Studies on the physiology of plants infected with cocoa swollen shoot virus

The relatively low levels of tolerance of CSSV found in recent field variety trials together with the demonstration that the levels of resistance may be sufficiently high to be of practical importance has led to emphasis being placed on resistance rather than on tolerance in the breeding programme. In an attempt to elucidate the cause of this set-back in the development of tolerance, a series of investigations designed to give information on physiological factors affecting tolerance and on the physiological effects of infection were conducted, the results of which are summarised and discussed. Environmental effects on tolerance were shown to be considerable, exposed plants being particularly severely affected. Though fertiliser has been shown to enhance tolerance in mature trees, the nutrient status of young plants in sand culture did not significantly influence the effect of virus infection. There was evidence that micro-nutrient deficiency, particularly of zinc, interacted with virus to reduce tolerance to a very low level. Excess moisture and poor root aeration led to low degrees of tolerance. The importance of the stage of growth at which infection occurs on tolerance has not yet been assessed, but some of the most tolerant trees known were infected at an early age. CSSV decreased growth and photosynthesis, but infected plants grown in conditions favourable for the expression of tolerance showed a recovery in growth rate after 6 months. Infected plants were shown to suffer from higher degrees of internal moisture stress during sunny periods than the controls. In seedlings, carbohydrate accumulated in the leaves of infected plants, translocation rate not being appreciably affected

Bibliographic Details

Main Authors:	Jones, Earl 81495, 107834 Quesnel, V.C., 56331 Chalmers, W.S., 68473 Fordham, R., 80036 Iton, E.F. eds., 79336 Hutcheon, W.V., 97646 Murray, D.B., 5330 Cocoa Research Institute, St. Augustine (Trinidad y Tobago), 4. International Cocoa Research Conference St. Augustine (Trinidad y Tobago) 8-18 Ene 1972
Format:	biblioteca
Published:	St. Augustine (Trinidad y Tobago) 1972
Subjects:	THEOBROMA CACAO, VIROSIS, RESISTENCIA A LA ENFERMEDAD, FISIOLOGIA VEGETAL, CAMBIO CLIMÁTICO, DEFICIENCIA DE MINERALES, FOTOSINTESIS, AGUA DEL SUELO, CONTENIDO DE AGUA EN EL SUELO, LUZ DEL DIA, COCOA SWOLLEN SHOOT VIRUS,
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