Soil Chemical Analysis

Short protocols in molecular biology

Mineral Nutrition of Higher Plants, 2nd edition, H. Marschner. Academic Press, London (1995), 889, (ISBN 0-12-473543-6). Price: 29.95 Pound Sterling

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Food and Agricultural Organization of the United Nations.

The idea of eliminating the use of fertilizers which are sometimes environmentally unsafe is slowly becoming a reality because of the emergence of microorganisms that can serve the same purpose or even do better. Depletion of soil nutrients through leaching into the waterways and causing contamination are some of the negative effects of these chemical fertilizers that prompted the need for suitable alternatives. This brings us to the idea of using microbes that can be developed for use as biological fertilizers (biofertilizers). They are environmentally friendly as they are natural living organisms. They increase crop yield and production and, in addition, in developing countries, they are less expensive compared to chemical fertilizers. These biofertilizers are typically called plant growth-promoting bacteria (PGPB). In addition to PGPB, some fungi have also been demonstrated to promote plant growth. Apart from improving crop yields, some biofertilizers also control various plant pathogens. The objective of worldwide sustainable agriculture is much more likely to be achieved through the widespread use of biofertilizers rather than chemically synthesized fertilizers. However, to realize this objective it is essential that the many mechanisms employed by PGPB first be thoroughly understood thereby allowing workers to fully harness the potentials of these microbes. The present state of our knowledge regarding the fundamental mechanisms employed by PGPB is discussed herein.

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Mechanisms of action of plant growth promoting bacteria

Nashwa S.M.A., Abo-Elyousr K.A.M. (2012): Evaluation of various plant extracts against the early blight disease of tomato plants under greenhouse and field conditions. Plant Protect. Sci., 48: 74–79. The antimicrobial activity of six plant extracts from ocimum basilicum (Sweat Basil) , Azadirachta indica (Neem), Eucalyptus chamadulonsis (Eucalyptus), Datura stramonium (Jimsonweed), Nerium oleander (Oleander), and Allium sativum (Garlic) was tested for controlling Alternaria solani in vitro and in vivo . In in vitro study the leaf extracts of D. stramonium, A. indica , and A. sativum at 5% concentration caused the highest reduction of mycelial growth of A. solani (44.4, 43.3 and 42.2%, respectively), while o. basilicum at 1% and 5% concentra tion and N. oleander at 5% concentration caused the lowest inhibition of mycelial growth of the pathogen. In greenhouse experiments the highest reduction of disease severity was achieved by the extracts of A. sativum at 5% concentration and D. stramonium at 1% and 5% concentration. The greatest reduction of disease severity was achieved by A. sativum at 5% concentration and the smallest reduction was obtained when tomato plants were treated with o. basilicum at 1% and 5% concentration (46.1 and 45.2 %, respectively). D. stramonium and A. sativum at 5% concentration increased the fruit yield by 76.2% and 66.7% compared to the infected control. All treatments with plant extracts significantly reduced the early blight disease as well as increased the yield of tomato compared to the infected control under field conditions.

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Evaluation of Various Plant Extracts against the Early Blight Disease of Tomato Plants under Greenhouse and Field Conditions

Management of the root-knot nematode Meloidogyne incognita on tomato with combinations of different biocontrol organisms

Integrated control of cotton root rot disease by mixing fungal biocontrol agents and resistance inducers

Effectiveness of plant extracts on suppression of damping-off and wilt diseases of lupine (Lupinus termis Forsik)

Nine isolates of Trichoderma were collected from Assiut Governorate,Egypt, as leaf surface and endophytic fungi associated with onion ﬂorastalks. Four isolates were identiﬁed as Trichoderma harzianum, while ﬁveisolates were belonging to Trichoderma longibrachiatum. The antagonisticactivity of these isolates against onion purple blotch pathogen Alternariaporri was studied in vitro using dual culture assay. All tested Trichodermaisolates showed mycoparasitic activity and competitive capability againstthe mycelial growth of A. porri. Mycoparastic activity of Trichoderma wasmanifested morphologically by the overgrowth upon the mycelial growthof the pathogen and microscopically by production of coiling hyphaearound pathogen hyphae. Isolates of T. harzianum exhibited high abilityto compete on potato dextrose agar (PDA) medium causing the maximumrate of pathogen inhibition (73.12%), while isolates of T. longibrachiatumshowed inhibition rate equalling 70.3%. Chitinase activity of Trichodermawas assayed, and T. harzianum Th-3013 showed the maximum value con-tributing 2.69 U/min. Application of T. harzianum Th-3013 to control pur-ple blotch disease in vivo under greenhouse conditions caused diseasereduction up to 52.3 and 79.9% before and after 48 h of pathogen inocu-lation, respectively, while the fungicide Ridomil Gold Plus caused diseasereduction comprising 56.5 and 71.7%, respectively. This study proved thatT. harzianum Th-3013 as a biocontrol agent showed signiﬁcant reductionin onion purple blotch disease compared with the tested fungicide.IntroductionPurple blotch disease, caused by Alternaria porri (Ellis)Cif., is one of the most serious diseases that wide-spread in many parts of the world, restricted to Alliumspp. and more prevalent in warm and humid environ-ments (Cramer 2000; Suheri and Price 2000). Purpleblotch disease caused signiﬁcant reduction in bulband seed yield of the onion crop (Gupta and Pathak1988). The disease is more severe on seed crop ascompared to bulb crop causing sometimes 100% loos-ing of the seed production (Singh et al. 1992;Schwartz 2004). Although chemical control of onionblotch had been practised and its success depends lar-gely on high frequency of spraying, but today, thereare strict regulations on chemical fungicide use due tocarcinogenic effects, residual toxicity problems, envi-ronmental pollution and development of fungicide-resistant strains (Benitez et al. 2004; Rial-Otero et al.2005). Therefore, there are a large number of studiesthat have been devoted to apply a biological control asnature-friendly alternative method (Siameto et al.2010; Soria et al. 2012). The potential of Trichodermaspecies as biocontrol agents of plant diseases was ﬁrstrecognized in the early 1930s (Weindling 1932), andsince then, there have been extensive efforts in thecommercial production of them for disease control ina number of crops (Harman 1996; Gardener and Frav-el 2002). Recently, several investigation proved thatTrichoderma have been used to control many foliar

Kamal A. M. Abo-Elyousr

Papers

Evaluation of Various Plant Extracts against the Early Blight Disease of Tomato Plants under Greenhouse and Field Conditions

Management of the root-knot nematode Meloidogyne incognita on tomato with combinations of different biocontrol organisms

Integrated control of cotton root rot disease by mixing fungal biocontrol agents and resistance inducers

Effectiveness of plant extracts on suppression of damping-off and wilt diseases of lupine (Lupinus termis Forsik)

Isolation of Trichoderma and Evaluation of their Antagonistic Potential against Alternaria porri