Volume 25 (2017): Issue 1 (June 2017)

Roses are the most important crop in the floriculture industry and attract both pollinators and human admirers. Until now, a lot of research focusing on postharvest physiology including flower senescence has been conducted, leading to improvement in vase life. However, few studies have focused on the physiology of petal growth, the perception of light by petals, and the relationship between petal growth and environmental conditions. Regarding roses, whose ornamental value lies in the process of blooming from buds, it is also important to understand their flowering mechanisms and establish methods to control such mechanisms, as well as focus on slowing the aging process, in order to achieve high quality of postharvest cut roses. Elucidation of the mechanisms of rose flower opening would contribute to enhanced quality and commercial production of floricultural crops as well as greatly advance basic scientific knowledge regarding plant biology. In this review, we describe the progress and future prospects in the study of petal growth physiology of cut roses.

To evaluate the seven species of Tanacetum genus - Tanacetum balsamita, T. parthenium, T. pinnatum, T. polycephalum, T. tabrisianum, T. uniflorum, and T. vulgare - an experiment was conducted in Karaj Iran. Data were recorded for plant canopy cover, plant height, flower number per plant, aerial biomass yield, time required for flowering, growing degree days to flowering (GDD), essential oil percentage and yield. Results showed that T. parthenium had higher mean values for plant canopy cover, plant height and flower number per plant whereas the species of T. parthenium, T. balsamita and T. vulgare had higher aerial biomass yield in comparison to the other species. The T. balsamita coupled with aerial biomass yield had the highest essential oil concentration. The T. tabrisianum and T. uniflorum were earliest ripening species due to lowest GDD. Essential oil yield was positively and significantly correlated with the traits that are components of aerial mass, indicating that selection for breeding new cultivars should focus on increased aerial biomass yield, late flowering and high flower number.

Transverse sections (2 mm thickness) of stem-nodes from in vitro raised seedlings had morphogenic potential on semisolid and liquid Murashige and Skoog medium supplemented with cytokinins N⁶-benzyladenine (BA 4.44 μM), furfurylaminopurine (KIN 4.65 μM) and auxin α-naphthalene acetic acid (NAA 5.37 μM) individually and in combinations. The regeneration response was influenced by both the type of growth regulator and physical state of the medium. The explants produced either shoot buds on cytokinincontaining media or protocorm-like bodies (PLBs) on NAA containing media both solid and liquid. More neo-formations were produced on liquid media, especially those containing only NAA. They were formed at nodal and inter-nodal regions. The secondary buds were produced on the surface of primary PLBs. The plantlets were developed on MS medium containing banana homogenate 50 g·dm^-3. The current study is the first ever report on successful regeneration of Dendrobium chrysotoxum from stem-node segments.

Silicon supplementation may lead to positive changes in plant quality, including their appearance. The two-factorial experiment with three ornamental plant taxa Gazania rigens ‘Kiss Yellow’, Salvia farinacea ‘Fairy Queen’ and Verbena ‘Obsession Lilac’ was conducted in the years 2012-2013. The first factor was foliar application of Si in form of ortho-silicic acid stabilized with choline (YaraVita Actisil) at the concentrations of 60, 120 and 180 mg·dm^-3, while the second was soil application of multinutrient fertilizer (Insol U) at the concentrations of 0.25% and 0.50%. Biometric measurements of plants were carried out at the beginning of flowering. The laboratory analyses included the determination of the content of P, K, Ca, Mg and Si as well as chlorophyll content in the leaves. Silicon had a beneficial influence on a majority of the analysed morphological features. Plants reacted best to high silicon doses (120 and 180 mg·dm^-3). Particularly beneficial effects were noted with respect to improved flowering of all analysed plant taxa and to the vegetative development of Salvia and Gazania. Insol U supplementation noticeably improved the flowering of Verbena.

Growth retardants have great potential to balance between vegetative and reproductive growth. To assess the effects of prohexadione-calcium (Pro-Ca, Regalis) on reproductive and vegetative growth, return bloom, fruit set, and also fruit quality in ‘Golden Delicious’ apple grafted on M.9 rootstock, an experiment was performed during 2010-2012. The applications of 125 mg dm^-3 Pro-Ca on the same trees in each year resulted in a 40-43% shoot length reducing. Internodes length decreased with Pro-Ca at about 30%, while total node number was unaffected. Results indicate that Pro-Ca applications have no effects on tree trunk growth, flowering, yield, fruit set and development. Pro-Ca also didn’t have any negative impact on fruit quality during the three consecutive years. Moreover, Pro-Ca resulted in higher fruit size compared to control in the third year of trial. The results of this experiment clearly suggest that fruit growers can use Pro- Ca for the control of vegetative growth without having any negative effects on fruit quality and yield parameters. Once a full canopy has been achieved, annual shoot growth can be suppressed in the range of 20 to 30 cm with 125 mg dm^-3 Pro-Ca treatment in ‘Golden Delicious’ apple trees.

The growth of fruits was evaluated during three growing seasons on four apple cultivars ‘Angold’, ‘Jonagold’, ‘Rubinola’ and ‘Topaz’. The follow-up period was defined by the start of flowering, the date of attaining of T-stage by fruitlets and the start of optimal harvest ripening, which for each cultivar was determined on the basis of starch index, flesh firmness and soluble solids. The close relationships were detected between time of attaining the T-stage and term of harvest maturity for three of four studied cultivars.

The aim of the study was to determine the possibility of harvesting raspberries with a pulsating air stream that causes the shoots of plants to vibrate. Two tractor-driven test devices were developed under this specific objective. The first one was a high capacity compressor, and the stream of air produced by it was directed onto one side of a row of plants. The second one was a device producing two counter-flowing air streams colliding in the middle of a row of plants. The frequency of the air pulses was adjusted steplessly by varying the rotational velocity of the shutters closing and opening the outlets of the fans. In the field trials with the device based on a compressor-generated air stream, two air pulse frequencies were used: 500 and 540 pulses per minute (8.3 and 9 Hz). The mean detachment force was 0.727 N. About 50% of ripe raspberries were removed from the bushes. The results achieved during harvesting with the device operating on the principle of colliding two pulsating air streams were markedly better and put the harvesting effectiveness within the range achieved in the trials with combine harvesters with mechanical finger shakers conducted by other researchers. For two pulse frequencies (8 and 9 Hz), almost 62% of fruits were harvested. Increasing the pulse frequency of the counter-flowing air streams above 9 Hz did not improve the effectiveness of detaching raspberry fruits from shoots.

The investigation was conducted to determine the best harvesting time and the storage period of some quince cultivars and promising genotypes from the collection of quince germplasm in the Horticultural Research Station of Isfahan, Iran. For this study, fruits of ‘Vidoja’ and ‘Isfahan’ cultivars as well as promising genotypes PH2 and NB4 were harvested on 6, 14 and 21 October 2015 and 2016 and then stored at 0 ± 1 °C with 90 ± 5% R.H. for five months. Weight loss, firmness, total soluble solids (TSS), titrable acids (TA), taste index, pectin, total phenols, and percent of decay and surface browning of fruits were measured immediately after harvest and one-month intervals after storage in a factorial experiment based on a completely randomized design with three replications and 10 fruits per each replication. The results showed that ‘Isfahan’ cultivar had the highest TSS (18.83%), total phenols and weight loss. The least weight loss was observed in the ‘Vidoja’ cultivar. NB4 genotype showed the least taste index and pectin, while the most pectin and firmness was related to PH2 genotype. Generally, the delay in harvesting and prolongation of storage led to increasing of TSS and weight loss and declining of firmness and phenols, TA, and pectins. Until the third month of storage, there was no surface browning. Browning symptoms were observed from the fourth month of storage and increased in the fifth month up to 1.72%. Generally, the best harvesting time for ‘Vidoja’ was 185 days and for the rest of the genotypes, it was 193 days after full bloom. Fruit storage for four months in cold is advisable for these cultivars and genotypes.

A field experiment was conducted in the forest-savanna transition zone of Nigeria from May to July 2014 and September to November 2015 to determine the impacts of poultry manure (PM) and NPK fertilizer on soil physical properties, and growth and yield of carrot (Daucus carota L.). The five treatments included no manure or fertilizer (control); 10, 20, and 30 megagrams (Mg)·ha^-1 of PM; and 300 kg·ha^-1 of 15 N-15 P-15 K fertilizer. All levels of PM reduced soil bulk density and temperature, and improved total porosity and moisture content compared to the NPK fertilizer and the control. Plant height, number of leaves, root diameter, root length, and fresh root yield in the PM and NPK fertilizer treatments were improved compared to the control. Growth and yield parameters of carrot plants treated with 20 and 30 Mg·ha^-1 PM were higher than the other treatments. The 10 Mg·ha^-1 PM and NPK fertilizer treatments produced similar growth and yield responses. There was an interaction for year (Y) × fertilizer (F) on plant height, number of leaves, and fresh root yield. Relative to the control 10, 20, or 30 Mg·ha^-1 PM and NPK fertilizer increased fresh root yield of carrot by 39.9%, 62.0%, 64.9%, and 37.3%, respectively. The 20 Mg·ha^-1 PM treatment best improved soil properties and carrot productivity as indicated by the benefit-to-cost ratio.

This study aims to improve our understanding of silicon’s role in deterring herbivores from Cucumis sativa. We hypothesized that silicon’s role in plant defense is due to the presence of silica augmenting other physical and/or chemical defenses used by the plant. Using C. sativa plants treated with either a silica fertilizer treatment (Si+) or a control solution (Si-), we monitored feeding preferences of two types of herbivores, a chewing herbivore (Diabrotica balteata) and a piercing/sucking herbivore (Bemisia tabaci). Leaves from treatment plants were visited less and eaten less than leaves from control plants. We then assessed the differences in physical defenses by comparing the leaf structural components, nutrient and water content, and trichome density between treatment and control plants. For chemical plant defenses, we measured leaf carbon and nitrogen levels in, and volatile organic compounds (VOCs) from treatment and control plants. We found no significant difference between treatment and control plants in: lignin content, most elemental plant nutrients, water content, trichome density, and quantity of carbon and nitrogen. We did see an increase in the VOC Indole, known for plant defense priming, an increase in phosphorous levels and a decrease in cellulose levels in silica treated plants.

Two Allium species (A. akaka S.G. Gmelin and A. elburzense W.) native to Iran are used locally as the fresh vegetables and in medical therapy. They are not cultivated, but are collected from the wild, thus, will soon be threatened with extinction. In this study, the diversity of 15 wild accessions (4 accessions of A. elburzense endemic of Iran and 11 accessions of A. akaka) collected from the north-western part of Iran were evaluated with the use of 16 qualitative and 16 quantitative characteristics. The morphological characters with high heritability included leaf length, flower number in umbel, inflorescence diameter, leaf dry weight, bulb fresh weight, weight of 100 seeds, seed length and seed length/width. Results of the principal component analysis indicated that 92.52% of the observed variability was explained by the first six components. The first two components explained about 64.74% of the total observed variability. The first and third hierarchical cluster analysis included all accessions of A. akaka. The accessions of A. elburzense, except one, were placed in a separate cluster. These morphological descriptors can successfully apply for evaluating morphological diversity of Allium wild accessions and can help in horticultural usage.

Cucumber (Cucumis sativus L.) is widely cultivated in many parts of the world. Its production is significantly affected by Fusarium root and stem rot, which is caused by the fungus Fusarium oxysporum f. sp. radicis-cucumerinum, a major disease of cucumber in some regions. Most of the management programs for the control of Fusarium root and stem rot are not successful; therefore, growing resistant cultivars may be the best solution. Use of disease-resistant cultivars is a key to environmentally friendly and economically sustainable disease control in modern crop production. To find resistance sources, 10 F₁ cucumber hybrids were screened against F. oxysporum f. sp. radicis-cucumerinum. Total phenolic content (PC), soluble peroxidase (POX), and polyphenol oxidase (PPO) activities were evaluated at 0, 4, and 8 days after inoculation. Significant differences were observed between resistant and susceptible genotypes in increase of total PCs and enzymatic activities at fourth day after inoculation. These findings can be used in breeding programs of cucumber aiming at creating F₁ cultivars resistant to Fusarium root and stem rot.

This study examined 36 accessions of melon grown originally in dry and warm zones managed in the gene bank in the Institute of Seed and Plant Improvement, Karaj. To characterize and compare results of the field experiment statistical procedures, hierarchical cluster analysis, principal component analysis (PCA), and multiple linear regressions were applied. The results indicated a high degree of variability for single plant yield, fruit weight, fruit length, and cavity diameter. In addition, the variables of fruit size displayed a high differentiating power. Positive and negative correlation coefficients were identified among the studied traits as well. The highest significant positive correlation was found between the plant yield and fruit weight (0.88). Also, the highest significant negative correlation was observed between relative water content and canopy temperature (−0.58). Melon accessions were classified into three main clusters, indicating that the characterized melon collection has a high potential for particular breeding goals. The usefulness of the identified correlations among traits is valuable for the potential use in breeding projects directed for fruit size and yielding in dry condition. Multiple linear regressions were done and R² (Coefficient of determination) and RMSE (Root Mean Squared Error) were 0.97 and 229, respectively.