Photosynthate translocation in single leaflets of healthy and curly top virus-infected tomatoes was investigated using (14)C as a marker. The amount of radioactivity found in plant parts not exposed to (14)CO(2) was substantially lower in diseased than in healthy plants. The time lag for the appearance of (14)C in the petiole was considerably longer in the infected plants than in the healthy. T...

Evaluation of crop N status will assist optimal N management of intensive vegetable production. Simple procedures for monitoring crop N status such as petiole sap [NO 3--N], leaf N content and soil solution [NO 3-] were evaluated with indeterminate tomato and muskmelon. Their sensitivity to assess crop N status throughout each crop was evaluated using linear regression analysis against nitrogen...

Virus-induced gene silencing (VIGS) was used as a tool for functional analysis of cell wall-associated genes that have been suggested to be involved in leaf abscission. Tobacco rattle virus is an effective vector for VIGS in tomato (Lycopersicon esculentum). Silencing was more efficient when the plants were grown at 22 degrees C than when they were grown at 20 degrees C or 25 degrees C. The pho...

The physiological role of phenylacetic acid (PAA) as an endogenous regulator of cotyledon abscission was examined using cotton (Gossypium hirsutum L. cv LG 102) seedlings. Application of 100 micromolar or more PAA to leafless cotyledon abscission-zone explants resulted in the retardation of petiole abscission and a decrease in the rise of ethylene evolution that normally accompanies aging of th...

Water-soluble glycopeptides isolated from cultures of Ceratocystis ulmi have been reported to be toxins involved in Dutch elm disease. The influence of the glycopeptides on the water relations of Ulmus americana seedlings was tested by placing cut stems in glycopeptide preparations. After 4 hours in 200 micrograms per milliliter toxin the stem conductance of the seedlings was reduced by 79% and...

The present work describes a novel neoformation process of Brassica juncea (L.) Czern. seedlings from transverse thin cell layers in the presence of CdCl2. In order to investigate the regeneration ability of this crop, the effect of CdCl2 on shoot regeneration (frequency of regeneration and bud number per tTCL) was examined. The tTCL explants were excised from cotyledon, petiole and hypocotyl o...

There are two optima for maximizing hydraulic conductance per vasculature volume in plants. Murray's law (ML) predicts the optimal conduit taper for a fixed change in conduit number across branch ranks. The opposite, the Yarrum optimum (YO), predicts the optimal change in conduit number for a fixed taper. We derived the solution for YO and then evaluated compliance with both optima within the x...

An efficient protocol for callus induction and somatic embryogenesis of Cyclamen premium Mill. Was developed. In this study we investigate difference between response of two explants type leaf and petiole and two medium salt concentrations MS and 1⁄2 MS on callus percentage and somatic embryo number. Media was non-significant on callus production but leaf explants was better than petiole and in...