene is one of the main causes of postharvest fruit losses, which could reduce the shelflife of strawberry. Therefore, an experiment was carried out to examine the effect of 1 µL/L 1-MCP treatment and low-pressure air pretreatment at 0.2 atm in 2 hours on apparent and physicochemical characteristics of strawberry fruit, cultivar Camarossa, during storage in cold store. The study was performed as split plots in time, based on complete randomized design with 3 replications. The results showed that the highest marketability (90%), fruit firmness (7.95 N), titrable organic acids (1.15 g/100 cc), vitamin C (78.13 mg/100 cc) and total soluble solids (10.48 %) and the lowest amount of apparent decay (13.3 %), acidity (3.63) and taste index (9.04) were obtained in 1-MCP and low-pressure air treatments, which shows the effect of treatments on reducing the rate of biochemical variations in fruit texture. Correlation coefficients between all treatments were significant (P≤0.01). Meanwhile, the positive effect of 1-MCP on appearance and studied physicochemical characteristics was more than low-pressure air pretreatment. Even, the combination of these two treatments had no significant difference with 1-MCp treatment alone. In general, this observation depicts the more positive and significant effect of 1-MCP treatment in delaying the maturity and improving the qualitative traits of strawberry fruits after being stored in cold storage.

Phenology, as one of the most important subjects of ecology, is the study of periodic plant life cycle events and how these are influenced by variations in climate and ecological conditions. In this research, phonological observations of 5 species (Prunus dulcis, Prunus avium, Prunus armeniaca, Pyrus communis, Prunus domestica) were studied in Iranian orchard of National Botanical Garden of Iran during the years 2004-2008. Ten trees were selected for each species and leaf, flower and fruit phenology were recorded from second decade of February to end decade of November. Occurrence time of phenomena was converted to its interval from first day of the year. Statistical analysis of occurrence time of phenomena showed that there are significant differences between the studied species. Soonest and latest occurrence time of phenomena and their sustainability were observed in P. duclis and P. avium, respectively. Based on study of correlation between climate factors (temperature and precipitation) and occurrence time of phenomena, significant correlations were found in some species.

To evaluate the tolerance to salinity in almond, this factorial experiment was conducted based on completely randomized block design with three replications in greenhouse of Agricultural and Natural Resources Research Center in East Azerbaijan province. The first factor included almond cultivars (Mangha, Nonpareil, Eskandar, Araz and Sahand), and the second factor was salinity levels (electrical conductivity of 0, 2, 4, 8 and 16 dS/m). In this experiment, the plant height, fresh and dry weight of leaves, chlorophyll index and concentration of nitrogen, sodium, potassium, chloride, calcium and magnesium were measured. The results showed that the highest plant height belonged to Eskandar and Sahand cultivars. With increasing the salinity level, nitrogen concentration of the leaves decreased. Leaves of Mangha cultivar had the highest chlorine content. Although calcium concentrations of the leaves in various salinity levels were in the same statistical group, but calcium concentration was increased in higher salinity levels. Araz cultivar had the highest concentration of magnesium in its leaves. Interaction of salinity × cultivar for phosphorus content showed that Araz cultivar produced the highest phosphorus content in its leaves at salinity level of 16 dS/m. Statistical results of sodium to potassium ratio, which is an index for resistance to salinity, showed that Araz was the most tolerant almond cultivar against salinity.