Use of Amino Oligosaccharins and Alternaria Activated Protein in Management of Crown Gall and Enhancement of Growth in Roses

Abstract

Rose is cultivated for its beautiful flowers and is considered as the most prized flowers in the world because of its high ornamental and commercial value. The demand for cut flowers has risen in recent years, however, production of cut flowers face many challenges and the most important amongst the challenges is environmental conditions and diseases that hinders production. Crown gall disease caused by Agrobacterium tumefaciens causes a significant damage to roses in Kenya. The study was carried out to determine the effects of a mixture of amino oligosaccharins and alternaria fine proteins on the growth and quality of rose and crown gall disease on roses. The experiment was laid out in a Randomized Complete Block Design (RCBD) with four replications and five treatments comprising of three levels each of amino oligosaccharins and alternaria fine protein (0.5, 1, 1.5g/litre) and copper based fungicide (2ml/ litre) along with control (water spray) in the greenhouse. Crown gall tissues were gathered from four different roses per treatment in the two sites, counted and the size determined and recorded fortnightly. Bacteria were isolated from eight different galls gathered from four different plants. Representative colony types identified via their growth on selective media (MacConkey agar) and growing on nutrient agar media were chosen from each gall sample and sub cultured by streaking on new nutrient agar media. Biochemical test of different isolates was done to identify the bacterial isolates. Data was collected on rose height, number of shoots, disease incidence and severity, flowering duration, stalk diameter, flower head diameter at cut stage, colony types, and on biochemical analysis and was subjected to analysis of variance. There were significant differences in the treatments applied, application of a mixture of amino oligosaccharins and alternaria fine protein at the rate of 1.5g/litre had significant (P≤0.05) effect on number of shoots, plant height, flowering duration, stalk diameter as well as flower head xiii diameter at cut stage. Maximum number of shoots after six weeks 13.6 and 13.9 was recorded in plots treated with amino oligosaccharins at the rate of 1.5g/litre in Winchester farm (Nairobi) and Bahati farm (Nakuru) respectively. However, maximum height (61.3cm) in Winchester and (59.6cm) in Bahati was recorded in plots treated with amino oligosaccharins at the rate of 1g/litre. Plants receiving amino oligosaccharins sprays at the rate of 1.5g per litre recorded significantly (P≤0.05) increased stalk length (27.7cm) in Winchester, (29.6cm) in Bahati and stalk diameter (0.48cm) in Winchester (0.40cm) in Bahati, had shortened flowering duration (19.2 days) in Karen, (11.6 days) in Bahati farm. Application of amino oligosaccharins at 1.5g/litre had significant (P≤0.05) effect on galling formation and reduced the numbers from 2.49 to 1.4 in the eight week and 1.08 in the tenth week in Winchester while in Bahati, the number reduced from 1.54 to 1.03 ten weeks after treatment application. The gram reaction indicates that the selected isolates were gram negative and were positive for catalase, motility, lactose, oxidase, salt tolerance and mannitol tests. Exogenous applications of amino oligosaccharins and alternaria fine proteins in the greenhouse influenced positively the growth of roses and brought about significant decrease in the number of galls and size as well as improvement in plant growth. The ability of the treatments to manage the disease can be attributed to enhanced defense mechanism attributable to amino oligosaccharins and alternaria fine proteins. Key words: Agrobacterium tumefaciens, chitosan, crown gall, oligosaccharins, proteins roses