Abstract:
The distribution, control Aphelenchoides besseyi Christie and 1942 economic on rice importance sativa L) (Oryza cultivars grown in mainland Tanzania was studied. Survey results showed that A. besseyi was widely distributed in stored rice seeds. Hot water treatment (HWT) of dry rice seeds at 54 - 62°C for
In dry seed 15 min effectively controlled seed-borne A. besseyi treatment, exposure period rather than treatment temperature was the
significant factor for the control of seed-borne A. besseyi. Tested
seeds of rice cultivars tolerated dry seed treatment upto 60 0 C' for
20 min in respect of viability, vigour and seedling normality.
Seed treatment at 54°C controlled A. besseyi for but also 15 min following
affected. The sensitivity presoaked rice seeds to HWT was genetically related
following presoaking percentage germination delayed onset, vigour viability,
seedling normality of some rice cultivars and of Seeds treated maximum peak,
presoaking and actual Although HWT of presoaked seeds at 56°C for 15 min completely controlled A. besseyi, it also killed most seeds.
However, HWT of presoaked or unsoaked seeds at 48°C for 20 min did
not affect seed germination and emergence. Significant control of
seed-borne A. besseyi by HWT following presoaking resulted in 10 -
27% yield increases and, larger and/or better quality grains.
Booting stage of rice was the critical stage for control of
A. besseyi for improvement of yield. The fifth day after the first
sign of booting was identified as the most
infection with A. besseyi to adversely critical affect yield stage for attributes.iii
Control of A. besseyi with carbofuran applied at planting and at 50%
booting stage improved rice yield but HWT of A. besseyi-infested
rice seed gave better nematode control and better grain yield. Dry seed treatment to control seed-borne found to be the most appropriate method
because it environment is effective, cheap and safe for to A besseyi Tanzanian the
was farmers; seed and the environment
