PHYSIOLOGICAL DISORDERS IN COTTON

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Physiological disorders in cotton,1 Introduction,2 Physiological Disorders. 2 1 Leaf Reddening,2 2 Parawilt New Wilt,2 3 Leaf Drying Burn. 2 4 Bud and Boll Drying,2 5 Bad Boll Opening,2 6 Crazy Top. 2 7 Crinkle Leaf,2 8 Effect of 2 4 D,2 9 Bud and Boll Shedding. 3 Mineral Nutrition Deficiency Toxicity,4 Future Line of Work.
Technical Bulletin from CICR www cicr org in 2,Physiological disorders in cotton. PHYSIOLOGICAL DISORDERS IN COTTON, Cotton known as the King of fibres occupies a unique position in Indian Agriculture. Its cultivation dates back to centuries Presently this crop is grown under varying agro climatic. conditions It is noticed with distress that innumerable abiotic and biotic factors affect cotton. thus limiting productivity Physiological disorders appear as a consequence of nutritional. hormonal imbalances and vagaries in environmental conditions A proper understanding of these. disorders will be useful while taking up appropriate control measures. Studies on physiology and biochemistry of abiotic disorders in terms of processes and. metabolism nutritional deficiency toxicity and their symptoms will provide plethora of scientific. information for further refinement of management strategies Further implementation of WTO. accord pertaining to trade and economy will lead to stiff global competition and we have to. guard ourselves from such onslaughts on our economy As cotton researchers our prime. objective should be to develop appropriate technologies and provide an impetus for enhanced. production and quality through scientific research and technology adaptation in cotton. cultivation, The technical bulletin Physiological disorders in Cotton contains comprehensive and. useful information on various disorders with suitable illustrations and management options I am. confident that this bulletin will be of immense use to all those concerned directly or indirectly. with cotton research development and cultivation,PHUNDAN SINGH. Technical Bulletin from CICR www cicr org in 3,Physiological disorders in cotton.
List of Figures, 1 Photosynthetic leaf area affected by a abiotic and. b biotic stress factors,2a Leaf reddening in the plant canopy. 2b Intensity of reddening as compared to normal leaf. 3 Field view of parawilt affected cotton plants, 4 Parawilt affected plants with a large canopy and. b heavy boll load, 5 Flow chart showing the possible involvement of various processes in causing. 6 Leaf drying in arboreum,7a Bud and boll drying in hirsutum.
7b Bud drying in arboreum, 8 Improper boll opening a bad boll and b normal boll. 9 Crinkle leaf symptom in the top canopy, 10 Malformation of leaf and floral parts due to 2 4 D effect. 11 Apical meristematic region of a normal and b 2 4 D affected plant. 12 Square at initial stage of its abscission, 13 Typical inter veinal chlorosis symptom of cotton leaf. Technical Bulletin from CICR www cicr org in 4,Physiological disorders in cotton. 1 INTRODUCTION, Cotton is an important cash crop grown in India It occupies an area of about 8 5 million.
hectares and is grown in both irrigated and rainfed tracts More than 70 per cent of the total. cropped area is under rainfed condition and the lint yield per hectare 375 Kg is low as. compared to the world average 650 kg Under rainfed condition cotton production mainly. depends on the timing and amount of rain which is unique in every year The duration of cotton. crop is quite long owing to its indeterminate growth habit Therefore both genotype and. environment have conspicuous effects on growth and development. In cotton the growth profile has initial lag phase followed by an exponential phase. coinciding with squaring flowering and boll development At flowering stage there is a high. demand for moisture nutrients and photosynthates by the developing squares and bolls The. limitation in assimilate supply coupled with the production of hormones such as ABA and. ethylene imposes restriction on the plant to retain only few bolls which mature as open bolls In. this context it is pertinent to know how abiotic and biotic factors affect the canopy leaf area. available for capturing sunlight for the purpose of photosynthesis Fig 1 a 1 b Depending on. the genotypes grown and the time and magnitude of occurrence of abiotic stresses such as. drought waterlogging cloudiness salinity high or low temperature nutrient deficiency etc the. vegetative and reproductive parts of the cotton plant develop various physiological disorders that. either directly or indirectly affect the productivity. Fig 1 Photosynthetic leaf area affected by a abiotic and b biotic stress factors. In view of the economic importance of this crop as well as the recent advances in. scientific applications such as biotechnology nanotechnology it is imperative to know in detail. Technical Bulletin from CICR www cicr org in 5,Physiological disorders in cotton. about the various physiological disorders so as to effectively manage the crop from sowing to. harvest Some of the commonly observed physiological disorders in cotton along with their. symptoms and the options available to minimize their impact are presented in this bulletin. 2 PHYSIOLOGICAL DISORDERS, Physiological disorders appear in cotton as a reflex of plant response to environmental. stresses nutritional imbalances and chemical factors Their effect on productivity depends upon. the crop growth stage intensity of incidence and loss of reproductive parts during ontogeny. However there is a distinct difference between plant adaptation to harsh growing environments. and physiological disorders The various adaptive traits in plants as a response to the stress. environment such as production of small leaves during drought and lenticel formation under. waterlogged condition are not considered as physiological disorders. Some of the commonly occurring physiological disorders in cotton are. Leaf reddening,Parawilt New wilt,Leaf drying burn,Bud and Boll drying. Bad boll opening,Crinkle leaf,Effect of 2 4 D, Bud and Boll shedding A natural phenomenon may be considered as physiological. disorder if the shedding is unusually prolonged and intense due to disturbances in. source sink relationship, Mineral Nutrients deficiency toxicity Though nutrient deficiency toxicity is not.
disorder in strict terms it is worthwhile to know various symptoms because they affect. the plant metabolism and cause various physiological disorders. 2 1 LEAF REDDENING, Leaf reddening in cotton is also known as red leaf disease lal patti This disorder is an. outcome of interaction of location variety environmental condition and nitrogen supply In. general some of the hirsutum varieties and a few inter and intra specific tetraploid hybrids are. sensitive and vulnerable to this malady Apperance of red leaf symptom is primarily due to the. accumulation of anthocyanin pigment Leaf reddening may occur at any growth stage of the. crop However it is quite often confused with the reddening of leaves caused by sucking pest. damage at early growth stages At grand growth phase flowering and boll development any. hindrance in the assimilate production translocation and distribution intensifies the leaf. reddening effect The factors affecting ideal source sink relationship promote leaf reddening and. symptoms are prolific in nature under extreme stress situations. Technical Bulletin from CICR www cicr org in 6,Physiological disorders in cotton. Leaf reddening is initially seen in the mature leaves and gradually spreads throughout the. canopy Fig 2 a To begin with leaf margin turns yellow and later red pigmentation is formed. on the whole leaf area Fig 2b In due course of time the leaf becomes dry and subsequently. prone to shedding,Fig 2a Leaf reddening in the plant canopy. Fig 2b Intensity of leaf reddening as compared to normal leaf. Technical Bulletin from CICR www cicr org in 7,Physiological disorders in cotton. The reddening appears in the plants due to various reasons. Lowered nitrogen level in the leaves below the critical limit due to. Low availability in the soil, Impaired uptake under water deficit and waterlogging conditions.
Diversion of N to the developing bolls, Synchronized boll development and high boll demand. Desiccation caused by high wind velocity,Anthocyanin red pigmentation due to. Abrupt changes or drop in night temperature below 15 C. Nitrogen deficiency,Magnesium deficiency,Chlorophyll degradation. From Table 1 it is clear that reddened leaves had less nitrogen and magnesium contents. It is observed that nitrogen stressed leaves accumulated carbohydrates due to the derailment in its. conversion process As a result there is an increase in C N ratio Similarly these leaves had. predominant accumulation of anthocyanin content, Table 1 Effect of leaf reddening on leaf nitrogen carbohydrate magnesium and. anthocyanin contents in MCU 5 and CBS 156 cotton cultivars. Anthocyanin,Total Total Magnesium,Cultivar ppm congored.
N CHO g 100g leaf,equivalent,Leaf Normal,MCU5 3 8 7 5 1 6 4 0. CBS 156 3 6 7 5 1 2 7 0,Leaf Reddened,MCU 5 3 4 10 0 1 4 6 0. CBS 156 2 5 12 0 1 1 8 0,Management, Adjustment of sowing time for enabling the crop to skip over the adverse environmental. condition during boll development stage,One or two sprays of urea 1 at appropriate times. Application of magnesium sulphate 0 5, Adequate drainage to avoid waterlogging of the fields.
Leaf reddening incidence due to sucking pests may be overcome by spraying. Technical Bulletin from CICR www cicr org in 8,Physiological disorders in cotton. recommended insecticides,Boll load management, Supply of adequate nutrients during flowering and boll development particularly in. Timely inter culture and weeding operations and other agronomic practices. Avoidance of susceptible cultivars,Adequate irrigation if available. Adoption of crop rotation and growing of intercrop to maintain the soil health and. nutritional status,2 2 PARAWILT NEW WILT, In early 1980s a wilt like malady referred to as new wilt or parawilt caused considerable. concern amongst cotton growers across the country It is also called as Adilabad wilt or sudden. wilt Unlike pathogenic wilt which occurs in groups of plants in fields this malady was noticed. to be sporadic random in distribution Fig 3 Hence it is difficult to quantify the incidence. and the yield loss Detailed investigation on isolation distribution pattern and pathogen. transmission proved that fungi bacteria virus and nematodes were not involved in this malady. The etiology of parawilt could not be proved till recently mainly because of its random. occurrence and inability to simulate the wilt under artificial conditions. Fig 3 Field view of parawilt affected cotton plants. The wilt may develop either slow or quick The incidence is particularly high in plants. with large canopy and heavy boll load Fig 4a and 4b In the affected plants leaves show wilt. like drooping become chlorotic and turn bronze or red followed by drying Premature abscission. of leaves and fruiting parts may occur Leaves lose turgidity due to enhanced transpiration. Squares and young bolls are shed and immature bolls are forcefully opened Wilted plants show. Technical Bulletin from CICR www cicr org in 9,Physiological disorders in cotton.
development of anthocyanin pigment Most of the wilted plants gradually recover and produce. new flushes however their contribution to yield is negligible. Fig 4 Parawilt affected plants with a large canopy and b heavy boll load. Cultivation of susceptible varieties hybrids,Higher demand for nutrients and moisture. Prolonged dry spell with high temperature and sunlight followed by soil saturation due to. heavy downpour or irrigation, Wilt incidence is high in heavy clayey and deep soils. Incidence is more in ill drained soils as compared to well drained soils. At CICR Nagpur studies were conducted to create the wilt symptoms under artificial. condition and the causes of wilt were elucidated As presented in the flow chart Fig 5 plants. with large canopy and heavy boll load are more prone to wilting These plants exhibited high. photosynthesis and transpiration rate Table 2 Consequently for the conversion of. photosynthates into proteins and other macromolecules these plants required higher uptake of. nutrients which is an active process and inhibited under anaerobic water logged condition As a. result of the feedback inhibition of root respiration the root system gets degenerated in wilted. plants Damage to the roots caused higher resistance to the mass flow of water through the roots. This coupled with higher transpiration in wilted plants due to their insensitive stomata caused. parawilt in cotton,Management, Planting of wilt tolerant genotypes Wilting was not seen in G arboreum and. G herbaceum genotypes Hybrids like JKHY 1 DCH 32 NHH 44 are wilt sensitive. Technical Bulletin from CICR www cicr org in 10,Physiological disorders in cotton. Varieties such as LRA 5166 LRK 516 Anjali SRT1 MCU 5 VT AKH 4 G 27 and. Jayadhar are relatively tolerant to wilt, Provision of adequate drainage to avoid waterlogging of the fields.
Irrigation if available may be provided during grand growth phase to avoid prolonged. exposure of plants to dry condition, Excessive use of farm yard manure and fertilizers may be avoided in heavy soils. Physiological disorders in cotton PHYSIOLOGICAL DISORDERS IN COTTON PREFACE Cotton known as the King of fibres occupies a unique position in Indian Agriculture Its cultivation dates back to centuries Presently this crop is grown under varying agro climatic conditions It is noticed with distress that innumerable abiotic and biotic factors

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