The Valencia orange is a high quality fruit grown in Turkey; however, small fruit size resulting in poor packouts is common in Valencia oranges. Small fruit size is the main factor limiting the marketing of Valencia oranges; thus, synthetic auxins are commonly used to enhance the size of citrus fruit. The objective of the present study was to observe the effects of 3,5,6-trichloro-2-pyridyloxyacetic acid (3,5,6-TPA) on fruit size, yield and quality of Valencia oranges from 29-year-old trees budded on sour orange rootstock in Adana, Turkey in 2006. The application of 3,5,6-TPA to the entire tree was from 8th to 11th week after anthesis during June drop (JD). Following 3,5,6-TPA treatments, different combinations were used in the experiment: T1 2 tablets per 100 litres applied just after the end of June drop (JD), T2 2 tablets per 100 litres applied 5-7 days after the end of JD, T3 3 tablets per 100 litres applied 5-7 days after the end of JD, T4 4 tablets per 100 litres applied 5-7 days after the end of JD, T5 3 tablets per 100 litres applied 10-14 days after the end of JD and control trees receiving no 3,5,6-TPA (T0).
Based on experience in West China, physiological responses to pruning of orange trees are quite different from apples. While winter pruning in suitable but not excessive amounts stimulates the vegetative processes of apples, it enhances the reproductive processes of citrus and summer pruning does the opposite. As a supplementary practice to winter pruning, summer pruning of oranges at the right time with specific techniques will invigorate neglected and old trees and modify the alter nate bearing habit of healthy trees. During the on-year, trees respond to moderate summer pruning by producing moderate amounts of summer flushes which increases the shedding of young fruits. Thus, the on-year crop will be reduced and the next year crop increased. This is “physiological thinning/’ as compared to chemical or hand thinning. Excessive summer pruning before the time of “June drop” can result in considerable fruit drop.
Citrus production is declining worldwide due to several biotic and abiotic factors. The diseases caused by Phytophthora spp. present major economic risks since they are soil-borne and spread quickly if environmental conditions are favorable, or irrigation is poorly managed. Phytophthora species are present in all citrus-producing areas around the world causing significant losses in crop yield and affecting tree health. Bark infection, damping-off, root rot, gummosis, brown rot, and cortical root rot are among the typical symptoms caused by Phytophthora spp. The pathogenicity of Phytophthora spp. depends mainly on the specific interactions between the isolates and citrus cultivars.
Girdling effects on fruitlet abscission, leaf chlorophyll, chlorophyll a fluorescence and carbohydrate concentration in various flowering and vegetative shoots were studied during natural fruit drop in two Citrus cultivars. Irrespective of shoot type, girdling delayed fruitlet abscission, but only fruitlets borne on leafy shoots had increased final fruit set. Chlorophyll a fluorescence analysis revealed differences in quantum yield efficiency of photosystem II of light adapted leaves (ΦPSII) among shoot types and in response to girdling. In young leaves of vegetative shoots, girdling decreased ΦPSII, whereas ΦPSII increased from Day 30 after girdling in young leaves of leafy flowering shoots; however,ΦPSII did not change in mature leaves during fruit set in either control or girdled trees.
Originating in Japan, Satsumas are an easy-peeling mandarin citrus that is known for its cold-hardiness.
Satsumas are the first mandarins to ripen in Southern Africa, providing an early foot in the door to markets. However, they do come with significant challenges. Citrus Research International (CRI) conducts cultivar trials to evaluate cultivar suitability to various climatic regions. Cultivar ripening windows, production and fruit quality are evaluated over a number of seasons, often spanning eight years. A cultivar trial was established in Citrusdal to evaluate the climatic suitability of this region for Satsuma production. Cultivars Aoshima, Belabela, Imamura, Miho Wase, Miyagawa Wase, Sugiyama and Ueno were imported to SA over time and introduced to the Citrus Improvement Scheme (CIS). These are open cultivars, apart from Belabela which is managed by cultivar agent Citrus Genesis.
Reviewing the Commercial Potential of Hand Thinning in Citrus with a Cost-benefit Analysis of Summer Hand Thinning of ‘Nadorcott’ Mandarin
Hand thinning is not often applied as a commercial cultural practice in citriculture due to the practice’s reliance on costly manual labor. However, hand thinning could provide unique benefits such as treatment selectivity and easier control over thinning intensity, as opposed to foliar sprays of chemical thinning agents. In ‘‘on-year’’ ‘Nadorcott’ mandarin (Citrus reticulata) trees, summer (January) and autumn (April) hand-thinning treatments of removal of all fruit <20 and <40 mm diameter were evaluated for effects on leaf carbohydrates and fruit growth rate. Other factors assessed included treatments’ effects on tree total fruit yield, fruit quality, and fruit size distribution. In addition, two different summer hand-thinning treatments (removal of all fruit <20 and <25 mm) were evaluated for effects on fruit size distribution and fruit yield over two seasons to determine their potential financial implications.
Girdling branches increased flowering in citrus. The number of buds sprouted increased following treatment but the response markedly depends on the time of girdling, summer being most effective. All types of shoots, except vegetative ones, are increased in number but with no differences in its characteristics.
Effect of elemental sulphur and compost on pH, electrical conductivity and phosphorus availability of one clay soil
Suitable plant nutrition is one of the most important factors in the quantity and quality of crops’ yield. In plant nutrition, each nutrient should be in adequate level. The most important role of pH is the control of nutrients solubility in soil. Nutrient availability usually decreases with increasing pH. Experimental soil sample was collected from 0 to 30 cm depth from Niar village around the Ardabil city.The soil samples were mixed with solid acidifying material including elemental sulphur (S) in three levels (0.25, 0.5 and 1.0 g/kg soil), farm yard compost manure in three levels (2.5, 5 and 10 g/kg soil) and elemental S + organic matter in three levels (the same amounts of S with 5 g/kg cattle manure), and filled in 4 L pots. Soil water content was held close to field capacity and green house temperature was kept to 25 ± 5°C. Before the experiment, the physicochemical properties of soil and chemical properties of the compost were measured. At eight, 16 and 32 weeks of incubation, compound soil samples were collected from pots, and their pH, electrical conductivity (EC) and phosphorus (P) were measured.