Spatial relationships between weed seed bank, and population and their distribution models in sugar beet crop (Beta vulgaris)

Abstract

A field experiment was conducted to study the spatial relationships between weed seed bank and population and their distribution models in sugar beet crop (Beta vulgaris) in 2009 at Motahari Agricultural Research Station of Karaj. Sampling from seed bank before sugar beet drilling and weed population in three stages during the growing season were done using square (50*50 cm) and rectangle (25*100 cm) frameworks. Seed and plant frequency of each weed species were recorded in the both frameworks. Geostatistics technique was used to investigate the local structure of the weeds and dynamic of the spots. Amaranth, lambsquarter and narrow-leaf weeds were the prevalent weed species in the field. Semi-variogram analysis showed a range of influence from 0.24 to 141.9 m depending on weed species and sampling stage. The highest range of influence belonged to amaranth, especially in the second stage of seedling sampling. Lambsquarter had a lowest range of influence between all weeds. The highest nugget effect (1.671 and 1.308) was observed for amaranth (at second sampling from seedlings) and narrow leaf-weeds (at the first sampling from seedlings), respectively. This led to weak local correlation for amaranth and narrow-leaf weeds. Strong local correlation was recorded for seed and seedling of lambsquarter at all sampling stages. Spot distribution of weeds was confirmed by local distribution maps. Spots structure changed during the growing season. Results suggested that weed local distribution could improve management decisions and comprehension of dynamic of weeds populations.

Keywords

• amaranth seed bank
• distribution pattern
• dynamics of weeds populations
• geostatistics
• lamb's quarter