Purslane

Both lantana and common purslane are weed pests in some crops. Common purslane root exudates inhibited soybean growth but showed stimulation in other bioassays reported in this paper. This may be a concentration and bioassay species dependent effect, since the effect of any toxin varies according to concentration and bloassay species (12). Lantana root exudates showed the strongest inhibitory effect on soybean growth of any of the species tested. Lantana is not found in soybean fields but is a weed pest in some areas in citrus orchards. Holm (13) included lantana, johnsongrass, and cogongrass in his list of the worst weed pests in the world. 

Based on the results from radish seeds, we also studied the influence of the rue extract on germination of purslane. Purslane is a major weed worldwide of 45 crops in 81 countries. The ploughable layer of the soil cropped with maize contains about 220,000 purslane seed per m2. Purslane fruit is a capsule with a pyxidium and a caliptra containing 50-70 black seeds (Holm etal.,1977). 

Procedure Purslane seeds were collected from crop fields near Naples. Five hundred seeds were sown in 10 Petri dishes (0 =90 mm), containing 5 layers of Whatman filter paper impregnated with 7 ml of water (control) or 7 ml rue infusion/chromatographic fractions or isolated compounds as per treatment. Thereafter, daily 3 ml water was added to each Petri plate. Germination conditions were 30 1°C with a continuous light of 25 4,E/m2/... 

Anatomical and ultiastructural aspects of in vitro germination of the purslane seeds may be studied using stereo and SEM microscopy (Figures 8 and 10). 

Procedure A dry quiescent purslane seed and the successive changes when it is moistened have been reported here. 

Experiment 1. Morphology of purslane seeds treated with me extract. 

Fig. 9 Time course of endosperm protrusion and germination of purslane seeds without rue infusion (control) and with rue infusion. Histograms represent the mean SD of percentage of dormant ( ), protruded endosperm (0) and germinated seeds .

Important steps for preparation of radish and purslane seeds for microscopy are listed below ... 

The effect of applied plant residues can be positively influenced by an increase of temperature. Mallek et al. (2007) established that dried and milled crop residues of onion (Allium cepa L.) or garlic (A. sativum L.) were able to reduce seed germination of barnyard grass (E. crus-galli (L.) R Beauv.), common purslane (Portulaca oleracea L.), london rocket (Sisymbrium irio L.) during their decomposition in soil, but only at the elevated (39°C) soil temperature. It can support combination of methods for weed control, in this case allelopathy with soil heating treatments (e.g., solarization). 

Portulaca grandiflora Hooker Song Ye Mo (Purslane) (whole plant) Portulal, betacyanin, betanin, betanidin.55 Treat throat swelling and pain, externally for bums, wounds and infections. 

Portulaca oleracea L. Ma Chi Xian (Purslane) (aerial part) Potassium salts, catecholamines, norepinephrine, dopamine, vitamin A, vitamin B, magnesium.33 49 Antibacterial, diuretic, causes vasoconstriction, stimulates uterine and intestinal smooth muscle contraction. 

Masabni et al (1996) identified a Ser264 to Thr (threonine) mutation in a resistant biotype of common purslane. This conferred a high level of resistance to atrazine and also to linuron, a substituted urea herbicide. This was the first report of a Ser264 to Thr substitution in higher plants selected under field conditions. Previously, this mutation had only been selected through tissue culture in tobacco and potato (Sigematsu et al, 1989 Smeda etal, 1993). 

---