SHOOT ZONE UPTAKE OF SOIL‐APPLIED HERBICIDES IN PISUM SATIVUM L.

Abstract

Summary. The effects of localized herbicide placement at different internodes of pea (Pisum sativum L. cv. Alaska) shoots below the soil surface after plant emergence were studied by removing the soil from around the shoots and replacing with herbicide‐treated soil. The first internode proved insensitive to linuron, diuron, atrazine and simazine at 4·5 kg/ha, while treatment of the second and third internodes markedly reduced plant growth 4–6 days after treatment. Separate exposure of the first internode alone, and the second and part of the third together to 14C‐labelled atrazine indicated no difference in herbicide metabolism. However, a two‐ to threefold increase in 14C uptake and movement to the foliar parts occurred when the second and part of the third internode was treated, as compared to first internode treatment. Thus the differential sensitivity of the internodes to atrazine, and possibly to the other herbicides, may be because the more mature first internode allows less uptake and subsequent movement to the foliar parts. Absorption dans la zone des tiges des herbicides appliqués dans le sol chez Pisum sativum L.

Effect of soil placement and shoot uptake of prometryne and terbutryne on peas

“…In this study the greatest reduction in plant growth occurred when the herbicide was present in soil at the upper part of the emerging shoot. Similar differences in sensitivity of different parts of the pea shoot were found by Prendeville (1968) and by O'Brien & Prendeville (1972). They have shown that, after plant emergence, pea is not susceptible from exposure of the first internode of its shoot below the soil surface to diuron, linuron, atrazine and simazine.…”

“…Movement of these herbicides from the soil via the ground parts of the plants to the site of herbicidal action is essential for phytotoxicity performance. O'Brien & Prendeville (1972) explain the insensitivity of pea from exposure of its lower internode as a result of the lower shoot being more mature with fuller epidermal and cuticular development. In these experiments pea seedlings were exposed to the herbicides during the germination and emergence processes, and therefore differences in maturity of the different parts of the shoot cannot account for differential susceptibility.…”

“…Nishomoto & Warren (1971) showed that the presence of adventitious roots on the shoot of maize and sorghum were responsible for uptake and injury caused by diuron, ametryne and terbacil. On the other hand, O'Brien & Prendeville (1972) found differences in pea susceptibility from exposure of different parts of the shoot to linuron, diuron, atrazine and simazine; uptake and translocation of atrazine was higher when the upper rather than the lower part of the shoot was exposed to the herbicides.…”

Shoot zone uptake of soil‐applied herbicides in some legume species

“…The above data also indicate that the differential sensitivity of the shoot internodes to soil-applied photosynthesis-inhibiting herbicides, which was evident in the shoot of pea (O'Brien & Prendeville, 1972), is not a characteristic of all legume species. Table 4 Effect of placement of •*C-atrazine (mixed with unlabelled atrazine up to 0-25 mg/kg dry sand) on accumulation of "'C within the plant when applied with and without trifluralin (1 mg/kg dry sand) to the shoot of vetch below the soil surface after emergence ' Each treatment received 0-5 /(Ci of isotope (specific activity 10'2 /iCi/mg)…”

“…In pea, treatment of the first internode with simazine, atrazine, linuron and diuron did not affect plant growth, whereas treatment of the second and third internodes markedly reduced growth. The more mature first internode allowed for less atrazine uptake than the less mature second internode (O'Brien & Prendeville, 1972).…”