EFFECT OF PENDIMETHALIN AND IAA TREATMENTS ON GROWTH, YIELD, CHEMICAL COMPOSITION OF COWPEA (Vigna sinensis L.) AND ASSOCIATED WEEDS AT NOBARYA

Two field experiments were conducted at the newly reclaimed sandy soil of
Nobarya in 1998 and 1999 seasons to study the effect of using the herbicide
Pendimethalin (Stomp) at the rate of (0.0,0.9 and 1.7 Ufed.) and 1M at (0.0,12.5-
25.0 and 50.0 ppm) as well as their different combinations on associated weeds,
plant growth and yield components of cowpea plants in addition to the chemical
composition of seeds. Pendimethalin alone or in combination with 1M significantly
depressed the growth of weeds as compared with untreated plants. Treatment of
Pendimethalin at the rate of (1.7 Ufed.) + 1M at (25 ppm) was effective in depressing
the fresh and dry weight of total weeds at 50 and 75 days after sowing followed by
Pendimethalin (0.9 Ufed.) + 1M at (25 ppm). On the other hand, 1M treatments
alone were less effective. All Pendimethalin and 1M treatments caused significant
increase in plant growth and yield characters. The results showed that the plant
height, No. of leaves, branches, No. of pods, seed, dry weight of plant yield/plant,
weight of 100 seed and seed yield (kg/fed.) were significantly increased by the
application of Pendimethalin and 1M than the control treatment which produced the
lowest values of seed yield. Total protein %, carbohydrate % as well as the content of
N, P, K, Zn and Mn in cowpea seeds were increased by all treatments. The highest
increase was recorded by Pendimethalin at (1.7 Ufed.) + 1M at (25 ppm).