Effect of herbicides on growth, nodulation and nitrogen content of greengram

Almas Zaidi , Md. Saghir Khan , Pervez Qamar Rizvi

We studied the effects of glyphosate, metribuzin, fluchloralin and 2,4-dichlorophenoxy-acetic acid (2,4-D) on plant vigor, nodulation, photosynthetic pigments, N content, seed yield and protein content in seeds, in greengram inoculated with Bradyrhizobium sp. (vigna). The pre-emergence application of the four herbicides, at 2 mg a.i. g-1 of soil, adversely affected the parameters. The average maximum increase of 12.5% in seed yield occurred at 0.5 mg a.i. g-1 of glyphosate, while metribuzin at 0.5 and 1 mg a.i. g-1 decreased the seed yield by 33.3 and 55.5%, respectively. The average maximum chlorophyll content of 3.41 mg/g was obtained at 0.5 mg a.i. g-1 (fluchloralin), which declined consistently for all herbicides and increasing dose rates. Glyphosate at 0.5 mg a.i. g-1 increased the number of nodules formed per plant by 12.5% and 14.3% at 35 and 60 days after seeding the greengram. In contrast, metibuzin (0.5 and 1 mg a.i. g-1) and the higher rates of 2 mg a.i. g-1 of glyphosate, fluchloralin and 2,4-D significantly reduced the nodulation (nodule number and dry mass). The average maximum grain protein of 24% was obtained for glyphosate at 0.5 mg a.i. g-1 while minimum grain protein was obtained at 0.5 (10%) and 1 mg a.i. g-1 (8%) of metribuzin application. Nitrogen content in whole plants decreased gradually with herbicide rates both at 35 and 50 days after seeding. Among the herbicides tested, metribuzin showed a large degree of phytotoxicity to the crop, inhibiting its vegetative growth, and was thus incompatible with greengram.

Mots clés: greengram; herbicides; nodulation; seed protein

Domaines: Sciences agricoles; Ecologie, Environnement

Almas Zaidi, Md. Saghir Khan, Pervez Qamar Rizvi. Effect of herbicides on growth, nodulation and nitrogen content of greengram. Agronomy for Sustainable Development, 2005, 25 (4), pp.497-504. ⟨hal-00886309⟩