Effect of imazaquin applications on the growth, leaf chlorophyll and yield of soybean in the Guinea Savanna of Nigeria

Abstract

Field trials were conducted during the wet seasons of 1989, 1991, 1994 and 1995 to evaluate the effects of pre-emergence and post-emergence applications of four rates of imazaquin (0.00; 0.15; 0.30 and 0.45kg a.i/ha) on the growth, leaf chlorophyll types and grain yield of soybean c.v. SAMSOY 2. Imazaquin applications had no significant effect on the growth of soybean roots on most of the sampling dates, but pre-and post-emergence applications of imazaquin at 0.30 and 0.45kg a.i/ha reduced soybean root nodules at 5 and 7 weeks after planting (WAP). Soybean shoot growth was generally reduced at 5WAP by the pre-emergence and at 7WAP by the higher rates (0.30 & 0.45kg a.i/ha) of post-emergence application of imazaquin. Pre-and post-emergence applications of imazaquin showed a strong tendency to reduce the concentration of chlorophyll a and total chlorophyll at 3 and 5WAP respectively. The concentrations of chlorophyll types in soybean leaves at 9WAP was generally comparable among most treatments especially in 1991. Whole plant fresh weight of soybean at 7WAP was reduced by all rates of post-emergence application of imazaquin. However, there was no significant difference in the whole plant dry weight of soybean at 3 to 7 WAP in 1989 and at 3, 5 and 9WAP in 1991. In each trial, pre-and post-emergence applications of soybean significantly increased the grain yield of soybean compared with the control treatment. This study showed that, inhibition of soybean shoot growth and leaf chlorophyll concentration was transient and that soybean plants require about 6 weeks for complete recovery from imazaquin phytotoxicity.

Photosynthetic Performance of the Imidazolinone Resistant Sunflower Exposed to Single and Combined Treatment by the Herbicide Imazamox and an Amino Acid Extract

“…The appearance of chlorosis in the leaves of imazamox-treated sunflower plants in our study was due to their significantly lower chlorophyll content (Figure 3). This observation is in accordance with the data presented by Alonge (2000) for the decreased chlorophyll a content in imazaquin-treated soybean plants as well as imidazolinine herbicide treated sunflower and wheat plants (Pozniak et al, 2004; Ochogavía et al, 2014). …”

Biotoxic effects of the herbicides on growth, seed yield, and grain protein of greengram

“…Moreover, the decreased supply of photosynthate to the roots due to totoxic action of atrazine and metribuzin and the direct effects of these herbicides on the growth of Bradyrhizobium in vitro might have resulted in the reduction of functional symbiosis. The data from this study thus supported the concept that the detrimental effect of atrazine and metribuzin is primarily bacterium mediated that resulted in the indirect effects on nodulation and yield (Alonge, 2000). Seed yield increased marginally with 200 and 400 µg.a.i.kg -1 of sulfosulfuron while atrazine and isoproturon, at the same rates significantly (P ≤ 0.05) declined the seed yield compared to control.…”

Influence of herbicides on Chickpea-Mesorhizobium symbiosis

“…The ND and 2D rates of the other herbicides, however, did not show any significant effect on photosynthetic pigments at 90 d after seeding the chickpea, as compared with control. Other studies have also shown an inhibition in shoot growth and chlorophyll concentration following pre-emergence and post-emergence applications of four rates of imazaquin to soybean [3]. The 10D rates of each herbicide, in general, showed significant reduction in shoot N at both stages of plant growth.…”