Periode Kritis Tanaman Tomat terhadap Serangan Alternaria solani (Ell. & G. Martin) Sor. dan Faktor Penentunya

Abstract

Determination of critical period (susceptible period) of plant is one of the strategies in Integrated Pest Management (lPM), because it can reduce or minimize pesticide use. Study about the critical period of tomato was carried out in the field of Bangbayang Village, in the Cicurug district of SulaJbumi. 1bmato plant cultivar Intan at different age (50, 60, 70 and 80 days after sowIng [DAS] were inoculated with 15 ml of ul sporelml suspension of Alternaria solani per plant, that have been added with Agristick 2% and 7Ween 80 2%. Observation that was conducted include disease severity, the height of plant, dry weight of plant biomass and total fruit production. Leaves of different age (50, 60, 70, 80 DAS) at different part of plant (lower, middle and upper canopy) were analyzedfor total protein by Auto Analyzer II Method, total phenol by Follin- Denis Method and total sugar content by Luff-Schoorl Method. The result showed that the older plant have the higher disease severity. The same trend can he seen from the age of leaves i.e. leavesfrom th~ lower part of plants (older) are more susceptible than the middle and upper leaves. The critical period of the plant is at the age of 50 - 60 DAS. Total fruit production is not determined by disease severity, instead it is more determined by the age of plant infected. There is a tendency that the interaction among total protein and phenol content effect the susceptibility of the plant to the pathogen as can be seen the following regression equation: Y = 167 - 3.19 X2 - 22.58 X3 (R =0.76). Key words: Critical period, Alternaria solani, disease severity, protein, sugar and phenol total content