RESPONSE OF TWO SOYBEAN CULTIVARS AND THE ASSOCIATED WEEDS TO SOME AGRONOMIC FACTORS UNDER NEWLY RECLAIMED SOIL

Individual and integrated effects of three weed control treatments H [weedy control (H1); Butralin (H2) and manual twice hoeing (H3)] , three hill spacing , D [10 (D1), 15 (D2) and 20 cm (D3)] and two soybean varieties, V [ Giza 111 (V1) and Giza 21 (V2)] on dry matter (DM) of associated weeds, growth traits and parameters, nutrients uptake and seed yield, were the intended aim of the present study. To achieve this aim, split- split plot arrangement was used, where tested variables; H, D and V were allocated in main-, sub- and sub-sub plot, respectively, at newly reclaimed soil of the experimental farm "Demo" of Fac. Agric., Fayoum Univ., during 2006 and 2007 summer seasons. The obtained results could be summarized as follows: Dry weight of weeds were deppressed by twice manual hoeing, dense planting, chemical control and the interaction of H2D2V2 in the first sample and H3 V1 in the second sample.Maximum values of soybean height, number of branches, LA and LAI were obtained by H2 or H3 depending on the sample as well as the studied variety. Soybean density had a significant effect on plant growth (height, DM and LA). In addition CGR and NAR as well as N, P, and K were affected by H3 and H2. Several dual and triointeractions significantly affected the growth traits. Manual hoeing, H3 (1490 kg/fed) out yielded Butralin treatment, H2 (1000kg/fed) and both surpassed the weedy control one, H1 (530 kg/fed). Closest spacing, D1 (1080 kg) followed by intermediate one, D2 (1060 kg) produced markedly by higher seed yield/fed that of the widest spacing (890 kg). V2 (1080kg) out yielded V1 (940 kg/fed). H3 D1 (1840), D2 V2 (1500) and H3D2 (1260) as well as H3D1V2 (1890 kg/fed) were the most effective interactions on soybean yield. The obtained results revealed that, in such newly reclaimed land, the maximum yield with improved quality of soybean could be obtained from Giza 21 planted in closed spacing (10cm) and treated with manual hoeing twice.