SOIL WEED SEED BANK STATUS IN THE AGROECOLOGICAL CONDITIONS OF CHITRAL, PAKISTAN

Abstract

A greenhouse experiment was carried out at the Agricultural Research Station (ARS), Shen Lasht, Chitral during 2016-17. There were five different locations in district Chitral from where the soil samples were collected which included Drosh, Shen Lasht, Garam Chashma, Ayun and BoonyLasht. A total of 300 samples were collected from all locations with 60 samples from each location. The 300 soil samples collected were placed in trays of medium sizes i.e. 27 cm x 21 cm x 4 cm = 2268 cm3. The trays were arranged in three repetitions having 100 samples in each repetition. Each repetition of 100 samples contained samples from 5 locations, in each location 4 sites (east, west, north and south each at 100 m distance from each other) and at each site samples were collected from 5 different depths, making a total of 100 samples in one repetition i.e. 5 x 4 x 5 = 100 and with repetitions making a total of 300 samples in one district. The results indicated that in the soil samples of district Chitral a total of 31 noxious weeds were recorded. Out of the 31 different weeds, 23 were broad leaves, eight were grasses and one was sedge. In another angle, 24 weeds were annuals while the rest were perennials out of the 31 weeds identified. A total of 17 different plant families were represented by the weeds recorded in the soil samples of Chitral region. Among the different locations of Chitral, the highest weed seed bank was recorded in the soil samples of ARS Shen Lasht area. Weed seed banks have always been higher in areas with mild winters, where the Shen lasht area is having milder winters as compared to the other areas in Chitral. The lowest seed bank was recorded in the soil samples of Garam Chashma, which was however statistically at par with the rest of the locations studied in Chitral. As far as the seed banks in the depths are concerned, largest weed seed bank was observed in the depth of 6 to 12 cm. The smallest seed bank was at the depth of 30 cm followed by the depth of 24 and 18 cm. Therefore, it is evident that the major weed seed bank lies in the upper 6-12 cm depth of the soil. In case of the interaction, the largest weed seed bank was recorded at ARS Sheen lasht at the depth of upper 6 cm of the soil profile whereas the weed seed bank was very low below the 12cm depth of soil upto 30 cm in the Garam Chashma area of Chitral. Out of the total 31 weeds recorded in soil samples of Chitral, the top 10 weeds in terms of the relative weed densities, relative weed frequencies and importance value indices were Convolvulus arvensis, Rumex crispus, Poa annua, Galium aparine, Avenafatua, Trianthemaportulacastrum, Silybum marianum, Sorghumhalepense, Euphorbia helioscopia, and Loliumtenulentumspecies. The IVI values for these weeds were 14.01, 13.96, 13.07, 11.83, 11.57, 11.12, 10.35, 10.09, 10.02, and 9.99, respectively. Moreover, these IVIs indicate that out of the topmost 10 problematic weeds eight weeds are broad leaved and two are grassy weeds.