FOLIAR APPLICATION OF ZINC INFLUENCES THE LEAF MINERAL STATUS,VEGETATIVE AND REPRODUCTIVE GROWTH,YIELD AND FRUIT QUALITY OF ‘KINNOW’ MANDARIN

Deficiency of zinc (Zn) is widespread in many citrus orchards of Pakistan, consequently hampering fruit yield. Effects of foliar applications of zinc sulfate on tree nutrition, growth, productivity and fruit quality were studied on ‘Kinnow’ mandarin. Leaf nitrogen (N), calcium (Ca), and manganese (Mn) were highest for trees sprayed with 0.2% zinc sulfate, while phosphorus (P) and iron (Fe) were highest with 0.6% zinc sulfate and potassium (K) and Zn were highest with 0.8% Zn sulfate applications. Trees sprayed with 0.6% zinc sulfate exhibited highest increase in height, crown width and stem girth, fruit diameter, fruit weight, ascorbic acid contents, and total phenolics compared to all other treatments. Pre-harvest fruit drop was lowest and total number and weight of fruit per tree was highest at harvest with 0.4% zinc sulfate application. In conclusion, foliar application of zinc sulfate up to 0.6% improved tree mineral nutrients, growth, and productivity with better fruit quality in ‘Kinnow’ mandarin.     

FOLIAR APPLICATION OF BORON INFLUENCES THE LEAF MINERAL STATUS,VEGETATIVE AND REPRODUCTIVE GROWTH,YIELD AND FRUIT QUALITY OF ‘KINNOW’ MANDARIN (CITRUS RETICULATA BLANCO.)

The effects of foliar application of boron (B) in the form of boric acid on vegetative and reproductive growth, yield and fruit quality of ‘Kinnow’ mandarin (Citrus reticulate Blanco.) were investigated. Kinnow mandarin was sprayed with different concentrations of boric acid viz. (0.1%, 0.2%, 0.3% and 0.4%) at fruit set stage. Leaf nitrogen (N), phosphorus (P), potassium (K), B, and zinc (Zn) along with flush length, tree height, tree spread and tree trunk diameter increased, while leaf length and leaf age showed non-significant results after foliar B application. Yield of the ‘Kinnow’ mandarin was significantly affected by foliar application of B and a significant increase in fruit weight at harvest was also observed. Soluble solid concentration (SSC): titratable acidity (TA) ratio, ascorbic acid, total sugars, total phenolic content (TPC) and total antioxidants significantly affected, while pH of juice, SSC, TA, reducing sugars and non-reducing sugars showed non- significant results.     

EFFECT OF PREHARVEST SPRAYS OF CALCIUM CHLORIDE AND SUCROSE ON CRACKING AND QUALITY OF ‘BURLAT’ SWEET CHERRY FRUIT

The aim of the study was to examine impact of preharvest sprays of calcium (Ca) and sucrose on splitting and quality of ‘Burlat’ sweet cherry fruit. The study was carried out during 2009–2010 in Poland and Turkey, on mature trees planted at a moderate density on coarse- and medium-textured soils. Sweet cherries were sprayed with calcium chloride (CaCl₂) and/or sucrose at a rate of 5 kg of each material per ha, using ca. 1000 L of water. In Poland, sprays of CaCl₂ and/or sucrose were applied 8–14 h before each rain, starting 21 d before harvest, whereas in Turkey the spray treatments were made schematically: 7, 14 and 21 d before harvest. Sprays of water were treated as the control. The results showed that preharvest sprays of CaCl₂ and/or sucrose did not affect yield, mean fruit weight, and fruit acidity. Sprays of CaCl₂ increased fruit Ca status, and simultaneously reduced fruit cracking in an orchard or laboratory test. In the trial performed in Turkey, part of fruit sprayed with CaCl₂ (<5%) had spray deposit on the peel. Sucrose sprays did not affect fruit cracking. In one year of the study in Turkey, sucrose sprays increased soluble solids concentration of fruit; however, part of fruit treated with sucrose (<2%) had spray deposit on the skin.     

INTERRELATION BETWEEN FRUIT MINERAL CONTENT AND PRE-HARVEST CALCIUM TREATMENTS ON ‘GOLDEN SMOOTHEE’ APPLE QUALITY

The effects of different pre-harvest calcium treatments and their interrelation with other nutrients in apples (Malus domestica Borkh, ‘Golden Smoothee’) on quality attributes at harvest and after cold storage and on relation between calcium (Ca) and other nutrients were investigated. Calcium sprays were applied during three-seasons beginning 60 days after full bloom (DAFB), with 6 or 12 applications in the second part of the growing season. It was confirmed that calcium treatments generally resulted in increased flesh firmness at harvest but not sufficient to maintain during storage. Treatments reduced bitter pit and lenticel blotch pit after cold storage, but these disorders were not totally eliminated. The treatments did not influence evolution of titratable acidity and soluble solids. Total fruit calcium increased with number of applications, but this increase was not proportional with number of applications. The beneficial effect of calcium treatments was reflected in the nitrogen/Calcium (N/Ca), potassium/calcium (K/Ca), and (K+Mg)/Ca ratios.     

EFFECT OF VARIOUS FOLIAR SPRAYS ON SOME FRUIT QUALITY ATTRIBUTES AND LEAF NUTRITIONAL STATUS OF THE PEACH CULTIVAR ‘ANDROSS’

The effect of various products applied as foliar sprays on some fruit quality attributes and leaf nutritional status of the peach cultivar ‘Andross’ for a three year period is reported. Foliar application of all calcium (Ca) products plus boron (B), did not affect mean fruit weight compared to the control. Application of profical plus calcium phosphite plus power 7-B resulted in an increase of flesh firmness. Low flesh firmness was measured at the potassium nitrate (KNO₃) and Chelan-K treatments. Foliar application of all Ca and K products did not alter significantly total soluble solids, total titratable acidity, and length and width of pits in comparison to the control. The highest amount of compact pits (without visual split) for the three year period was measured after foliar application of silene-K. Profical plus calcium phosphite plus power 7-B, and calcium chloride (CaCl₂) plus power 7-B gave also good results for the three years. Foliar application of agriphos, chelan-K, silene-K, and KNO₃ resulted in an increase of K concentration of leaves compared to the control. Foliar application of CaCl₂, bcazin, power-Ca, profical and calcium phosphite plus profical resulted in an increase of Ca concentration of leaves compared to the control for all the years. The efficacy of the foliar sprays varied from year to year indicating the influence of the climatic conditions on tree nutrition.     

EFFECTS OF POTASSIUM NITRATE SPRAYING ON FRUIT CHARACTERISTICS OF ‘MALAS YAZDI’ POMEGRANATE

The present research was carried out to investigate the effects of potassium nitrate on pomegranate fruit quality. Treatments were: 1) control, distilled water was used; 2) potassium nitrate 250 mg L-¹ plus Tween-20 and 3) potassium nitrate 500 mg L-¹ plus Tween-20. All treatments were sprayed on fruits with a diameter of 30 mm. Juice, peel, seed characters, and fruit quality components were evaluated when fruits were harvested. Results indicated that 250 mg L-¹ potassium treatment increased juice volume and weight compared with the control and the 500 mg L-¹ K treatments. As the potassium nitrate level increased, aril length and diameter decreased. Although there was not a significant difference among treatments on titrable acidity and pH contents of fruits, the highest total soluble solids and vitamin C were obtained in the 250 mg L-¹ potassium nitrate treatment when compared with the others. These findings show that applied potassium nitrate significantly influences fruit quality of pomegranate when fruit are in the beginning stages of growth and development.     

EFFECTS OF SINGLE,DUAL AND TRIPLE INOCULATIONS WITH BACILLUS SUBTILIS,BACILLUS MEGATERIUM AND RHIZOBIUM LEGUMINOSARUM BV. PHASEOLI ON NODULATION,NUTRIENT UPTAKE,YIELD AND YIELD PARAMETERS OF COMMON BEAN (PHASEOLUS VULGARIS L. CV. ‘ELKOCA-05’)

This study was conducted in order to investigate the effects of single, dual, and triple inoculations with Rhizobium, N₂-fixing Bacillus subtilis (OSU-142), and P-solubilizing Bacillus megaterium (M-3) on nodulation, plant growth, nutrient uptake and seed yield of common bean (Phaseolus vulgaris L. cv. ‘Elkoca-05’) in comparison to control and mineral fertilizer application under field conditions in 2006 and 2007 in the cold highland in Erzurum plateau (29° 55′ N and 41° 16′ E with an altitude of 1850 m), Turkey. Bacterial inoculations significantly increased all the parameters investigated compared with the control treatment, equal to or higher than nitrogen (N), phosphorus (P), and NP treatments. The lowest shoot dry weight and chlorophyll content values were recorded in the control treatment and the bacterial inoculations increased shoot dry weight by 19.7–54.3% and chlorophyll content by 34.1–59.3% over control. Nodule dry weight significantly increased in Rhizobium alone treatment. Additionally, nodulation by native soil Rhizobium population was increased in single inoculations of OSU-142 and M-3. Significant increases of the seed yield under different inoculation treatments ranged between by 6.6% (Rhizobium + OSU-142 + M-3) and 12.2% (OSU-142 alone) over the control whereas N, P and NP applications corresponded to increases of 5.6%, 4.0% and 7.4%, respectively. All bacterial inoculations, especially triple inoculation, significantly increased uptake of macronutrients and micronutrients by common bean. In conclusion, seed inoculation with Rhizobium, OSU-142 and M-3, especially OSU-142 alone, may substitute partially costly NP fertilizers in common bean production even in cold highland areas such as in Erzurum.     

INFLUENCE OF PREHARVEST SPRAYS OF A MIXTURE OF CALCIUM FORMATE,CALCIUM ACETATE,CALCIUM CHLORIDE AND CALCIUM NITRATE ON QUALITY AND ‘JONAGOLD’ APPLE STORABILITY

The aim of the study was to examine effect of preharvest sprays of a mixture of calcium (Ca) formate, Ca-acetate, Ca-chloride (CaCl₂) and Ca-nitrate [Ca(NO₃)₂] on quality and apple storability. The experiment was conducted during 2008–2009 at the Experimental Station of the Research Institute of Horticulture in Skierniewice, Poland, on mature ‘Jonagold’ apple trees/M.26, planted at a moderate density on a coarse-textured soil with low status of organic matter and abundant in exchangeable Ca. Apple trees were sprayed with Ca, 7 times per season, at 2-week intervals, starting 3 weeks after blooming. In the spray treatments a mixture of Ca-formate, Ca-acetate, CaCl₂ and Ca(NO₃)₂ (as Insol Wap fertilizer), CaCl₂ or Ca(NO₃)₂ were used at rates of 7.3 kg Ca, 11.8 kg Ca, and 9.9 kg Ca ha^?1 per season, respectively. The trees sprayed with water were treated as the control. The results showed that Ca sprays caused no leaf and fruit injury. Calcium spray measures did not affect yield, mean fruit weight, and soluble solids concentration (SSC), titratable acidity and starch index of fruit at harvest. However, at harvest apples sprayed with Ca contained more this nutrient and were firmer than those of the control plots. After storage apples sprayed with Ca had more acids, and were firmer and less liable to bitter pit than the control fruit. Calcium sprays did not affect SSC of fruit after storage but reduced postharvest decay of fruit caused by Peziculla spp. and Penicillium expansum fungi. Apples sprayed with Insol Wap material were the least affected by the above pathogens. It is concluded that in apple orchards preharvest sprays of a mixture of Ca-formate, Ca-acetate, CaCl₂ and Ca(NO₃)₂, containing 10% Ca (w/w) with ca. 50% in an organic form, can be the alternative to sprays of CaCl₂ or Ca(NO₃)₂.     

“JONAGOLD” APPLE FRUIT QUALITY AS INFLUENCED BY FALL SPRAYS WITH CALCIUM CHLORIDE AT HIGH RATES

The aim of the experiment was to examine the effects of fall sprays with calcium (Ca) as calcium chloride at high rates on ‘Jonagold’ apple (Malus domestica Borkh.) fruit quality. Trees were sprayed with Ca both in summer (9, 7, 5, and 3 weeks before fruit harvest) at a rate of 3 kg Ca ha^?1and in fall (one week before fruit harvest) at rates of 8, 16, or 24 kg Ca ha^?1. Fall Ca sprays resulted in leaf injuries and defoliation; however they had no effect on cold hardiness of one-year-old shoots. Fruit yield, weight, maturity at harvest, surface condition, and color were not influenced by Ca sprays during three consecutive years. Fruit Ca concentration corresponded with amount of Ca applied. In two of three years, summer Ca sprays decreased sensitivity of apples to bitter pit. Fruit sprayed with Ca both in summer and in fall had higher firmness and titratable acidity after storage and were more resistant to bitter pit and internal breakdown than controls and fruit sprayed only with Ca in summer. Apples sprayed with Ca in summer and in fall at the highest rate were the least sensitive to bitter pit and internal breakdown and were more resistant to decay than control fruit.     

BIOLOGICAL AND TECHNOLOGICAL STRATEGIES AGAINST SOIL AND WATER SALINIZATION I—RHIZOSPHERE

The work presents an overlook over the main strategies to induce salt stress resistance in horticultural crops that have been developed during the last twenty years, ranging from more traditional agronomical techniques to the more modern ones involving microbiology and molecular biology. These strategies are presented as divided into two main groups: the ones acting on the rhizospheric environment surrounding the plant, presented here, and the ones aiming to provide the plant with actual resistance to salt stress that are the object of a successive work. Consociation with halophytic plants emerges for its promising results and for the lack of a wide number of researches performed, justifying the need to provide deeper insight, particularly with regard to the optimal species, and densities and times of sowing to be used. On the other hand, mycorrhizal infection is a more consolidated practice that is known for its efficacy, but there are still interesting developments to be investigated in the field of its possible interactions with other microorganisms or with additional agronomical treatments such as extra-fertilization. Less decisive solutions are represented by practices like the management of irrigation waters that can be worth the use only in cases of mild stress conditions or in combination with other strategies.     

BIOLOGICAL AND TECHNOLOGICAL STRATEGIES AGAINST SOIL AND WATER SALINIZATION II—PLANT

The work comes to complete an overview, which started with a review about the actions on the rhizosphere, over the main strategies to induce salt stress resistance in horticultural crops that have been developed during the last twenty years. The techniques presented here aim at an induction of resistance to saline stress in the plant organism by operating directly on its metabolism, so that the plant can face higher salt levels in the rhizospheric environment. In particular the use of tolerant genotypes, as can be produced by techniques of molecular biology, is the most studied and is showing an increasing number of new possible applications, but these are subordinated to a deeper understanding of the molecular basis of salt adaptation and salt tolerance. The scarce social acceptance of genetically-engineered crops is another obstacle to their applicability on a large scale. Growth regulators can give a wide range of results depending on the compounds that are used; a new and possibly promising perspective is given by the use of some molecules in plant defenseinduction models. Silicon application is also especially interesting for its effectiveness and for its physiological implication at roots level, and the technique does not present drawbacks connected with an undesired accumulation of the product in the soil in the medium-long term.     

Effect of Fluoride Pollution on pH AND Solubility of Al,Fe, Ca,Mg, K and Organic Matter in Soil from Årdal (Western Norway)

The effect of fluoride (F) on pH and solubility of organic matter (TOC), aluminium (Al), iron (Fe), calcium (Ca), magnesium (Mg) and potassium (K) in soil samples collected near an aluminium smelter in Norway was studied. Increased addition of F to the soil samples led to an increase in pH and concentrations of TOC, Al and Fe in solution. Most of the F and Al in solution were in the forms of ALF_x-complexes. K solubility decreased in some soil samples, but there were no consistent effect on the solubility of Ca or Mg. The effect of NaF addition was significantly different from equimolar NaCl-treatments. The concentrations of Al, Fe, TOC and the pH-values were lower, while the concentrations of K, Mg and Ca were higher in the NaCl-treatments than in the NaF-treatments. The results from the experiment imply that F-pollution of soil induces breakdown of Al- and Fe-oxides/hydroxides and solubilize organic material in the soil. This may influence the availability of potentially toxic elements, such as AIF_x-complexes, to microorganisms and plant roots.     

RESPONSE OF ‘BURLAT’ SWEET CHERRY TREES TO POSTHARVEST SPRAYS OF NITROGEN,BORON AND ZINC

The aim of the study was to examine effects of postharvest sprays of nitrogen (N), boron (B), and zinc (Zn) on reproductive response of sweet cherry (Prunus avium L.) trees, fruit quality and plant nutrition. The experiment was conducted during 2007–2009 in central Poland on mature ‘Burlat’ sweet cherry trees/F12, grown on a coarse-textured soil with low level of organic matter, and optimal soil reaction. Soil status of phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), manganese (Mn), Zn and copper (Cu) was optimal, whereas B – low. Sweet cherry trees were sprayed with boric acid-B, ethylenediaminetetraacetic acid (EDTA)-Zn, and urea-N at 30–40 d prior to initiation of leaf fall according to following schema: i) spray of N at a rate of 23 kg ha^?1; ii) spray of B and Zn at a dose of 1.1 kg ha^?1 and 0.5 kg ha^?1, respectively; and iii) spray of N, B and Zn at the same rates as in the above spray combinations. The trees sprayed with water served as the control. The results showed that fall spray treatments had no influence on cold damage of flower buds, plant N status and soluble solids concentration in fruit. Postharvest spray of N and combined spray of N, B and Zn injured leaves in the fall but did not cause defoliation. Sprays of B and Zn with or without N increased status of Zn and B in fall leaves, and B in flowers and midsummer leaves. Those sprays also improved fruit set and yield. In one out of two years of the study, fall sprays of N with or without B and Zn decreased mean fruit weight. The above results indicate that only leaf-applied B in the fall improved reproductive response of sweet cherry trees. It is concluded that under conditions of B shortage in a soil and/or plant tissues, postharvest B sprays can be recommended in sweet cherry orchards to improve reproductive growth of the trees.     

DO MAIZE AND PEPPER PLANTS DEPEND ON MYCORRHIZAE IN TERMS OF PHOSPHORUS AND ZINC UPTAKE?

Nutrient deficiency, especially zinc (Zn) and phosphorus (P), is a common nutritional problem for the production of some crops in Turkey. This problem results in the application of increasing amounts of several fertilizers. Mycorrhizal inoculation or the indigenous potential of mycorrhizae in the soil is a critical factor in crop production under low supply of Zn and P. The effects of selected mycorrhizal inoculation on growth and Zn and P uptake of maize and green pepper were investigated in Zn- and P-deficient calcareous soils from Central Anatolia. Soils were sterilized by autoclaving and plants were grown for 7 weeks in pots under greenhouse conditions with inoculation of two selected arbuscular mycorrhizal (AM) species (Glommus moseea and G. etunicatum) at three rates of P (0, 25, 125 mg P kg^?1 soil) and two rates of Zn (0 and 5 mg Zn kg^?1soil). Without mycorrhizal inoculation, shoot and root dry matter production were severely affected by P and Zn deficiencies, and supply of adequate amounts of P and Zn significantly enhanced plant growth. When the soil was inoculated with mycorrhizal inoculation, the increasing effects of P and Zn fertilization on plant growth remained less pronounced. In accordance with growth data, mycorrhizae inoculation enhanced P and Zn concentration of plants, especially under low supply of P and Zn. The results obtained indicate that maize and green pepper are highly mycorrizal–dependent (MD) plant species under both low P and Zn supply and mycorrhizae play an essential role in P and Zn nutrition of plants in P and Zn-deficient soils. Although addition of P and Zn increased plant growth and plants are mycorrhizal dependent on P and Zn nutrition however dependence is much more dependent on P nutrition.     

EFFECT OF CITRUS ROOTSTOCKS ON LEAF MINERAL COMPOSITION OF ‘OKITSU’, ‘CLAUSELLINA’, AND ‘SILVERHILL’ MANDARIN CULTIVARS

Citrus performance is strongly related with rootstock. This study was conducted to investigate leaf nutrient contents of ‘Okitsu’, ‘Clausellina’ and ‘Silverhill’ mandarin cultivars budded onto sour orange, ‘Carrizo’ and ‘Troyer’ citrange rootstocks in Dörtyol, Turkey in 2004 and 2005. The maximum nitrogen (N), potassium (K), and copper (Cu) contents were determined for ‘Clausellina’; phosphorus (P) for ‘Okitsu’; and sodium (Na) for ‘Silverhill’. Calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), and zinc (Zn) uptake were similar for the mandarin cultivars. ‘Carrizo’ citrange at N, K, Mg, Mn, and Cu uptake; ‘Troyer’ citrange at N, P, K, and Fe uptake; and common sour orange at Ca, Zn, and Na uptake was superior on the other rootstocks. It was observed that ‘Carrizo’ and ‘Troyer’ citrange rootstocks had advantages over sour orange in nutrient uptake. Thus, growth performance, yield, and quality parameters considered, ‘Carrizo’ and/or ‘Troyer’ citranges could be suggested as rootstocks for the studied mandarin cultivars under similar ecological conditions.