SEEDLING GROWTH TOLERANCE OF CUCURBITS CROPS TO HERBICIDES STOMP AND ACETOCHLOR
Summary. Several species from the Cucurbitaceae family including muskmelon, watermelon, cucumber, pumpkin, and squash were used to evaluate their tolerance in a laboratory test to two herbicides (Stomp and Acetochlor) widely used in crop cultivation. The effects of concentration and site of herbicide action on the length of primary roots and hypocotyls as well as seedling fresh weight were studied. The results showed that the cultivars differed greatly in their sensitivity to the herbicide action. The difference in the growth responses was not only species-, but also cultivar-specific. In addition, there was a difference in the herbicide acting site on plants which depended on the kind of cucurbits crops. Based on the tolerance to the action of both herbicides the studied species can be classified as follows: watermelon, squash, pumpkin, muskmelon, cucumber. The tolerance differences of the studied cucurbits crops can be used in cultivation practice.
Effectiveness of the Primextra Gold in controlling weeds of Cucumber ( Cucumis Sativus .)
: The efficacy of Primextra Gold herbicide in controlling weeds in cucumber was evaluated in this research. The experiment was laid out in a randomized complete block design with four replications. Seven weed control treatments – 0.0, 0.25, 0.5, 0.75, 1.0, 1.25 and 1.5 kg a.i/pot – were applied pre-emergent for this study. The dry weight, height of plant, number of green leaves, weed control efficiency, weed persistence index, crop phytotoxicity rating, weed destruction rating, weed count (total number of weeds), weed flora and classification were used to determine the herbicide efficacy and crop safety. Results show that the effects of the treatments were mostly significant; all the treatments caused over 50% injury to the cucumber at all stages except at 7 Days After Treatment. At the end of the experiment, results show that the treatments were highly toxic as they caused up to 100% injury to the cucumber preventing height, dry weight or leaf number measurements to be taken except in pots which received 0.25kg a.i/pot of the herbicide and the control. Weed destruction ratings was over 50% for all of the treatments and at all stages, except for 0.25kg a.i/pot at 21 and 28 DAT. Weed density and dry weight were significantly reduced by the treatments. WCE% recorded was over 50% while WPI was zero (0) for all treatments except 0.25kg a.i/pot. Common weeds observed include Oldelandria corymbosa and Digitario sp.
New Trends in Fungal Biooxidation
Biooxidations using isolated biocatalysts for the oxidative conversion of organic compounds and materials are becoming more and more important in the industrial sector. Research in this direction is part of the rapidly developing field of White Biotechnology and is carried out not least against the background of sustainable development and the need to replace environmentally risky technologies by eco-friendly processes. Whereas whole cells are already widely used as oxidative biocatalysts, the application of isolated enzymes is still limited to a few examples. One reason for that is the cost-intensive production and laborious purification of enzymes which are mostly intracellular and sometimes membrane-bound proteins with low stability and complex co-factor requirements. The use of secreted oxidoreductases offers several advantages: they are easier to separate and purify, need only cheap co-substrates such as dioxygen or peroxides and are far more stable than intracellular enzymes. Filamentous fungi secrete a broad spectrum of oxidative biocatalysts which are involved, amongst others, in the degradation of recalcitrant biopolymers, the synthesis of melanins as well as the detoxification of plant ingredients, microbial metabolites and organopollutants. We focus here on novel secreted enzymes - peroxygenases and DyP-type peroxidases - with remarkable catalytic properties. Furthermore selected features of “classic” fungal oxidoreductases, such as laccase, tyrosinase and chloroperoxidase, are discussed against the background of innovative recent developments in the field of enzyme application.