Cucurbit Genetics Cooperative Report 4:35 (article 17) 1981
Segregation for Resistance to Trifluralin Toxicity in
Progeny from Crosses of Susceptible Cucurbita moschata
Parents
Adeoye A. Adeniji and Dermot P. Coyne
University of
Nebraska, Lincoln, NE 68583
Several herbicides are reported to be selective in cucurbits
when soil-incorporated (1, 2). Among these are the dinitroanilines,
for example, trifluralin (treflan). A recent finding by
us on the response of progeny derived from crosses of susceptible
cultivars of Cucurbita moschata to trifluralin
indicated physiological variation in response to this herbicide.
The three susceptible parental cultivars used in the study
were two butternut squash types, 'Ponca' and 'Waltham' and
a calabash type, 'La Primera'. The parents, F1 and F2 generations
of each cross, 'Ponca' x 'La Primera' and 'Waltham' x 'La
Primera', were grown in separate replicated (randomized
complete block) experiments in the field, Lincoln, Nebraska
(1980). Trifluralin was incorporated into the soil at the
rate of 1 lb. a.i./acre (1.12 kilos a.i./ha) a day prior
to transplanting the squash seedlings.
'Ponca' and 'Waltham' showed high susceptibility to trifluralin
injury while 'La Primera' was slightly less susceptible
than these. The F1s of both crosses were highly susceptible.
The F2 segregation for both crosses suggested that the cultivars
possessed different genes for susceptibility to trifluralin
toxicity since a number of transgressive segregates for
high tolerance to trifluralin injury were observed.
We observed that injured plants had restricted root development
and a subsequent poor vegetative growth. Most of these eventually
died while a few that recovered did not fruit before frost.
The occurrence of resistant transgressive segregates indicated
that there is potential in these squashes to breed for resistance
to a family of herbicides, such as the dinitroanilines,
and this could possibly permit the use of these herbicides
for weed control to overcome some of our present control
problems.
Literature Cited
- Lange, A., D. May, B. Fisher and F. Ashton. 1968. Weed
control in cucurbits. Cal. Agr. 22: 8-9.
- Talbert, R. E. 1969. Evaluation of herbicides for weed
control in cucurbits. Weed Sci. Soc. Amer. (Abstr.) 45.
