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Volume 4 Number 12 December 2018

Biochemical Resistance Mechanism Study of Jatropha curcas (Euphorbiaceae) Against Lasiodiplodia theobramae, a Leaf Blight and Necrosis Agent


Authors: Sama Hemayoro ; Sombié Pierre Alexandre Eric Djifaby ; Hilou Adama ; Bonzi Schemaeza ; Irénée Somda
Pages: 176-185
DOI: doi.org/10.32861/jac.412.176.185
Abstract
This study was initiated in order to understand the biochemical mechanisms involved in the resistance of J. curcas to Lasiodiplodia theobromae. Artificial inoculations were done on young seedlings leaves of 8 J. curcas local accessions from Burkina Faso including 4 resistant and 4 susceptible. Two extractions were made for the evaluation of each biochemical parameter: one on the 1st day before and the second on the 7th day after inoculation. The study revealed that the response of J curcas to L. threobromae infection is depending to the resistance or the susceptibility of accessions. It showed an increase in the content of biomolecules synthesis such as phenolic, flavonoids, proteins, photosynthetic pigments, salicylic acid and also an increase of catalase and trypsin inhibition activities. In susceptible accessions, the study revealed a decrease in the photosynthetic pigments and an increase in MDA content comparatively to resistant accessions. The ACP performed on the basis of the evaluated biochemical parameters showed that the axis F1 allows the separation of the resistant and the susceptible accessions, and indicated that the resistance of accessions result in the activation of biomolecules synthesis such as phenolic, flavonoids, proteins, photosynthetic pigments, salicylic acid and stimulation of catalase and trypsin inhibition activities. The F2 axis is associated with sugars content and, chymotrypsin inhibition and SOD activities. In susceptible accessions, an increase in MDA content and SOD activity were observed. This study represents an important step in combating leaf fungal diseases by opting to the green technology and by breeding for genotypes with inducing natural defense compounds.

Assessment of Factors Limiting Production of Citrus among Smallholder Farmers in Benue State, Nigeria


Authors: Attah A. J. ; Mbah E. N. ; Okeke M. N.
Pages: 170-175
DOI: doi.org/10.32861/jac.412.170.175
Abstract
The study assessed factors limiting production of citrus among smallholder farmers in Benue state, Nigeria. Primary data were collected from 120 respondents using structured questionnaire. Data were analyzed using frequency, percentage, mean score and factor analysis. Results revealed that 80% males and 20% females were involved in citrus production in the study area, 95% were married with 74.17% having citrus farm size of 1-3 hectares. Site selection (93.3%), variety and rootstock selection (91.7%), irrigation (91.7%), disease control (91.7%), pest management (88.3%), fertilizer application (86.7%), wind breaks (83.3%), grafting/budding (81.7%) were major citrus management practices used by the respondents. Respondents’ activities in citrus production were constrained by infrastructural, fund-related and institutional factors. The study concluded that more males than females were involved in citrus production. It is recommended that research and extension agencies should target appropriate technologies that will improve productivity of citrus and increase income of smallholder farmers for economic empowerment.

Effects of Inhibition of Starch Branching Enzyme on in situ Degradation of Endosperm Starch During Rice Seedling Growth


Authors: Juan Wang ; Ting Pan ; Cunxu Wei
Pages: 164-169
DOI: doi.org/10.32861/jac.412.164.169
Abstract
Cereal endosperm with inhibition of starch branching enzyme (SBE) increases resistant starch content and has health benefit. For plants, endosperm starch is degraded to provide energy for seedling growth. However, whether the inhibition of SBE influences in situ degradation of starch during seedling growth is seldom reported. In this study, a normal japonica rice cultivar Wu-xiang 9915 (WX) and its derived transgenic rice line (WTR) with inhibition of SBE were cultivated in the dark only in deionized H2O. The plant growth and starch property changes were investigated during seedling development. Compared with WX, WTR showed a significantly slow plant growth. The slow degradation of starch in seed restrained the plant growth. For WX, the amylopectin and amylose were simultaneously degraded, leading to that the endosperm residual starches had similar crystalline and short-range ordered structure during seedling development. However, for WTR, the amylopectin had higher resistance to in situ degradation than amylose, and endosperm residual starches changed from CA- to CB-type and its ordered structure increased during seedling development.

Allelopathic Effect of Aqueous Extracts of Parthenium (Parthenium Hysterophorus L.) Parts on Seed Germination and Seedling Growth of Maize (Zea Mays L.)


Authors: Tesfay Amare
Pages: 157-163
DOI: doi.org/10.32861/jac.412.157.163
Abstract
Twice repeated experiment was carried out under laboratory conditions to investigate the allelopathic effects of aqueous extracts of Parthenium hysterophorus L. shoot (stem + branch) and leaf, at 0, 5, 10 and 15 g L-1 (w/v) concentrations on maize (Zea mays L.) seed germination, seedling growth (shoot and root length) and biomass production. The treatments were laid out in completely randomized design with the factorial arrangement in four replications. Result indicated that the highest germination percentage (98.75%) was recorded from control whereas the lowest (43.75 %) was from stem extract at15 g L-1 concentration level. Similar trend was also observed by leaf extract. Root and shoot length of maize crop was reduced by 91.4 % and 70.8% by 85.6 and 35.8% leaf extracts and stem extracts respectively hence the roots were more sensitive to allelopathic effect than shoot. Extract of both leaf and stem at 15 g L-1 strongly reduced fresh and dry biomass of the maize seedling. The highest (100,100 %) tolerance index was recorded from control whereas, the lowest (8.62, 14.74%) was recorded from leaf and stem extract at 15 g L-1 concentration level respectively. Leaf aqueous extract showed more phytotoxic effect (91.37 %) than stem extracts (85.25) at 15 g L-1 whereas was the minimum recorded in control (0.0%).  15 g L-1 minimum value of vigor index (200, 539.2) and higher inhibition potentials (62.5 and 55.78%) were recorded from leaf and stem respectively. therefore allelopathic effect by the parthenium extracts is concentration-dependent manner. Leaf extract had shown highest inhibition potential followed by the stem.