Potato (Solanum tuberosum) greenhouse tuber production as an assay for asexual reproduction effects from herbicides

Abstract

The present study determined whether young potato plants can be used as an assay to indicate potential effects of pesticides on asexual reproduction. Solanum tuberosum (Russet Burbank) plants were grown from seed pieces in a mineral soil in pots under greenhouse conditions. Plants were treated with herbicides (cloransulam, dicamba, glyphosate, imazapyr, primsulfuron, sulfometuron, or tribenuron) at simulated drift levels [</=0.1 x standard field application rates (f.a.r.)], approximately 14 d after emergence (DAE). Plant height was measured approximately 14 d after treatment (DAT). Production of small tubers and shoot dry weight were determined at approximately 28 DAT. Imazapyr, sulfometuron, and tribenuron caused significant reductions in tuber fresh weight, with the effective concentrations producing a 25% potato tuber fresh weight (EC25) of 0.00038, 0.0016, and 0.0021 x f.a.r. of 1,124, 52, and 9 g active ingredient hectare(-1) (g a.i. HA(-1)), respectively. Primisulfuron, dicamba, and cloransulam also significantly reduced tuber fresh weight, but with higher EC25 values of 0.011, 0.07, and 0.010 to 0.2 x f.a.r. of 40, 558, and 18 g a.i. HA(-1), respectively. Glyphosate had little effect on tuber fresh weight, with a significant reduction in only one experiment. Sulfometuron reduced tuber fresh weight at an EC25 value lower than the EC25 values for shoot dry weight or plant height. For other herbicides, the reduction in tuber fresh weight occurred within the range of EC25 values for other responses. Although additional experiments are required to develop further a phytotoxicity test, these results indicated that tuber production in young potato plants (harvested approximately 42 DAE) may be an effective assay for below-ground asexual reproductive responses to herbicides, especially acetolactate synthase inhibitors.

Selectivity of the plant growth regulators trinexapac-ethyl and sulfometuron-methyl to cultivated species

“…The importance of measuring tuber production and not just vegetative shoot growth as an indicator of risk from low levels of herbicides was highlighted by the response of the young potato plants to sulfometuron. There was a much greater effect on tuber yield than on vegetative growth, measured especially as shoot dry weight (Olszyk et al, 2010). In this study, the results indicated that the sulfometuron had an influence on the source-sink relation of the potato plant and this caused the partition process to be unbalanced resulting in an accumulation of photosynthates in the plant aerial part.…”

“…In another study, soil residues of sulfometuron larger than 240 parts per trillion caused distorted tubers with cracks and folds (Hutchinson et al, 2007). Olszyk et al (2010) also observed that treatments with low levels of sulfometuron caused large reductions in tuber fresh weight. The effect on tuber fresh weight was due to reduced tuber size, insofar as it did not affect the number of tubers.…”

Comparing effects of low levels of herbicides on greenhouse- and field-grown potatoes (Solanum tuberosum L.), soybeans (Glycine max L.), and peas (Pisum sativum L.)

“…Al-Khatib and Tamhana [24] found reproductive losses with pea plants exposed to low levels of chlorsulfuron or metsulfuron but with more severe vegetative visible injury than noted by Fletcher et al [15]. Olszyk et al [22] did not find any consistent pattern in herbicide sensitivity at various stages of pea plant development, but confirmed that pea plants can have reduced seed yield with sulfonylurea herbicides.…”

“…Regardless of the environment in which we have grown potatoes, peas, and soybeans (large pots inside and out in the present study, small pots [22], or in the field [20]), the EC25s have generally been within a single order of magnitude for a particular species, herbicide, and response. Riemens et al [23] found differences based on herbicide used, with greenhousegrown plants being more sensitive to glufosinate ammonium, while field-grown plants were more sensitive to tepraloxydim.…”

“…At least five months are required to produce mature tubers, which increases the costs over the standard vegetative vigor test [14]. In an effort to overcome these problems in using potatoes as an asexual reproductive test plant, a series of experiments were conducted using potatoes grown in small (2.5 L) pots for 42 d after emergence [22]. These experiments confirmed that small potato plants grown for just three weeks longer than the standard vegetative vigor test produce small tubers that can be used as a bioassay for herbicides, and possibly for other pesticides on belowground, asexual reproduction [22].…”