A mong the many activities of animals, few seem more outlandish than the leaf-cutting and fungus-growing habits of attine ants of the New World tropics. In a typical rainforest, endless processions of workers transport leaf forage on cleared highways across the forest f loor, each worker balancing a leaf fragment like an oversized green umbrella (Fig. 1). The ants do not eat the leaves, but the...

We have compared the time course of leaf senescence in pea (Pisum sativum L. cv Messire) plants subjected to a mild water deficit to that of monocarpic senescence in leaves of three different ages in well-watered plants and to that of plants in which leaf senescence was delayed by flower excision. The mild water deficit (with photosynthesis rate maintained at appreciable levels) sped up senesce...

The concentrations of both essential nutrients and chemically similar toxic analogues accumulated in cereal grains have a major impact on the nutritional quality and safety of crops. Naturally occurring genetic diversity can be exploited for the breeding of improved varieties through introgression lines (ILs). In this study, multi-element analysis was conducted on vegetative leaves, senesced fl...

We show how the flag f-vector of a polytope changes when cutting off any face, generalizing work of Lee for simple polytopes. The result is in terms of explicit linear operators on cd-polynomials. Also, we obtain the change in the flag f-vector when contracting any face of the polytope.

Ozone-sensitive and -tolerant individuals of cutleaf coneflower (Rudbeckia laciniata L.) were compared for their gas exchange characteristics and total non-structural carbohydrates at Purchase Knob, a high elevation site in Great Smoky Mountains National Park, USA. Photosynthesis and stomatal conductance decreased with increased foliar stipple. Sensitive plants had lower photosynthetic rates fo...

BACKGROUND AND AIMS The amount of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) synthesized in a leaf is closely correlated with N influx into the leaf throughout its lifetime. Rubisco synthesis and N influx are most active in the young leaf during expansion, but are very limited in the senescent leaf. However, it is not established whether Rubisco synthesis can be obse...

in order to investigate the effect of organic and chemical fertilizers on growth characteristics of marjoram, a factorial experiment was conducted based on randomized complete block design with three replications at the agricultural research station, ferdowsi university of mashhad during 2012-2013 growing season. treatments were comprised of four urea levels (0, 21.7, 108.7 and 195.7 kg.ha-1) a...

The aim of this study was to determine nature and extent of variability parameters and their utilization in barley breeding programme. A total of 45 F1s along with their parents and F2 populations were evaluated in a randomized block design with 3 replications during Rabi (winter season) 2014. The various traits measured were days to 50% flowering, days to maturity, plant height, flag leaf area...

in order to evaluate the effects of nitrogen fertilizer on yield, yield components and dry matter remobilization of different rice genotypes, a field experiment was carried out at the farm of ramin agricultural and natural resources university (ahwaz/iran) during 2007. experiment was arranged in a split plot based on randomized complete block design with three replications. four nitrogen fertil...

Rates of photosynthesis, dark respiration, and leaf enlargement were studied in soil-grown corn (Zea mays), soybean (Glycine max), and sunflower (Helianthus annuus) plants at various leaf water potentials. As leaf water potentials decreased, leaf enlargement was inhibited earlier and more severely than photosynthesis or respiration. Except for low rates of enlargement, inhibition of leaf enlarg...