in order to effect of different mulch materials and optimal chemical, organic and biological fertilizer management on ecological agriculture characteristics in common purslane (portulaca oleracea l.) in khuzestan conditions, a filed experiment was conducted at experimental field of ramin agriculture and natural resources university in ahwaz, south-western of iran, during 2010- 2011 growing seas...

1 We present results from a long-term sowing experiment conducted in nutrient-poor savanna grassland in eastern Minnesota. We examine the effects of a one-time seed addition of 23 grassland species on plant community dynamics and structure over eight growing seasons. 2 Our goals were to: (i) test the importance of seed availability in regulating plant colonization dynamics and species richness;...

Agents responsible for tosses of conifer seed and methods for seed protection are reviewed. Published information indicates that much seed is destroyed, especially by seedeating rodents and birds. Improvement of existing protective methods and development of new chemical means are necessary to overcome the problem.

This paper considers strengths and weaknesses of the informal and formal seed as a basis for seed sector development. The informal seed sector is defined as the total of farmers’ seed production, selection and seed exchange activities. Farmers play an important role in seed supply but they are generally not considered as a partner in the seed sector. Seed produced by farmers is still the most i...

Ð Although there has been a considerable growth of private seed enterprises in developing countries, there are few examples of the private delivery of seed of public crop varieties that are not hybrids. This paper discusses the example of rice in Andhra Pradesh, where private enterprise is supplying an increasing proportion of the seed used by farmers. The institutional conditions for private e...