Interception of photosynthetically active radiation (PAR) was evaluated relative to greenness and normalized difference [MSS (7 5)/(7 + 5)] for five planting dates of wheat for 1978-79 and 1979-80 at Phoenix, Arizona. Intercepted PAR was calculated from leaf area index and stage of growth. Linear relationships were found with greenness and normalized difference with separate relationships descr...

this research aimed to evaluate the effect of planting seasons (autumn and spring) on 10 accessions of two species of astragalus effusus and astragalus brachyodontus in the field condition (homand absard station, damavand). after preparing the seedbed, the plant species were planted on two lines in 2 m, where the spacing between the lines of each accession was 0.5 m, and the spacing between the...

Onion thrips (Thrips tabaci Lindeman (Thysanoptera: Thripidae)) can be a pest in organic onion production on Prince Edward Island. This study was to examine the effect of planting time and variety on infestation levels and damage by onion thrips on cabbage (Brassicae oleracea capitala (L.)). A field site was planted with 2 main and 8 lesser varieties of cabbage over 4 planting dates. Some varie...

Environ.Entomol.21(2):264-268(1992) ABSTRACT Soybean, Glycine max (L.) Merr., resistance to insects has been shown to vary with planting date and leaf age. This study determined effects soybean genotype, planting date, and leaf age had on feeding behavior of com earworm, Helicoverpa zea (Boddie). Soybean genotypes 'Cobb' (susceptible) and 'GatIR81-296' (resistant) were planted early (29May) and...

The timing of herbivory can be an important factor in the strength and direction of plant response to herbivore damage. To determine the effect of vole herbivory timing within a growing season on tallgrass prairie forbs, we used individual plant enclosures to limit vole access to three species, Desmanthus illinoensis, Echinacea purpurea, and Heliopsis helianthoides, in an experimental restorati...

The effect of crop sequence on parasitism of second-stage juveniles (J2) of Heterodera glycines by Hirsutella rhossiliensis was investigated. Data were collected from plots of a long-term crop rotation experiment established in 1982. Crop sequences included (i) continuous monoculture of corn and soybean; (ii) annual rotation of the two crops; and (iii) 1, 2, 3, 4, or 5 years of each crop follow...

BACKGROUND: The ability of a plant to resist or tolerate pests is grounded partially in favorable physical, chemical and biological properties of soil. OBJECTIVES: Investigate the influence of nutrient sources on Podagrica uniforma and Nisota dilecta infestation, population dynamics and performances of okra. METHODS: </stro...

The population density of Hoplolaimus magnistylus, a lance nematode, in cotton was determined at planting, mid-season, and harvest during the 1995 and 1996 growing seasons for a Poinsett County, Arkansas field. Nematode populations increased from planting to harvest in 1995 but declined in 1996. Application of aldicarb at planting at rates of 0.59 or 0.84 kg a.i./ha did not influence either nem...

Prior to the 2000 planting season, some industry obsemers predicted acreage of genetically modified crops would decline dramatically. However, actual 2000 plantings presented a puzzle. Farmers reduced their acreage of genetically modified corn, but concurrently increased their acreage of genetically modified soybeans. We demonstrate that it may be theoretically optimal for risk-averse farmers t...

Early fertilizer nitrogen (N) application on cover crops or their residues during the off-season is a practice adopted in Brazil subtropical conditions under no-tillage corn (Zea mays L.) systems. However, the effect of early N application on yield, plant N content, and N recovery efficiency (NRE) for corn is not yet well documented. Five fertilizer N timings in an oat-corn system were evaluate...