Citrus Decline: Soil Fertility and Plant Nutrition

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<ul><li><p>This article was downloaded by: [Nipissing University]On: 17 October 2014, At: 02:40Publisher: Taylor &amp; FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH,UK</p><p>Journal of Plant NutritionPublication details, including instructions forauthors and subscription information:</p><p>Citrus Decline: Soil Fertilityand Plant NutritionA. K. Srivastava a &amp; Shyam Singh aa National Research Centre for Citrus , Nagpur,Maharashtra, IndiaPublished online: 29 Jan 2009.</p><p>To cite this article: A. K. Srivastava &amp; Shyam Singh (2009) Citrus Decline: SoilFertility and Plant Nutrition, Journal of Plant Nutrition, 32:2, 197-245, DOI:10.1080/01904160802592706</p><p>To link to this article:</p><p>PLEASE SCROLL DOWN FOR ARTICLE</p><p>Taylor &amp; Francis makes every effort to ensure the accuracy of all theinformation (the Content) contained in the publications on our platform.However, Taylor &amp; Francis, our agents, and our licensors make norepresentations or warranties whatsoever as to the accuracy, completeness,or suitability for any purpose of the Content. Any opinions and viewsexpressed in this publication are the opinions and views of the authors, andare not the views of or endorsed by Taylor &amp; Francis. The accuracy of theContent should not be relied upon and should be independently verified withprimary sources of information. 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Terms &amp; Conditions of access and use can be found at</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Nip</p><p>issi</p><p>ng U</p><p>nive</p><p>rsity</p><p>] at</p><p> 02:</p><p>40 1</p><p>7 O</p><p>ctob</p><p>er 2</p><p>014 </p><p></p></li><li><p>Journal of Plant Nutrition, 32: 197245, 2009</p><p>Copyright Taylor &amp; Francis Group, LLC</p><p>ISSN: 0190-4167 print / 1532-4087 online</p><p>DOI: 10.1080/01904160802592706</p><p>Citrus Decline: Soil Fertility and Plant Nutrition</p><p>A. K. Srivastava and Shyam Singh</p><p>National Research Centre for Citrus, Nagpur, Maharashtra, India</p><p>ABSTRACT</p><p>Soil physical properties related constraints (clay gradient in soil profile,drainage/irrigation/waterlogging) and soil fertility constraints induced by soil pH, salin-ity (specific ion-and cumulative osmotic pressure effect), calcareousness (pedogenic ornon-pedogenic CaCO3), besides increasing menace of nutrient mining, are the impor-tant pedological factors contributing to citrus decline. But, the orchards established onlater two soil orders confronted with subsurface constraints in form of argillic (clay richhorizon with acidic or alkaline pH and varying intensity/forms of calcareousness) andspodic horizonation (organic hardpan with very acidic pH), in addition to multiple soilfertility constraints. Soil condition-based rootstock alternatives, site specific nutrientmanagement coupled with variable rate application, and integrated soil managementsystems representing different modules of INM, are the viable means of combating anuntimely decline in citrus orchards productivity.</p><p>Keywords: plant nutrition, nutrient models, horticulture crops</p><p>INTRODUCTION</p><p>Citrus is considered to be one of the most remunerative fruit crops that have alasting niche in international trade and world finance. World citrus productionis dominated by the northern hemisphere, followed by the southern hemisphere,and Mediterranean region contributing 45%, 35%, and 20%, respectively (FAO,2005). There are three basic requirements for successful cultivation of citrus,namely, climate relatively free from frost hazards, good quality of irrigationwater, and reasonably deep and uniform fertile soil with good internal drainage(Nemec, 1986). Citrus decline as popularly known in citrus belts of Indian</p><p>Received 13 August 2007; accepted 21 January 2008.Address correspondence to A. K. Srivastava, National Research Centre for Citrus,</p><p>Amravati Road, Nagpur 440 010, Maharashtra, India. E-mail: aksrivas</p><p>197</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Nip</p><p>issi</p><p>ng U</p><p>nive</p><p>rsity</p><p>] at</p><p> 02:</p><p>40 1</p><p>7 O</p><p>ctob</p><p>er 2</p><p>014 </p></li><li><p>198 A. K. Srivastava and S. Singh</p><p>subcontinent has been the subject of considerable research world over. Cit-rus decline is also known by various other names such as blight in Florida,declinio in Brazil, declinamiento in Argentina, and marchitamiento repentinoin Uruguay, depending upon causal factor. It is referred to as frenching, de-cay, chlorosis, neglectosis, and amachamients in Mexico. The causal factors ofcitrus decline vary in magnitude with the nature of factors (Figure 1).</p><p>Analysis on contribution of climate, soil, and management factors on yieldof Satsuma mandarin demonstrated that yield is more affected by physiographicenvironment than either climate or even fertilizer application (Egashira et al.,1990). A definite correlation exists between elevation and particle size com-position of soils. The average concentration of clay fraction increased from 31to 38% as the elevation increased from 850 to 1500 m above mean sea level(Kong-Tau, 1986). Likewise, many of the soil fertility parameters are reportedto be influenced by variation in altitude (Singh and Dutta, 1983; Avasthe andAvasthe, 1995). These observations assume a greater significance consideringthe fact that citrus culture for commercial purposes is being practiced up to analtitude as high as 2400 m above mean sea level (Ding et al., 1990). But, someof the ornamental species of citrus are grown up to 2800 m in the areas closeto equator (Camacho and Saul, 1981).</p><p>The citrus soils differ from other cultivated soils in many respects. Thecultivated soils remain fallow for 36 months every year, which results indepletion of soil organic matter as very little carbon (C) is added during thefallow phase, while biological oxidation of existing C continues at the samerate as in citrus soils (Sharma and Singh, 2001). Hence, the state of nutrition,size, and yield of citrus are closely related to the amount of soil explored by theroot system (Avilan et al., 1987). Many investigations enumerated the declineof citrus trees to unfavorable surface and subsurface soil conditions (Wutscher,1989; Srivastava and Singh, 2004a).</p><p>Taxonomically, highest quantum of citrus production from citrus is har-nessed from the soils represented by soil orders Entisols, Alfisols, Ultisols, and</p><p>Citrus Decline</p><p>Abiotic Factors Biotic Factors</p><p>Soil-relatedconstraints</p><p>Irrigation Cultural Physiolgical Entomological Pathological* Waterlogging* Water stress</p><p>* Pruning/shading* Excessive bearing* Rootstock-scion incompatibility* Union creasing</p><p>* Hormonal imbalance* Alteration inonand offyear cycle</p><p>* Blackfly* Psylla* Bark eating caterpillar* Leaf miner* Aphids* Mealy bug* Mites </p><p>* Fungal diseases* Bacterial diseases* Viral</p><p>* Salinity* Calcareousness diseases* Nutrient toxicity/ deficiency* Clay gradient* Compaction/ hardpan in subsurface </p><p>Figure 1. Classification of causal factors to citrus decline.</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Nip</p><p>issi</p><p>ng U</p><p>nive</p><p>rsity</p><p>] at</p><p> 02:</p><p>40 1</p><p>7 O</p><p>ctob</p><p>er 2</p><p>014 </p></li><li><p>Citrus Decline: Soil Fertility and Plant Nutrition 199</p><p>Oxisols (Srivastava and Singh, 2003). Comparative studies made on the soilconditions in a young sweet orange orchard with patches of poor growth and inadjacent areas with normal growth revealed that soil conditions in the affectedareas had the presence of higher total soluble salts, higher concentration ofsoluble and exchangeable sodium (Na), and lower soluble calcium (Ca) andmagnesium (Mg) (Milad et al., 1975; Malewar et al., 1983).</p><p>DIAGNOSIS OF CITRUS DECLINE</p><p>Morphological Symptoms</p><p>The problem of citrus decline is often confused with die-back and most of thetime, citrus decline is considered similar to citrus die-back, considering thefact that no sharp distinction exists between them even today. However, for allpractical or operational purposes, the term die-back denotes a lethal conditionleading to rapid death of the plant from top to downward due to one or morepathogenic causal factors, whereas the decline refers to a gradual reduction inorchards productivity which may occur due to nonpathogenic factor (Ghosh,1985).</p><p>The visual symptoms are variable, often nonspecific, and unreliable todetermine the cause- and -effect relationship. Among the factors responsiblefor citrus decline, malnutrition is frequently ascribed to chlorotic condition oftrees. This condition usually develops after initial few years of excellent onyears. Various symptoms comprise of: light green interveinal areas with themidrib, causing yellowish condition of leaf at advanced stages. In this way,growth of the plant is partially retarded, and the plant bears short twigs withnarrow leaves. The shoots have a tendency to die-back and even cause the wholeof the tree to dry completely in the subsequent years. Kiely (1957) describedthe features of morphological symptoms of citrus decline in Sri Lanka as asymptom of a special chlorosis in form of appearance of silvery grey spotson upper surface of leaf in the areas having sandy soils, which resembledvery much the symptoms of marble chlorosis induced by manganese (Mn)-deficiency. These symptoms also resemble to those of zinc (Zn)and iron(Fe)deficiencies in Kinnow mandarin orchards of northwest India (Randhawaet al., 1967). Of late, multi-micronutrient deficiency in Marathwada region ofMaharashtra, India was established to be the causal factor for sweet orangedecline (Srivastava and Singh, 2004a).</p><p>The declinio in Brazil showed the similar symptoms and characteristics asblight in Florida (Syvertsen et al., 1980). The leaves of affected trees indicateZn-deficiency like symptoms, wilt in the canopy, followed by leaf fall, twigdie-back, abnormal flowering, and general canopy decline Visual symptoms arealso adapted for a rational canopy rating: zinc deficiency symptoms in leaves,wilting of part or all canopy, leaf drop, twig die-back, abnormal lowering,</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Nip</p><p>issi</p><p>ng U</p><p>nive</p><p>rsity</p><p>] at</p><p> 02:</p><p>40 1</p><p>7 O</p><p>ctob</p><p>er 2</p><p>014 </p></li><li><p>200 A. K. Srivastava and S. Singh</p><p>general canopy decline, internal growth of new shoots, or reduced size of fruit(Rossetti et al., 1990). Canopy rating by these visual symptoms is recommendedon the scale of 0.03.0 (0.0 healthy, 0.01.0 initial declinio stage, 1.02.0intermediate stage, and &gt; 3.0 advanced stage).</p><p>Diagnostic Criteria</p><p>Important criteria to distinguish decline-affected trees from healthy trees are:reduced water uptake in the trunk by water injection, presence of amorphousplugs in xylem vessels, rate of canopy decline by visual tree vigor, high zincaccumulation in the trunk wood and phloem, and low or no water flow throughsecondary roots of affected trees (Lee et al., 1984; Brlansky et al., 1986; Rossettiet al., 1990). These criteria are the same as those applied to distinguish blightedtrees in Florida. Soil fertility does not appear to be a direct causal factorin blight incidence, though a considerable redistribution of nutrient elementstakes place within the trees as a secondary transformation. This diagnostic test,along with trunk water uptake, is widely used to identify citrus blight in thecountries like South Africa, Uruguay, and Argentina (Wutscher et al., 1982a;1982b). Young et al. (1980) showed that trunk wood Zn accumulation occurredin outer wood, whereas reduced water movement took place in inner wood.Wutscher and Hardesty (1981) proposed cation-anion ratio and water solublenutrients in soil as promising approaches to explain the citrus blight syndrome.According to many studies, an elevation in wood Zn concentration took placeprior to visual symptoms in 58% of the trees developing blight, and in restof the 42% of these trees accumulation occurred 3 years before the develop-ment of such visual symptoms (Wutscher et al., 1977; Wutscher and Hardesty,1981).</p><p>SOIL PHYSICAL PROPERTIES RELATED CONSTRAINTS</p><p>Most of the soil-plant-water relations are governed by physical properties ofsurface and sub-surface soil. Influence of soil physical properties on tree growthof mid-season cultivars (20-year-old sour lemon and 25-year-old Valencia onsweet lemon rootstock indicated a much better tree growth under grass on thesoil type having clay content 10% at 3070 cm than on the soil type under cleancultivation (Nel, 1980).</p><p>Particle Size</p><p>Particle size distribution in governs soil-water-plant relation. Review of texturalvariation in Ap horizon of citrus growing soils across the commercial citrus belts</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Nip</p><p>issi</p><p>ng U</p><p>nive</p><p>rsity</p><p>] at</p><p> 02:</p><p>40 1</p><p>7 O</p><p>ctob</p><p>er 2</p><p>014 </p></li><li><p>Citrus Decline: Soil Fertility and Plant Nutrition 201</p><p>showed that the soils predominantly high in sand with comparatively heaviersubsurface are best suited for top citrus production. These soils preferably be-long to soil orders viz., Entisols, Inceptisols, Alfisols, and Spodosols (Florida,USA) with a small proportion of Ultisols (India, Brazil, SriLanka, China, andJapan), Aridisols (Argid in California and Arizona of the USA, Mexico, SouthAustralia, and South-west Africa), and Vertisols (central India, Greece, Mexico,and Venezuela) having large variation in pH and CaCO3 (Table 1). Compar-ison of physical characteristic of soils belonging to Floridana (Entisols) andHolopaw (Alfisols) families under healthy versus blight affected Hamlin treesshowed a comparatively higher proportion of fine textured particles in the rootzone of latter soil type associated with lower hydraulic conductivity and avail-able water (Shih et al., 1986). Decline of sweet orange trees (marchitamientorepentino) on trifoliate orange (Poncirus trifoliata) occurred only in patchesof heavy clay soil in the area of Concordia, Enter Rios province of Argentina(Swartz et al., 1980), since the amount of clay in soil correlated negatively withfeeder roots in all the soil layers (Koudounas, 1994).</p><p>In central India, in the absence of low temperature (cumulative 810 hoursof 510C for 1214 days during December-January for spring flush) sufficientto induce flowering, soil water deficit stress is usually adopted by withholdingirrigation (duration of which varies as per soil depth and texture) which resultsinto concerted flowering following the resumption of irrigation. The successto induction of flowering is, therefore, largely dependent upon the physico-chemical properties of both surface as well as sub-surface soil (Table 2), whichin turn influenced the orchard ef...</p></li></ul>