IRANIAN JOURNAL OF HORTICULTURAL SCIENCE AND TECHNOLOGY
Year:2001 | Volume:2 | Issue:1-2|Papers Count:9

Rapid propagation of potato by stem, sprout and single-node cuttings is used in the many research programs for production of certified disease-free seed potato. This research was conducted in two successive years (1997 and 1998) in the greenhouse of the Department of Horticulture, College of Agriculture, Shiraz University using three cultivars, namely 'Marfona', 'Moren' and 'Picaso'. Stem cuttings were harvsted from axillary shoots.After applying necessary pretreatments on tubers of three potato cultivars, terminal and side-buds were used for sprout cutting. In single-node propagation method, when shoots of stock plants had 4 to 5 leaves, they were cut, so that, each leaf with it's axial bud was harvested for cutting. All three types of cuttings were treated  with concentrations of 0 and 250 ppm naphthaleneacetic acid (NAA) for 2 min. In all three propagation methods, cuttings were placed in a sand culture medium. The highest rooting percentage (%98.3) was obtained with sprout cuttings which were not significantly different compared to stem cuttings. However, these two propagation methods were significantly different with single-node method. Rooting rate was severely affected by the method of propagation. In sprout cuttings, rooting was performed after 4.27 d which was significantly different with single-node (14.83 d). Concentration of 250 NAA did not affect rooting percentage in sprout and stem cuttings but in single-node cuttings, NAA increased rooting percentage from 55.63 to 91.60%. In all three propagation methods, NAA increased the number of roots which was significantly different competed to control. Application of NAA increased dry and fresh weights of roots. Rooting percentage, rooting time and number of roots were not significantly affected by cultivar. However, cultivar significantly affected dry and fresh weights of roots. 'Marfona' had significantly highest dry and fresh weights when compared with other cultivars. The means of both years were used for statistical analysis. All experiments were conducted in a completely randomized design with a factorial arrangement, having four replications. Means were compared using Duncan's new multiple range test (DNMRT).

In order to induce ripening and reduce susceptibility of dates to rain damage in Khesht and Konar- Takhteh regions an experiment was conducted to evaluate the effects of benzyladenine, ethephon, sodium chloride and acetic acid on early ripening in 'Kabkab' date.The experiment was designed as a complete factorial arranged in a completely randomized block design with four replicates. Twenty eight 'Kabkab' palms were selected and benzyladenine was applied two weeks after fruit set. Ethepon (0, 1000, 2000 mgl-1) sodium chloride (0, 1.5%, 3%) and acetic acid (0, 2%, 4%) treatments were applied at the begining of the Khalal stage and repeated two weeks later. The results of this experiment showed that ethephon (1000, 2000 mg mgl-1) and acetic acid (2% , 4%) were more effective on early and uniform ripening of date fruits than sodium chloride. Benzyl adenine significantly increased fruit size, but delayed the ripening of fruits. Total soluble solids were affected by chemical treatments but the pH was not affected. Ethephon and especially acetic acid induced ripening two weeks earlier than control.

Experiments were conducted, from 1997 to 1999, to investigate the effects of various treatments on sexual and asexual propagation of judastree (CercissiliquastrulLll.). In sexual propagation, seeds were scarified by concentrated sulfuric acid for 0, 30, 45 and 60 min. For stratification treatment, seeds were kept for 0, 15, 30 and 45 d at 3-5°C. Also to evaluate the effects of gibberellic acid treatments, seeds were soaked in solutions of 0, 125, 250 and 500 mg mgl-1 for 24 hr. In asexual propagation, cuttings were treated with naphthalene acetic acid at concentrations of 0, 2500, 5000, 7500 and 10000 mg rl or with indolebutyric acid at concentrations of 0, 4000, 8000, 12000 and 16000 mgl-1  for 5 to 7 s. All treatments were conducted as a completely randomized design with a factorial arrangement. In sexual propagation, each treatment consisted of four replications and in asexual propagation each treatment was replicated six times. Means of two successive years were used for statistical analysis. Means were compared using Duncan's new multiple range test (DNMRT) at 1% level of probability.The results obtained in this research indicated that scarification was necessary for water uptake by seeds, while it was not adequate for germination. Scarification plus stratification or using gibberellic acid resulted in seed germination. The interaction of scarification and stratification and also scarification and gibberellic acid showed that the highest germination percentage 98 and 97% was obtained from 60 min scarification and 45 d stratification or 60 min scarification and using 500 mg mgl-1 gibberellic acid which was significant at 1% level of probability compared to control. The highest hypocotyl fresh weights (1.6 and 2.12 g, respectively) were obtained from 60 min scarification and 45 d stratification or 60 min scarification and using 500 mgl-1 gibberellic acid. The highest germination value (94.383 and 273.24, respectively) resulted from 45 min scarification and 45 d stratification or 60 min scarification and using 500 mgl-1 gibberellic acid.Asexual propagation results showed that hardwood and semi hardwood cuttings were not able to root and only a few percent of softwood cuttings were rooted. These results indicated that auxins under the conditions of this research had a poor ability to induce rooting in this species. However, the highest rooting percentage of softwood cuttings (5 and 3.3 %, respectively) was obtained from 10000 mgl-1 naphthalene acetic acid or 16000 mgl-1 indolebutyric acid.Based on the  data obtained in these experiments, it can be concluded that sexual propagation of this species is recommendable and for optimum germination, seed can be scarified by concentrated sulfuric acid for 45 to 60 min and then being stratified at 3-50°C for 45 d. Alternatively, seeds can be treated with gibberellic acid with concentration of 500 mgl-1 for 24 hr instead of stratification.

In order to obtain seedless fruits from medlar trees, an experiment was conducted with four types of fertilization on 10 trees in 1987 and repeated in 1989. Results indicated that there are significant differences between all four treatments on percentage of fruit set. It has also been proved that allogamy (free pollination) is the most effective method for improving fruits set, and medlar was recognized as a facultative allogamic plant. Parthenocarpy was not observed and all unfertilized flowers were dropped. Apparently, fruit parthenocarpy of medlar trees was due to a stimulative effect during 1984-1986.

To produce early crops, onion transplants were planted in fall and harvested in spring in tropical area of Kemran province. To select suitable cultivar and investigate the possibility of using sets instead of transplants, several field experiments were conducted in two years. In first experiment, 13 exotic short- day cultivars were compared with a local cultivar 'Taxas Earley Grano' for bolting, bulb yield and bulb diameter. Bolting was highly different in cultivars. It was 1%in 'Sawana Sweet', 79% in 'Violet', and 6% in 'Taxas Earley Grano'.Bulb yield was also different in different cultivars. 'Violet' and 'Super Select' produced 4.2 and 60 ton ha-1 , respectively. In 3 other experiments the effects of set size, transplants and concenterations of paclobutrazol in 3 cultivars namely 'Taxas Earley Grano', 'Gold Rash' and 'Super Select' were studied. The response of these cultivars to flowering was different as 'Super Select' was semi -tolerant and 'Gold Rash' was least tolerant.Effects of paclobutrazol on reducing bolting were different in studied cultivars. Paclobutrazol was ineffective in 'Taxas Earley Grano', somewhat effective in 'Gold Rash' and effective in 'Super Select' cultivars. Compared with transplants, sets produced more bulb yield and had less bolting but the trend was different in different cultivars. 'Taxas Earley Grano' sets with 10-15 and 15-20mm diameter had significantly less bolting when compared with transplants. Whereas in 'Gold Rash' and 'Super Select' only sets with 10-15mm size had such a response. It was concluded that small sets can be replaced for transplants.

To evaluate the effects of chemical thinning on fruit weight, size and quality of 'Golden Delicious' apple, an experiment was conducted on the Khalat-Pooshan, Faculty of Agriculture, Tabriz University in 1992. The chemicals used were carbaryl 85% (sevin), 0,300 and 600 mgl-1, 2, 4-D, 0 and 15 mgl-1 and NAA 0 and 15 mgl-1. The chemicals were utilized twice (5 and 25 d after full bloom). Experiment was conducted as a randomized complete block design with a factorial arrangement and four replications. The results indicated that carbaryl and NAA had considerable thinning characteristics an additional effect on apple fruit weight and size, while 2, 4-D sprays showed to be ineffective and even reduced the size and weight of fruits. Application of the chemicals 5 d after full bloom was more suitable. Using 600 mgl-1 carbaryl (5 d after full bloom) had a desirable effect on fruit weight and size (113.8 g and 70.92 mm, respectively). The use of 15 mgl-1 NAA had also additional effect on fruit weight and size (97.22 g and 69.18 mm. respectively). Application of 600 mgl-1 carbaryl (25 d after full bloom) had also beneficial effects on fruit weight and size (104 g and 70.3 mm, respectively) when compared with other treatments. Applying combination of the 600 mgl-1 carbaryl and 15 mgl-1 NAA sharply reduced the fruit number, therefore, increased the fruit weight and size (114.7 g and 72. 69 mm, respectively). The use of different chemical materials showed that they had little or no significant effects on increasing the total soluble solids of the fruits in comparison with control.

A series of experiments were conducted to examine the effects of heat treatments on decay, weight loss and other characteristics of two cultivars of mandarin (Clemantin and Kinnow) during 1998 and 1999 both in cold (6±1° C) and ambient storage. Fruits of both cultivars were treated by warm air (36° C) for 24 and 36 hr and by warm water 25, 40 and 53°C for 2.5 and 5 min.They were dipped in spore suspension of Penicilium digitatum (106 spores l-1). They were kept in cold and ambient storage for 3 and 5 mo after packing in plastic bags. Only warm air for 24 hr reduced percentage of decay significantly during storage. Treatments of warm water before dipping in spore suspension were not effective in controlling of decay during cold and ambient storage.