Allelopathic potential of two sorghum cultivars on weeds, mung bean and symbiotic nitrogen fixation and possible rapid identification of allelopathic potential by PCR technique

العناوين الأخرى

الجهد الالبلوباثي لصنفين من الذرة البيضاء في الأدغال و كحصول الماش و تثبيت النيتوجين تكافليا و محاولة تشخيص الجهد الالبلوباثس باستعمال تقانة التفاعل التضاعفي لسلسة الدنا

مقدم أطروحة جامعية

al-Khatib, Tamarah Adnan Ali

مشرف أطروحة جامعية

Hadwan, Hamid A.
al-Sadawi, Ibrahim Shaban

أعضاء اللجنة

Yasin, Kazim H.
Shatti, Risan K.
Yunus, Muayyad A.
Atiyyah, Hatim Jabbar
Jasim, Ali H.

الجامعة

جامعة بغداد

الكلية

كلية العلوم

القسم الأكاديمي

قسم علوم الحياة

دولة الجامعة

العراق

الدرجة العلمية

دكتوراه

تاريخ الدرجة العلمية

2014

الملخص الإنجليزي

Two field experiments and several greenhouse and laboratory experiments were conducted during the course of study to test the allelopathic potential of two sorghum (Sorghum bicolor L.) cultivars on companion weeds and weeds grown in mung bean (Vigna radiate L.) crop and to determine the chemical and genetical bases of allelopathic traits in the test cultivars.

The first field experiment was conducted during 2011 at Experimental Station of Field Crops Department, Abu-Ghraib, State Board of Agricultural Researches in Baghdad, Iraq to test whether the variation in weed population and biomass between the stands of Enqath and Rabeh sorghum cultivars, which was observed in the field, was due to differences in their allelopathic potential.

Results revealed that the Enqath cultivar significantly suppressed density and dry weight biomass of companion weeds over the Rabeh cultivar by 34 and 29% after 35 DAS, and 22 and 24% after 65 DAS.

A staircase experiment indicated that root exudates of the Enqath cultivar suppressed weeds more than Rabeh giving additional evidence for the superiority of the Enqath cultivar in its allelopathic weed suppression.

Chemical analysis indicated the presence of sorgoleone compound in root exudates of both cultivars with a significantly higher amount in the Enqath cultivar (8 mg/g d.

w.) compared to cultivar Rabeh (6.8 mg/g d.

w.).

Phenolics were also present in sizeable amount .These compounds appeared to be higher in Enqath (0.22 mg/g) than in Rabeh (0.14 mg/g) giving additional evidence for the higher allelopathic potential of Enqath.

Chemical analysis on these phenolics by HPLC indicated the presence of several allelochemicals, viz, protocatechuic, hydroxybenzoic, vanillic, syringic, pcoumaric, ferulic and sinapic acids.

II The second field experiment was conducted in the field of Department of Biology, College of Science; Baghdad University to test the effects of residues of tested sorghum cultivars on weeds grown in mung bean field and growth and productivity of mung bean crop.

The results indicated that weed density reduced by 36 and 44% of control by incorporating Enqath residue at rates of 500 and 1000 g per m2 at 30 days after sowing (DAS), respectively.

While the reductions were 22 and 25% of control by incorporating of aforementioned residue rates of Rabeh cultivar.

The reduction in weed density remained higher by Enqath than by Rabeh residues at 60 DAS.

Aboveground biomass of weeds was also reduced significantly by incorporation of residues of both sorghum cultivars and the reduction increased with the increased residue rate; however, Enqath was the most weed biomass suppressing cultivar compared to Rabeh cultivar.

Chemical analyses of residues indicated that total phenolics were found to be higher in Enqath plants than in Rabeh plants suggesting the superiority of allelopathic potential of Enqath cultivar over Rabeh cultivar against weeds.

Incorporation of sorghum residues significantly increased yield and number of pods per plant and weight of 100 - seed over control.

Maximum yield was obtained in plots received Enqath residue at 500 and 1000 g per m2 residues followed by plots amended with Rabeh residue at the aforementioned rates.

Results of biological nitrogen fixation experiment revealed that inoculation of seeds of mung bean with RJ1 or R6 isolate and grown in soil with sorghum residues recorded maximum number of root nodules per plant, dry weight of nodules, total nitrogen in plant and leghemoglobin content of nodules compared to RJ1 or R6 isolate inoculated seeds grown in soil without residues.

Similarly, Isolates RJ1 and R6 in combination with peat moss significantly improved the aforementioned parameters compared with the treatments of RJ1 and R6 alone.

However, sorghum residues were more efficient than peat moss.

III Results of using RAPD technique on the sorghum genomic DNA revealed that all the 10 primers used in this study scored different amplification monomorphic and polymorphic bands in the tested genotypes with the exception of 3 RAPD primers which generated a unique amplification bands, one of them (1250bp) scored by OPN 16 primer, present in high allelopathic sorghum genotypes and absent in the low allelopathic ones (Rabeh).

Further work is recommended to analyze the sequence of this band to find out whether it is related to allelopathic trait or not.

If the gene(s) responsible for allelopathic effects are identified, allelopathic traits can be incorporated into improved cultivars through plant breeding programs.

التخصصات الرئيسية

النبات

الموضوعات

• الإدارة
• المحاصيل
• مبيدات الأعشاب
• الرقابة
• المضادات الحيوية
• الذرة الرفيعة(جنس)
• التضاد البيوكيميائي

عدد الصفحات

119

قائمة المحتويات

• APA
• MLA
• AMA

لغة النص

الإنجليزية

نوع البيانات

رسائل جامعية

رقم السجل

BIM-599178