Relationship between bacterial blight development and rice crop growth
1990
Jin, K.S.
Bacterial blights infection at early growth stage of the plants grown at high nitrogen (N) level has reduced leaf area than the plants infected at later growth stage under lower N level, regardless of secondary infection and similar % of disease plant area (% DPA). The reduction of leaf area decreased with increasing resistance of varieties. Dry weight accumulation of the rice plants for all cultivars decreased as a result of BB [bacterial blight] infection on the upper leaves, at panicle primordia initiation stage (60-70 DAS) and grown at high nitrogen level. The gaps in dry weight between healthy and BB infected plants increased continuously with time until harvest, when the rice plants were infected at early growth stages. The decrease in root dry weight due to BB infection was significantly different between the healthy and infected plants, and increased with time and susceptibility. BB infection on the upper leaves reduced grain yield due to reduction of filled grains. The grain yield of plants grown at high N levels, infection at 60-70 DAS was less than that of plants infected at earlier than 60 DAS or later than 70 DAS and grown at low nitrogen level. The reduction was associated with the reduction of panicles per hill, grains per panicle, % of filled grain and 1,000 grain weight under the condition of the lack of the secondary infection. Infection of upper leaves before flowering resulted in a decrease of harvest index (HI) of IR56, IR36, and IR72. When the fourth leaf was infected, HI was decreased. HI of IR56, IR36, and IR72 plants infected after flowering and IR66 at 70-90 DAS was also increased.
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