The mean time for 50% germination at 20 8C of 12 Indian wheat (Triticum aestivum) cultivars was nearly halved, from 51 h to 27 h, by soaking seed in water for 8 h prior to sowing. A delay of 24 h without further soaking, intended to simulate postponement of sowing, reduced the time saved by priming to 16%. Priming had no effect on ®nal germination percentage. These results were used in the design of 275 on-farm, farmer-managed, participatory trials of seed priming in wheat during the 1997±98 and 1998±99 rabi (post-monsoon) seasons.In forty-one trials in tribal areas of Bihar and West Bengal states of India, seed priming gave a 13% grain yield advantage for farmers growing wheat in marginal areas with low levels of agricultural inputs. Mean bene®ts from seed priming of wheat in nine trials in Chitwan, Nepal were 17%. In high potential areas of Gujarat, India, 205 trials had higher rates of input use. Yield bene®t from priming in these trials averaged only 5% but constituted an extra 200 kg ha 71 grain at little or no cost. In 20 trials on marginal land, with slightly saline irrigation water in Ahmadwala, Pakistan, an average yield increase of 36% was obtained using seed primed with a 0.2% gypsum solution. Collaborating farmers reported that priming wheat seed overnight resulted in faster, more complete emergence, more vigorous early growth, better tillering, earlier owering, larger ears, earlier maturity and higher yields. In addition, many farmers also reported that foliage in primed plots was a darker shade of green than that in non-primed plots, suggesting that primed plants may have been using nitrogen more ef®ciently.Seed priming was popular with farmers, most of whom reported that they would prime wheat seed the following year. A survey in Gujarat in 1998±99 of 63 farmers who had tested priming in 1997±98 showed that, while 65% had primed some of their own seed, none had primed more than 50 kg, suggesting that there were practical dif®culties in priming larger volumes of seed.introdution Wheat (Triticum aestivum) is grown widely in South Asia in the rabi (post-monsoon season) after the harvest of kharif (rainy season) crops (Hobbs and Morris, 1996).
