The effects of Butralin herbicide (2.5 L/fed), H2 and manual
hoeing twice, H3 (at 30 and 60 days age) together with three hill
spacing (10 (D1), 15 (D2) and 20 (D3) cm between hills) on vegetative
growth, chemical composition, yield and yield components and quality
traits of two soybean cvs (Giza 111, V1 and Giza 21, V2) and associated
weeds, were of interest of the present work. The study was carried out,
through split split-plot design at experimental farm of the Fac. of
Agric., Fayoum univ., during 2006 and 2007 seasons. The results
showed that both Butralin herbicide (H2) and manual hoeing (H3) weed
treatments surpassed the unweeded one (H1) in controlling weeds in
soybean field. Suppression ratios of weed growth due to manual hoeing
(71.3 to76.3%) for broad (BFW), narrow (NFW) leaved and total weeds
were higher than that of Butralin (60.19%) for only narrow leaved
weeds. Hill spacing significantly affected BFW and total weed weight
in the first sample in favor to the closest spacing (D1) which resulted in
30.3 and 36.2% weed excision, respectively, over the widen spacing
(D3). The results indicated that hill spacing had lower effect than weed
control treatment on weed growth. There was no significant effect of
soybean varieties on weed growth. H2 D2 V2 and/or H3 D1V2 exhibited
the lowest NFW. In respect to chemical constituents of soybean plants,
H2 and H3 markedly exceeded H1 treatment, in favour to H2 for most
estimates, with similar values for phenols, carotenoids and anthocyanin
with those of H3. Hill spacing showed overlapping effect on chemical
constituents, in favour to the intermediate plant density D2 (15 cm) and
/or D1 (10 cm). H2 D3, H2 D2, H3V2 as dual interaction as well as H2 D3
V2, H3 D1 V1 and H2 D2 V1 as trio-interactions were of great positive
effects on chemical constituents of soybean plants. Regarding yield and
its components, H3 treatment produced highest values for yield and its
components, while H2 increased vegetatively, i.e. plant height. Narrow
spacing (D1) increased numbers of branches and pods and weight of
pods, plant seeds and seed yield/fed. Intermediate plant density gave
branches and seed yield/fed similar to those of D1. V2 outweighed V1 in
yield and its components where is the reverse was true for plant height.
Positively effective interactions were H3 D1, H2 V2 and H3D1V2, on
weights of pods, number of seeds/plant and seed index. The highest
percentages of carbohydrates (23.37), protein(48.10) and oil(22.38%)
were recorded by H3D3V2, H2D1V1 and H2D3V1, respectively. The
absolutely highest seed yield/fed (1.89) in such newly reclaimed land
was obtained by Giza 21 (V2) planted in closest hill spacing D1(10cm ,2
plants/hill) and treated by manual hoeing twice.