index of the size and plumpness of air-dried seeds expressed in grams. The weight of 1,000 seeds varies greatly for different plant species—for example, for broad beans it is 1,200 g and for poppy seeds it is 0.4 g. The weight also differs for different varieties of the same species. The weight of 1,000 seeds is determined in order to calculate correctly the rate of seeding. In special seed-growing research the weight of 1,000 seeds is converted to dry, waterless matter in order to compare two seed samples; the absolute weight of the seeds is thus determined. The weight of 1,000 seeds is influenced by meteorological factors, methods of farming, and the like. In periods of drought and moisture deficiency in the soil, undersize and lightweight seeds develop on plants. Lodging of stalks, infection of plants by disease, and pest damage have negative effects on the weight. The agricultural methods used in seed fields should promote an increase in the weight of 1,000 seeds. Providing plants with moisture and nutrients are the most important factors.