31 Jul 2019
Citrus Improvement

Quality and Quantity Improvement of Citrus: Role of Plant Growth Regulators

Harsimrat K. Bons, H.S. Rattanpal
Department of Fruit Science, Punjab Agricultural University, Ludhiana, Punjab, India.
Nirmaljit Kaur
Department of Botany, Punjab Agricultural University, Ludhiana, India.

Citrus is one of the most important fruit tree species in the world, as the fruits are a valuable source of nutrients, vitamins and other antioxidant compounds. The citrus productivity depends on various factors, among these the plant growth regulators holds a prime position. The use of plant growth regulators has become an important component in the field of citriculture because of the wide range of potential roles they play in increasing the productivity of crop per unit area. The plant growth regulating compounds actively regulate the growth and development by regulation of the endogenous processes and there exogenous applications have been exploited for modifying the growth response.

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26 Jun 2019
Pink Apple

The effects of organic and inorganic mulches on the yield and fruit quality of ‘Cripps’ Pink’ apple trees

Van der Merwe, Johannes Dawid Prins 
Thesis (MScAgric)–Stellenbosch University, 2012.
http://hdl.handle.net/10019.1/71950

Limited research is available on the effect of mulches on established orchards. Most of the information available stems from research conducted in newly planted orchards or on annual crops such as green peppers and strawberries under greenhouse conditions. To increase the current knowledge on the effect of mulches in established orchards, two field trials were conducted on 14 year old „Cripps‟ Pink‟ orchards. The one trial concentrated on the influence of mulches on the root environment and the other trial on the effect of mulches on growth, yield and fruit quality.

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26 Jun 2019
Soil Surface

Effects of soil surface management practices on soil and tree parameters in a ‘Cripps Pink’/M7 apple orchard 2. Tree performance and root distribution

John Wooldridge, Johan Fourie & Marlise E Joubert
https://www.tandfonline.com

There are around 22 000 ha of commercial apple orchards in South Africa. Of these, 70% are located in the upland areas of the Western Cape. The apple industry exports c. 40% of its production and supports an on-farm labour force of 27 800 (Hortgro 2012. Apple producers are currently adjusting their production techniques to meet increasing consumer demands for organic over conventionally produced fruit.

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22 Jun 2019
Asian citrus psyllid

Being Vigilant: HLB and South Africa

Hein Gerber and Christine Spreeth
First Fruits Consulting

Citrus greening disease takes two forms: Huanglongbing (HLB), the devastating Asiatic strain of citrus greening disease caused by the bacterium Candidatus leberibacter asiaticus and African greening disease, caused by the bacterium Candidatus lebiribacter africanus. Both forms can be spread by infected plant material or by citrus psyllid vectors, namely Diaphorina citri (Asiatic greening) and Trioza erytreae (African greening) (Gottwald et al., 2007). When a vector is carrying the bacteria, it is called a ‘hot vector’ (Jansen, 2019). The psyllid vectors transfer the disease-causing pathogens when they feed on plant sap from citrus leaves (Grafton-Cardwell et al., 2006).

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21 May 2019
Biostimulant activity

Biostimulant activity of phosphite in horticulture

Fernando C. Gómez-Merinoa
Colegio de Postgraduados Campus Córdoba, Veracruz
Libia I. Trejo-Téllezb
Colegio de Postgraduados Campus Montecillo, Mexico

Phosphite (Phi), a reduced form of phosphate (Pi), is emerging as a novel biostimulator in horticulture. Though there is still no consensus on its physiological function as a P-source for plant nutrition, experimental evidence has shown that Phi can act as a biocide and affect plant production and productivity. Positive effects of Phi on plant metabolism are more evident when applied to the roots in hydroponic systems or to the leaves in the form of foliar sprays in the presence of sufficient Pi. Published research conclusively indicates that Phi functions as an effective pesticide against various species of pathogenic bacteria and Oomycetes. Nonetheless, the use of Phi as a sole P-source for plant nutrition is still at issue.

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30 Apr 2019
Aluminum toxicity

Aluminum Toxicity and Tolerance in Plants

Emmanuel Delhaize and Peter R. Ryan
Division of Plant Industry, Commonwealth Scientific and Industrial Research Organization, Australia

The most easily recognized symptom of Al toxicity is the inhibition of root growth, and this has become a widely accepted measure of A1 stress in plants. In simple nutrient solutions micromolar concentrations of Al can begin to inhibit root growth within 60 min. However, the inhibition of growth per se offers little information about the causes of stress that will either precede or coincide with changes in growth. To understand the mechanisms of Al toxicity, it is essential to identify the primary sites involved, both anatomical and metabolic, being mindful that A1 could have diverse effects and act differently in different species.

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30 Apr 2019
Aluminum toxicity

How do Citrus Crops Cope with Aluminum Toxicity

KKIU Arunakumara
Department of Crop Science, Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya, Sri Lanka
Buddhi Charana Walpola1,  Min-Ho Yoon
Department of Bio-Environmental Chemistry, College of Agriculture and Life Sciences, Chungnam National University, Daejeon, 305-764, Korea

World Agriculture faces daunting challenges in feeding the growing population today. Reduction in arable land extent due to numerous reasons threatens achievement of food and nutritional security. Under this back ground, agricultural use of acidic soils, which account for approximately 40 % of the world arable lands is of utmost important. However, due to aluminum (Al) toxicity and low available phosphorous (P) content, crop production in cidic soils is restricted. Citrus, in this context, gains worldwide recognition as a crop adapted to harsh environments. The present paper reviewed Al toxicity and possible toxicity alleviation tactics in citrus.

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30 Apr 2019
Aluminium in Acid Soils

Aluminium in Acid Soils

Dragana Krstic, Dragoslav Nikezic
University of Kragujevac, Faculty of Science
Ivica Djalovic
Institute of Field and Vegetable Crops
Dragana Bjelic
University of Kragujevac, Faculty of Agronomy
Serbia

Soil acidity is a limiting factor affecting the growth and yield of many crops all over the world. The basic problems concerning chemical properties of more acid soils are, besides acidity itself, the presence of toxic compounds and elements, such as soluble forms of Al, Fe and Mn, nitrites and various toxic organic acids. Aluminium (Al) toxicity is one of the major constraints on crop productivity on acid soils, which occur on up to 40% of the arable lands of the world.

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