نشریه تولیدات گیاهی
سال سی و پنجم شماره 2 (تابستان 1391)

Sugarcane is a tropical plant and a member of the poaceae family which, despite its low tolerance to cultivation in chilly climates shows no resistance to planing them in subtropical region. In order to evaluate different management methods in sugarcane fields damaged by cooling and yield reduction, a completely randomized block design (RCBD) was carried out with 3 replications and the 4 treatments (CP 48-103 cultivar) in 2008-2009 in Amirkabir Sugar cane company in the south of Ahvaz. The treatments were cutting of plant residue (Base Cutting), burning, application of Cytokinins hormone, and control. The results showed that the treatments had no significant differences in stalks numbers while the treatments of hormones and Base Cutting were significant in height, and the Base Cutting treatment had a maximum height. The Base Cutting, Burning and hormones treatments had significant differences in chlorophyll rate of leaf blade. Qualitative properties such as Recoverable Sugar (R.S) marked no significant differences between other treatments. The sugarcane yield showed a significant difference, where the treatment of Base Cutting had highest yield, but in the case of sugar yield production there were no differences between the treatments. Control, cutting of plant residue, burning and application cytokinins hormone treatments yield were 55375, 57625,56562 and 49125 kg/ha cane and 4651, 4955, 4049 and 4092 kg/ha sugar, respectively. Results indicated that when chilling occurring injury, the suitable economic method is leaving the injured fields without any field practices.

Evaluation ofkaryotype¡ ploidy levels and chromosome numbers of daffodil (Narcissus sp.) plants was carried out on collected endemic genotypes from Southern Khorasan¡ Khouzestan¡ Kohgiloye – Boyerahmad¡ Fars¡ Mazandaran¡ Golestan provinces and exotic genotypes. The mitotic study karyotype and morphological characteristics of daffodils chromosomes was conducted on the meristematic cells of root tips from bulb. Initially the root tips were pretreated comparable with 8-hydroxyquinoline and ice water. Then they were fixed in ethanol: acetic acid (3:1) solution¡ hydrolyzed in HCl and stained with aceto-orsein. Three metaphase plates were used to analyze karyotype parameters of each genotype. OR-banding was carried out according to conventional methods. Chromosome numbers showed ploidy levels variation between genotypes. There was a direct relationship between chromosome number and ploidy levels of genotypes. Basic chromosome numbers of endemic and exotic populations were 10 and 7¡ respectively. Meskinak-e-Behbahan and meskinak-e-Ahvaz varieties were diploid 2n=2x=20 with karyotypic formula: 4m뻖¡ others were triploid 2n=3x=30 with 7m�¡ white Holandi`s daffodil was tetraploid 2n=4x=28 with 2m뻖; others were triploid 2n=3x=21 with 1m뻖. Karyotype evaluation indicated that size and form of chromosomes were different. Also¡ ploidy levels were confirmed by flow cytometry method.

The genetic structure of agronomic traits has the most important role in determination of breeding methodology. Generation means analysis and QTL mapping refers to effective methods for determination of gene type and action. In order to investigate the genetic structure of agronomic traits of Gharib × Khazar via means analysis, six basic generations in three replications as randomized complete block design were cultivated at Gonbad Higher Education Center in 2008. At the same time, in order to map agronomic traits, 20 plants of 192 F3 families and parents were planted. The results showed gene controlling of plant height, panicle length and biomass indicated over dominance, grain number, branches number, days to flowering, panicle extraction and flag leaf length showed partial dominance. Significant additive effects were detected for grain number, branches number, days to heading, plant height and panicle extraction. Therefore, the selection method is useful for improving these traits. The three paramedic models were detected for branches number, plant height, panicle length, panicle extraction, days to heading, panicle extraction and flag leaf length and width. Mapping of agronomic traits showed that qHD-1b, qPL-12, qNP-2, qDWS-8, qWFL7, qWP1, qWP-11a and qWP11b explained more then 20 percent of total phenotypic variation. The comparison of the two methods showed that, with the aid of selection for some QTLs such as qHD1b, can be used for decreasing days.

Two apple cultivars (Golden Delicious and Red Delicious) were irradiated with UV-C (254nm) for 0, 20, 40 and 60 minutes to evaluate fruit quality and storage life. Evaluated characteristics included firmness, total soluble solids (TSS), pH, titratable acidity (TA), ascorbic acid, weight loss, decay and visible quality recorded at beginning, mid and end of the storage. The experiment was carried out with a factorial experiment in completely randomized design with four replications. The results indicated that UV-C treatments were significant on evaluated characteristics during and at the end of the storage. But decay and visible quality were not significant between cultivars. Also interaction of cultivar and UV-C treatment exerted no significant effect on measuring factors. According to the obtained results, UV-C radiation with 40 and 60 minutes treatment was more effective on evaluated characteristics.

Each year, due to postharvest losses, a significant proportion of horticultural products doe's not reach consumers. One of the postharvest losses factors is the contamination of fruits and vegetables by different pathogens i.e. fungi and bacteria. Currently, different synthetic fungicides are used to control these pathogens. Various problems related to the use of these compounds the development of alternative safe methods. Using SO2 releasing sachets is an inexpensive and low risk method that could fumigate fruits during storage and marketing by releasing gas continuously. In this research, the effects of using SO2 releasing sachets at different concentrations (0, 79, 132 and 184 mM sodium metabisulphite) on the physicochemical changes of tomato fruit cv. “Chef” were studied during the storage period (0, 3, 6, 9 and 12 days) at 5°C. Different quality parameters including weight loss, firmness, lycopen content, Vit C, titratable acidity, total soluble solids, phenolics content, antioxidant capacity and decay percent were evaluated. The results showed that treatment with SO2 releasing sachets effectively reduced the decay incidence and increased the phenolic compounds concentration. Also, SO2 gas had no negative effects on fruit red color produced by lycopen pigment. Sodium metabisulphite at 79 and 132 mM concentrations showed the most desirable effect on maintaining color and Botrytis decay control at different time intervals.

In order to study the effect of plant density on the yield of four sweet corn hybrids, this experiment was conducted at Yasouj Agricultural and Natural Resource Research Center in 2005. The experiment treatments were arranged factorialy in a randomized complete blocks design with three replications. The factors of the experiment consist of four sweet corn hybrids (Powerhous, Harvest gold, Chiss and Shiker) and three plant densities (6, 7 and 8 plant m-2). The results showed that the interaction between plant density and hybrid on fresh ear yield and canned and harvest index was significant. The highest fresh ear yield was 2734 g m-2 at density of 6 plant m-2 in Harvest gold hybrid and the lowest fresh ear yield was 1742 g m-2 at density of 8 plant m-2 in Chiss hybrid. Maximum canned yield was 1453 g m-2 at density of 6 plant m-2 in Harvest gold and Shiker hybrids and the lowest was 797 g m-2 at density of 8 plant m-2 in Chiss hybrid. By increasing plant density, forage protein in all hybrids decreased in the same trend. In general, hybrids of Harvest gold and Shiker and also density of 6 plant m-2 are introduced as the best treatment.

To determine the correlated traits to grain yield in rapeseed, eight rapeseed cultivars were planted using randomized complete block design with three replications in Rice Research Institute of Iran, Rasht, Iran, during 2005-6 and 15 traits including sowing to rosette period. Analysis of variance showed that significant differences among varieties for studied traits, indicating the existence of high genetic variation among varieties. Grain yield had a significant positive correlation with 1000-grain weight and flowering to ripening period and had a significant negative correlation with number of grains per silique and silique length. Results of stepwise regression analysis of grain yield showed that traits 1000-grain weight, number of grain per silique, number of secondary stem and height of the first silique from soil surface had the highest effect on grain yield and 98% of grain yield variation was attributed. Correlation coefficients analysis to path coefficients analysis showed that 1000-grain weight has the highest direct effect on grain yield relation to other traits, but the indirect effects of this trait were unimportant through other traits. Factor analysis showed that 79.275 percent of total variations were determined by three main and independent factors namely yield components, plant type and vegetative growth and the most important traits as a selection index to improve grain yield were 1000-grain weight, number of grain per silique and flowering to ripening period, respectively, placed in first factor with grain yield. Biplot charts derived from the factor analysis and grouping traits using cluster analysis confirmed this result and the above traits were introduced as the most important traits to improve grain yield in rapeseed.

In order to study the effect of planting date on phonological stages and quantity traits of four cultivars of winter rapeseed, an experiment was carried out in 2008-2009 at the research field of Agriculture Research Station of Boyerahmad. The experiment was carried out in using factorial with randomized complete block design and four replications. Four planting dates (September 12, September 22, October 2 and October 12) as a first factor and four cultivars (Zarfam, Okapi, Elite and SLM-046) as second factors were used. The results of this study showed significant differences between the occurrence date of cultivars and planting dates with one percent level of probability. Delay in planting increased the process of planting and completion rosette, but decreased rosette periodic duration, during flowering and planting to maturity. Delaying in canola planting caused the interaction of grain filling and oil accumulation with higher temperature with decreased grain, oil and protein yield. Elite and Zarfam cultivars, due to faster completion of their rosette, finished over wintering with stronger rosette and began their regrowth at end of cold season earlier. Therefore, the reproductive stages of these cultivars were encountered with better weather conditions and also led to higher performance. In general, at September 12 planting date, Elite cultivar and at delay planting, Zarfam cultivar were superiors over other cultivars.

In order to determine the most important traits influencing root yield and sugar content of autumn-sown sugar beet monogerm O-type lines, 49 genotypes (O-types and hybrids) were evaluated in a triple lattice design with three replicates at Safiabad Agricultural Research Center, Dezful, Iran in 2008-2009. Following an analysis of variance, statistical analyses such as simple correlation coefficients among the traits were administered on treatment means. Factor analysis divided all the studied parameters into five factors: white sugar content, yield, root morphological characteristics, resistance to bolting and Cercospora leaf spot. Root diameter, resistance to Cercospora, crown height, root shape, alpha-amino nitrogen, potassium and extraction coefficient of sugar were identified as the most important traits in stepwise regression analysis for root yield as the dependent variable. In forward regression analysis for sugar content as the dependent variable, the most important traits were found to be molassed sugar, crown height and resistance to bolting, respectively. Path analysis indicated that root diameter, root shape and alpha-amino nitrogen had direct positive effects and cercospora resistance, crown height, potassium and white sugar content had direct negative effects on root yield. Also, the direct effect of crown height on sugar content was positive and that of molassed sugar and cercospora resistance was negative. Cluster analysis demonstrated that the genotypes of cluster 2 were superior in the traits affecting root yield, whereas the genotypes of cluster 1 were superior with respect to the traits influencing white sugar content and extraction coefficient of sugar. Therefore, the genotypes of the latter cluster could be used to increase white sugar content and extraction coefficient of sugar and hence decrease the impurities such as sodium, potassium and alpha amino nitrogen.