Table 1 showed non-significant effect of sowing methods but significant effect of
weed-crop competition periods on total weed population. The number of weeds went on
increasing with subsequent increase in weed-crop competition periods. The significantly
more number of weeds i.e., 215.25 and 93.38 m-2 was recorded in weedy check during
2005-06 and 2006-07, respectively, followed by 105 DAS weed-crop competition.
Trench sowing showed statistically significant total biomass (288.71 and 304.47 g m-2)
than flat sowing during both the years. As regards weed crop competition periods, the data
(Table 1) disclosed the fact that total biomass of weeds went on increasing significantly
with 15 days increase in each weed-crop competition period from 45 DAS to harvest.
However, all weed crop competition periods gave statistically more biomass of weeds than
zero competition (full season weed free) during each year of study.
Sowing techniques significantly affected the leaf area index of sugarcane at maturity
during both the years of investigation (Table 2). The trench sowing technique by giving
7.48 and 7.29 leaf area index of sugarcane statistically surpassed the flat sowing
technique during 2005-06 and 2006-07, respectively.
The weed-crop competition periods affected the leaf area index significantly during
each year of investigation. The highest leaf area index of sugarcane was computed for
crop kept weed free (zero competition) throughout the season and it was immediately
followed by crop, which faced weed competition up to 45 days after sowing during both
the years of study. Significantly, the minimum leaf area index of sugarcane was
calculated for crop, which faced full season weed competition (weedy check).
The data regarding average crop growth rate (ACGR) given in Table 2 reflected that
sowing techniques affected ACGR significantly in 2005-06, but effect was not significant
during 2006-07. The data revealed that trench sown sugarcane exhibited significantly
more ACGR (7.32 and 7.90 g m-2 day-1) than flat sown crop, which showed 7.21 and 7.68
g m-2 day-1 in 2005-06 and 2006-07, respectively. Weed-crop competition period
significantly reduced the ACGR during both the years of study. Weed competition free
crop (zero competition) by giving 8.12 and 8.85 g m-2 day-1 ACGR in both the years
proved significantly better than crop facing weed competition up to any duration till
harvest (weedy check). Reduction in ACGR was recorded with increasing the weed crop
competition during both the years of study.