6.97
SEED-HEALTH STUDIES IN WHEAT (TRITICUM AESTIVUM) IN KENYA

R WANYERA

KARI-NPBRC, Njoro, Kenya

Background and objectives
Wheat (Triticum aestivum L.) is among the nine crops of major importance propagated by seed [1]. In Kenya, wheat is among the grain cereals that contribute significantly to food security. It ranks second only to maize [2]. Severe attacks of diseases have been reported in the ecological zones where wheat is grown. Foliar and seedborne diseases such as yellow rust, brown rust, stem rust, blotches, smuts and barley yellow dwarf virus have been reported [1]. The importance of devastating diseases, such as smuts, bunts, Bipolaris sp., Fusarium sp., Septoria sp. and nematodes has been studied elsewhere, but not in Kenya. The impact especially of seedborne diseases on wheat seed and seedlings has not been determined. Therefore the objective of this study was to make a survey of the seedborne fungal diseases on wheat in Kenya with emphasis on abnormal seedlings and ungerminated (dead) seeds after germination in the laboratory.

Materials and methods
64 seed samples of 18 introductions and 20 cultivars of wheat grown in some parts of the wheat-growing areas of Kenya were analysed for germination and fungal pathogens in the laboratory. Germination testing by the sand method was according to the International Seed Testing Association rules. A sub-sample of 800 seeds were tested for each sample, half of the subsample (400) seeds was treated with a fungicide, Raxii 025 FS (tebconazole) at the rate of 3 g a.i. per 100 kg seed. The seeds were mixed with a fungicide in flasks, thoroughly shaken and left for 12 h before planting. Another half of the sub-sample (400) seeds was not treated. There were four replicates of 100 seeds for each treatment. At evaluation, three categories, normal seedlings, abnormal seedlings and ungerminated (dead) seeds, were recorded [2]. The blotter method was used to analyse fungal pathogens on the abnormal seedlings and ungerminated (dead) seeds.

Results and discussion
Percentage germination of normal and abnormal seedlings showed significance (P<0.05) among the cultivars and lines. The highest germination of 98.5% was recorded on cultivar Kenya Fahad (acc. no 39/96) and lowest on cultivar Duma (29.25%) (accession no. 11196). The blotter method indicated the presence of Phoma sp., Bipolaris sorokiniana, Fusarium moniliforme, F. equiseti, F. graminearum, F. semitectum, F. oxysporum, F. solani, Fusarium sp. and Bipolaris sp., with several fungi in the abnormal seedlings and ungerminated seeds. Some of these fungi, B. sorokiniana, F. graminearum and F. moniliforme, are known to cause severe damage to wheat seeds and seedlings in other parts of the world. Phoma sp. has also been reported as an important pathogen of wheat in other parts of the world. The importance and impact of the identified seedborne fungi on wheat should be quantified in the wheat-growing areas of Kenya to ensure good quality seed and high production.

References
1. Neergard P, 1979. Seed Pathology. p. 3 2. Kenya Agricultural Research Institute, 1991. Kenya Agricultural Research Priorities to the year 2000.