Rose Diseases And Pests

POST-HARVEST TECHNOLOGY   

Shape, sixe and color of the rose flower should be representative of the cultivars. According to the market demand and the type of flowers, the stem length of rose cut flowers varies front 15 to 120 cot. Healthy, normal and bright foliage is important. The flowers with uniform stage of development and uniform stem length are preferred. They should, however, be strong and straight and capable of holding the flowers in upright position. (Bhattacharjeo and De, 2005)

VARIABILITY DUE TO INHERENT AND GENETIC FACTORS

Wide differences in the post harvest life and quality of roses have been observed among different species of flowers (Hhattachaffee and Savona, 1998) and among cultivars of the same species (Bhattachalee, 1994). Wide variability irr the thirty-two cultivars of cut roses was observed in water uptake, vase life, weight loss and flower diameter. (De et. al., 1999). The D2values were significant among these thirty-two cultivars, which were grouped into eight clusters. For vase life, the varieties "Angelique", "Golden Times", "Raja S. S. Singh of Nalagarh", "Sandra" (Cluster IV) and "Sonia Mei/land" (Cluster VII) were best. On the other hand, varieties of cluster IV ("Raja Ram Mohan Roy" and "jawani") had shown the highest flower diameter. Different cultivars vary in thee stem diameter and rigidity, which ultimately affect the post harvest life (Nowak and Rudnicki, 1990). Variation in vase life among different cultivars has been attributed to differences in number of thick wall supporting cell in the xylem elements and phloem fibre and presence and absence of complete ring of secondary thickening in flower peduncle (Zamski et. al., 1991). Even stomata' activity especially poor closure of leaves can affect flower vase life (Mayak Cf. al.. 1974). Variation in water uptake among different cultivars of flower is due to differences in the leaf diffusive resistance of leaves in the field Cod°, et. al., 1989) or differences in bacterial or fungal species gaining predominance in the vase water (De Stigter and Broekhayson, 1986). Increment of vase life of cut flowers ntay also be due to higher activity of peroxidase, phenylalanine- ammonialyase and lignifications (Zeislin and Ben- 'dukes, 1991). Furthermore, variation in vase life, weight loss, flower diameter among different cull:biers may be due to differences in senescence behavior by producing higher amount of ACC, ethylene forming enzyme and ethylene (Wu et. al., 1991) and due to genetic make up of the cultivars (Gelder, 1989). Hence, there is an ever ending need for evaluation of all emerging rose cultivars on the basis of their post harvest quality and longevity, apart from a definite breeding programme in this direction.

SENESCENCE AND POST-HARVEST PHYSIOLOGY

A sequence of changes in flower physiology lead to senescence- and these are changes in membrane lipids, a rise in ethylene production and loss of differential permeability generally reflected in in in ion leakage and finally a reduction in weight due to excessive water loss. The leakage of cell constituents due to loss of structural integrity of the cell membrane results in death of flower.

PHYSIOLOGICAL CHANGES DURING SENESCENCE

The longevity of cut flower" in flower vase depends on the rate of transpiration through open stomata of the leaves and the solutes present in the vase water (Van Doom, 1997). Aluminum compounds reduce the transpiration of rose cut flowers by decreasing.

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