IRANIAN JOURNAL OF HORTICULTURAL SCIENCE AND TECHNOLOGY
Year:2003 | Volume:4 | Issue:3-4|Papers Count:10

In order to investigate genetic diversity in the Iranian melon collection, 100 accessions were planted at research field of Seed and Plant Improvement Institute (Gene bank of Iran). The experiment was conducted using simple lattice design. Eight characters including fruit weight, total soluble solids (TSS), seed weight of fruit, fruit netting, number of fruits per plant, fruit hardiness, and flesh and cavity diameter were measured. Analysis of variance showed that for all characters there were significant differences among accessions at 1% probability level, indicating large genetic diversity among accessions. Factor analysis detected that in the first factor, fruit weight, flesh diameter, fruit cavity diameter and fruit netting had the highest factor loadings  and in the second factor, seed weight and fruit  hardness were most important. These factors accounted for 29.92 and 17.05 percent of total variance respectively. Cluster analysis produced nine groups. Each group had special character combinations that make it useful in melon improvement programs.

An experiment was conducted to evaluate the effects of heat treatment and type of packing on storage life and quality of quince fruits. Fruits were heated for 0, 36 and 72 hr at 38°C and packed in polyethylene bags with or without holes and stored at 0°C for 2.5 and 5 mo. The results showed that heat treatment for 36h significantly increased fruit firmness, reduced astringency and weight loss of fruits after 2.5 and 5mo storage at 0°C. Treated fruits, after 5mo storage at 0°C plus 1 week at 20°C were firmer and had higher b-carotene and lower astringency compared with controls.

Two experiments were conducted to evaluate the response of nine onion cultivars to drought and salinity stresses at germination stage and the possibility of improving stress tolerance via seed priming. In the first experiment, the treatments consisted of control (distilled water), solutions containing 25 mM polyethylene glycol 6000 (PEG) to impose drought and 85mM sodium chloride to impose salinity stress. Traits recorded were germination percentage (GP), mean time to germination (MTG), dry weight (DW) of root and shoot and root length (RL). In the second experiment, seeds of: cv. Texas were soaked in 35mM PEG, 200ppm gibberellic acid (GA3) and mixtures of both solutions. Treated seeds were then kept at 10°C for 21 d, thereafter; GP and MTG were recorded under salt and drought at 3 stages (wk 0, wk 1, wk 2). Effects of drought were more severe on GP than salinity, while for the most traits the effects of salinity were more severe. Under stress conditions GP of cvs. Dessex and Milky was very high, while that of cv.PX was very low. Although, significant correlation was found between drought and salinity for GP, some cultivars responded differently. Cvs. Primavera and Savanna were more tolerant to salt than drought. Response of cultivars to MTG was significantly different such that cvs. Primavera and Nastic had the highest and the lowest values for MTG, respectively. Significant differences were also evident between cultivars for SDW, RDW and RL. Cv. Milky had the highest SDW and the longest RL, whereas cv. Texas had the lowest RDW and the smallest RL and cv. PX had the lowest SDW. Results from the second experiment indicated that PEG and EG+GA3 treatments significantly increased GP. Interaction of seed priming and storage period was also significant so that PEG, PEG+GA3 and GA3+PEG treatments significantly increased GP of seeds tested at wk 0; whereas seeds tested at wk1 and wk 2 were only affected by PEG+GA3. Seed priming also reduced MTG compared with control and the effect of PEG was more pronounced. The effectiveness of seed priming treatments was also maintained under stress conditions and storage periods. In order to increase GP and deerease MTG, it is suggested that seeds be treated with PEG or PEG+GA3.

In order to determine the effective factors in rooting of the leafy cuttings of  olive cv. Zard‚ a local Iranian cultivar, the effects of cutting time, position of the cutting on the branch‚ rooting medium and auxin, in a design of split plot at time with four replications and a number of 20 cuttings in each treatment were evaluated. One-year old branches maximum 1 cm in diameter and minimum 1 m in length were prepared on February 4th, April 20th and July 6th and divided into three parts, i.e. the bottom, middle and top. Cuttings prepared from these parts were treated with IBA 2000 and 3000ppm, NAA 50 and 100ppm and a mixture of IBA 1250ppm and NAA 50ppm plus a control of distilled water and were planted in beds of a mixture of washed sand, plus soil and decayed animal manure in equal proportion, and a mixture of 2/3 of washed sand plus 1/6 of soil and 1/6 decayed animal manure. Cuttings were kept in glasshouse equipped with a mist system for 75 days and the effects of the above factors on the number of rooted and grown cuttings, and the number, length, diameter and dry weight of the roots per cutting were recorded. Results from the statistical analysis showed that, on the whole, the best time for the preparation of cuttings was early summer and the cuttings taken from the top section of the branch (soft-wood cuttings), with washed sand as the rooting medium and the IBA treatment at concentrations of 2000 to 3000ppm, were the best treatment.

In the orchard management system and selecting the right location site for sweet cherry, considering chilling requirement is one of the most critical factors. This experiment was conducted in order to determine chilling requirements of 14 sweet cherry cultivars. Shoot samples with enough flower buds were taken from mature sweet cherry trees during autumn period of 2000 growing season prior to chilling period. Shoot samples were kept under 5±1oC for 500, 700, 900 and 1100 hr. Results indicated different chilling requirement for studied cultivars. ‘Selig-Blamarka’, ‘Frosida’ and ‘Germez-e-Rezaeieh’ required less while ‘Mahali-e-Karaj’, ‘Arak’, ‘Napoleon’, ‘Siah-e-Mashhade’, ‘Hajiyosefi’ and ‘Mashhad’ needed higher chilling periods. Furthermore, results showed that terminating chilling requirement for cultivars was performed after gradual cumulative chilling hours under suitable environmental conditions

Effects of polyethylene mulch, planting pattern and irrigation intervals on growth and yield of potato cv. Agria were investigated in 2001. The experiment was carried out as a split plot in a complete randomized block design with three replications, irrigation intervals as main plots (7 and 14 d), planting pattern (common and zigzag) as sub-plots, and mulch (black, transparent polyethylene and bare ground) as sub–sub plots. Weekly irrigation intervals increased main stem diameters, plant fresh and dry weight, main stem number, plant height, tuber weight per plant and yield, but decreased the percent of total soluble salts, very small and small tubers percentages and had no effect on the other traits. Common planting pattern increased only tuber weight per plant. Black and transparent polyethylene mulches increased main stem diameter, plant height, yield, plant fresh and dry weight, tuber weight per plant and the percent of medium and big tubers but decreased the percent of very small and small tubers. Interactions between irrigation intervals and planting pattern on tuber weight per plant were significant. Interactions between irrigation intervals and mulch on plant fresh and dry weight, main stems number yield and tuber weight per plant were significant. Also interaction between planting pattern and mulch had significant effects on tuber weight per plants. The results of this study demonstrate that the black polyethylene mulch, common planting pattern and weekly irrigation intervals were the best treatments.

Citrus is one of the important horticultural crops which are sensitive to salinity. To evaluate the effects of salt stress on accumulation and distribution of Na+ on K+ in three different citrus rootstocks, a study was conducted in a completely randomized design with four replications. In this investigation, three citrus seedling rootstocks including sour orange (Citrus aurantium L.), Taiwanica (Citrus taiwanica L.) and lemon (Citrus limon L.) were treated with four levels of NaCl (0, 20, 40, 60 mM l-1) for three months under greenhouse conditions.Concentration of sodium (Na+) and potassium (K+) were measured in root, leaf and shoot by flame photometric method. The results indicated that with increasing in NaCl levels, concentration of Na+ increased in different parts of all rootstocks whereas the rate of K+ uptake decreased. Concentration of Na+ and K+ in different parts of all rootstocks was different, so that, in sour orange roots, concentration of Na+ was more than Taiwanica and lemon but in sour orange shoots, amount of Na+ was lower than the two other rootstocks. In contrast, in sour orange root, uptake and concentration of K+ was lower but in shoots was higher than the two other rootstocks. Imbalancing of ions and reduction of absorbtion of some ions due to salinity was obvious in this experiment. Excess uptake of Na+ has caused reduction of K+ uptake. K+ is one of the essential elements in plant nutrition and is involved in stomatal opening and enzymatic activities. Deficiency of K+ reduced photosynthesis and transferring of photosynthate to roots and consequently reduced the growth.

Vegetatively propagated ‘M.9’ and ‘M.26’ apple rootstocks are dwarf rootstocks and are widely used in high density apple orchards establishment. The purpose of this research was to study the disinfection treatments, reducing phenolic oxidation and proliferating ‘M.9’ and ‘M.26’ explants under in vitro conditions. Plant materials used in this experiment were taken from spring shoots of ‘M.26’ and summer shoots of ‘M.9’. For disinfection, plant materials were dipped into 70% ethanol for 30 s followed by immersion in various concentrations of chlorox or mercuric chloroide and the best results were obtained with 0.1% mercuric chloroide with 3 and 5 min of immersion time for ‘M.26’ and ‘M.9’, respectively. Explants were cultured on MS medium (for ‘M.9’) and MS with the vitamins of B5 medium (for ‘M.26’) containing 2 and 1 mg.1-1 BA,  respectively, and 0.1 mg.1-1 GA3 for both rootstocks. In order to prevent phenolic oxidation, several methods were used and the best results were obtained with incubating newly cultured explants in a refrigerator for 6 d. In proliferation stage, effect of BA and Kinetin (Kin) (separately or in combinations) were examined. Results showed that Kin had no effect on proliferation and combinations of BA and Kin improved shoot proliferation rate compared to BA alone. In ‘M.9’ rootstock, highest multiplication rate and number of shoots≥5 mm were obtained with 2+0.1 and 1.5+1 mg l-1 BA+Kin, respectinely. In ‘M.26’ rootstock, highest proliferation rate were obtained with 0.75+05 mg.l-1 BA+Kin. However, these combinations were not significantly differentet at 5% level of probability in some treatments.