in order to determine the critical period of weed control (cpwc) in corn (zea mays l.), an experiment was carried out in a randomized complete blocks design with 14 treatments and three replications during 2013 growing season in the nahavand climatic conditions. two series of the treatments including weed-free and weed-infested were applied in the regular time distances of 10, 20, 30, 40, 50 an...

Hybridization and introgression between crops and wild relatives may have important evolutionary and ecological consequences such as gene swamping or increased invasiveness. In the present study, we investigated hybridization under field conditions between crop lettuce (Lactuca sativa) and its wild relative prickly lettuce (L. serriola), two cross-compatible, predominantly autogamous and insect...

Root hairs, which arise from root epidermal cells, are tubular structures that increase the efficiency of water absorption and nutrient uptake. A low pH (pH 4) medium induced root hair formation in lettuce (Lactuca sativa L.) seedlings, and the decapitation of shoots inhibited root hair formation. The addition of shoot extract to the medium restored root hair formation in the decapitated lettuc...

Consumption rates, development times, and life table parameters of the beet armyworm, Spodoptera exigua (Hübner), were determined on Þve host plants: cabbage, Brassica oleracea capitata L; cotton, Gossypium hirsutum L.; bell pepper, Capsicum annuum L.; pigweed, Amaranthus retroflexus L.; and sunßower, Helianthus annuus L. Mean total leaf weight consumed by larvae was highest in cabbage (2.7 g) ...

Weedy Amaranthus species frequently cause economically significant reductions in crop yields. Accurate identification of Amaranthus species is important for efficient weed control, but Amaranthus species can interbreed, which might cause difficulty when identifying hybrid-derived specimens. To determine which of several economically important weedy Amaranthus species are most genetically simila...

Cadmium ions influence on the content of anthocyanins as non-plastid pigments and the activity of phenylalanine ammonia-lyase (EC 4.3.1.24) as primary enzyme of their biosynthesis in two lettuce varieties (Lactuca sativa L.) with different anthocyanin content was investigated. The increases in anthocyanin content and enzymatic activity of phenylalanine ammonia-lyase of both lettuce plant variet...

Phototransformation of phytochrome in lettuce seeds (Lactuca sativa L. var. Grand Rapids) was examined by testing germination responses of seeds irradiated at various temperatures. Temperature variations from 0 to 50 C had no influence on the germination of partially hydrated seeds (about 15% water content) irradiated with either red or far red light prior to imbibition. At -15 C far red light ...

Kochia (Kochia scoparia L.), Russian thistle (Salsolatragus L.), and prickly lettuce (Lactuca serriola L.) are economically important weeds infesting dryland wheat (Triticum aestivum L.) production systems in the western United States. Those weeds produce most of their seeds post-harvest. The objectives of this study were to determine the ability of an optical sensor, installed for on-the-go me...