Production of chitinolytic enzymes with Trichoderma longibrachiatum IMI 92027 in solid substrate fermentation

Thirty Trichoderma strains representing 15 species within the genus have been screened for extracellular production of chitinolytic enzymes in solid substrate fermentation (SSF). T.longibrachiatum IMI 92027 (=ATCC 36838) gave the highest yield (5.0 IU/g dry matter of substrate) after 3 days of fermentation on wheat bran-crude chitin (9:1 mixture) medium. The optimum moisture content (66.7%), chitin content (20%), initial pH of the medium (2-5) and time course (5 d) of SSF were determined for strain IMI 92027. No significant effect of different N and P additives was found on the chitinase yield in wheat bran-chitin mixture medium. Cellulase, xylanase, alpha-amylase and beta-xylosidase activities were also detected. The pH and temperature optima of chitinase complex of T.longibrachiatum IMI 92027 was found to be at 4.5 and 55 ℃, respectively. The enzyme totally lost its activity at 70 ℃ in 5 min in the absence of the substrate but retained about 15% of its initial activity even at 70 ℃ after incubation of 60 min in the presence of SSF solids (residual substrate and fungal mycelium). Purification of protein extract from the SSF material revealed high chitinolytic activities between pI 5.9.-4.8 where N-acetyl-β-D-hexosaminidase and chitinase peaks have been found in the same pI range. Chitinase peaks could be described at least at four pI values: pI 5.9; 5.6; 5.3 and 4.8 while at least four main N-acetyl-β-D-hexosaminidase peaks could be separated at pI 6.0 and 5.1 and at more basic isoelectric points of 7.2 and 8.0. Two chitinases with 43.5 kDa and 30 kDa were purified at acidic isoelectric point.

Effect of Cultivar, Irrigation and Nitrogen Fertilization on Chickpea (<i>Cicer arietinum</i>L.) Productivity

A 2-year field study was conducted in northern Greece to investigate the effect of nitrogen fertilization and irrigation on productivity of three Greek chickpea varieties (“Amorgos” “Serifos”, “Andros”). Chickpea, grown under irrigation regime (30 + 30 mm of water) and fertilized with 50 kg·N·ha-1 before planting and with 40 kg·N·ha-1 at blossom growth stage, produced more total dry biomass and seed yield as compared with that grown under non-irrigated conditions and fertilized with 50 kg·N·ha-1 before planting only. In particular, irrigation and nitrogen fertilization at blossom growth stage increased total dry weight of chickpea by 18.3% and 18.5%, respectively, as compared with that of non-irrigated and fertilized with N before planting. The corresponding increase of seed yield was 30.5% and 20%, respectively. The total dry biomass of “Amorgos” was 10% and 13% greater than that of “Serifos” and “Andros”, while its respective seed yield increase was 5% and 16%. Finally, the quantum yield of photosystem II of chickpea was not affected by irrigation or fertilization. These results indicated that nitrogen fertilization at blossom growth stage combined with irrigation increased seed yield of all chickpea varieties, whereas the same treatments did not have any effect on plant quantum yield of photosystem II.

Influence of Weather and Climate on Malaria Occurrence Based on Human-Biometeorological Methods in Ondo State, Nigeria

This study focuses on the influence of weather and climate on malaria occurrence based on human-biometeorological methods was carried out in Ondo State, Nigeria using meteorological and malaria dataset in the state for the period from 1998 to 2008. In addition, sea surface temperatures （SSTs） over equatorial Pacific Ocean were integrated in the analysis. The association between each of the meteorological-biometeorological parameters and clinical-reported malaria cases was examined by using Poisson distribution and log as link function between the two categories of dataset. The next step was the building of a model by using Poisson multiple regression models （GLMs） in order to know the weather variables that lead to statistically changes in clinical-reported malaria cases. The study revealed that an increase of I m.s1 of wind speed can lead to an increase of about 164% and 171% in the monthly occurrence of malaria at 95% confidence interval in derived savanna and humid forest zone respectively. Also, an increase of I ℃ in air temperature and sea surface temperature is associated with 53.4% and 29% increase in monthly malaria occurrence （CI： 95%） in derived savanna while an increase of 1 ℃ in air temperature and sea surface temperature is associated with 56.4% and 15.4% increase in monthly malaria occurrence at 95% confidence interval in humid forest zone of Ondo State

Effects of Varieties and Cooking Methods on Physical and Chemical Characteristics of Cooked Rice

To analyze the effect of different lowland rice varieties and different cooking methods on physical and chemical characteristics of cooked rice. A factorial randomized block design with two factors was used and each combination of the factors was repeated three times. The first factor was rice variety（Ciherang and Ciliwung） and the second factor was the cooking method（stovetop, boiling and steaming, and rice cooker）. Results showed that Ciherang and Ciliwung varieties were classified into slender grain rice type with yellowred color. The amylose content of Ciherang was classified as moderate, while the amylose content of Ciliwung classified as low. The most abundant amino acid contained in Ciherang and Ciliwung varieties was glutamic acid. Statistical analysis showed that cooking method had significant effects on texture, lightness, chroma, hue and moisture content of cooked rice. Rice cooked with liwet method had the lowest texture value, lowest lightness value, highest chroma value, and highest moisture content.

Selection of Trichoderma mutants with enhanced cellulase production and resistant to catabolite repression

Due to high cost and relatively low efficiency of cellulase enzymes used for the saccharification of pretreated lignocelluloses, the improvement of cellulase secreting microorganisms is of vital importance. Trichoderma reesei QM 6a, an excellent source of cellulase was selected in the late 1960’s. at Natick Laboratories by its performance on pure cellulose (Solka Floc, Avicel) . QM 6a is the wild parent strain of best existing hypercellulolytic mutants such as Rut C30, VTT-D-80133, L27, CL-847 and others. Utilization of cheaper carbon sources (e.g., pretreated wood or straw) both in enzyme production and in hydrolysis necessitates to investigate fungal species other than T.reesei. A screening program was initiated to test 150 wild-type Trichoderma strains in shake flask for cellulase production on SO 2-impregnated and steam pretreated spruce and willow, candidate substrates for bioalcohol program in Sweden. Filter paper activity (FPA) method was used to determine the overall cellulase activity. Strain TUB F-1505 was selected as promising candidate for mutagenesis. This wild strain was isolated from a tropical rain forest area near Manaus, Brazil. Isolate F-1505 was subjected to NTG-mutation to select catabolite (glucose, glycerol) resistant mutants. A Petri plate clearing assay using Walseth cellulose, glycerol or glucose and Triton X100 (colony size inhibitor) was applied for pre-screening of the colonies. Over 6000 colonies were evaluated. Best colonies were tested in shake flask fermentation on pretreated spruce and willow as carbon sources. Mutants producing higher levels of cellulase (FPA) were further mutated by either NTG or UV-light. At least 4 mutants were obtained and freeze-dried exhibiting equivalent or higher cellulase production as compared to Trichoderma reesei Rut C30.

Trichoderma spp. capable of growing at low temperatures with biocontrol potential

@Szakacs G$Technical University of Budapest, Department of Agricultural Chemical Technology, 1111 Budapest, Gellert ter 4, Hungar@Tavaszi A$Technical University of Budapest, Department of Agricultural Chemical Technology, 1111 Budapest, Gellert ter 4,

Production of chitinases with Trichoderma harzianum isolates using solid substrate fermentation

Over forty Trichoderma harzianum isolates have been screened in solid substrate fermentation (SSF) for chitinase production. Strains were isolated from Asian soil and tree bark samples. Identification was performed in Canada and Austria by classical and molecular taxonomical methods. Four SSF media were used for the screening. They contained wheat bran, crude chitin from crab shells (SIGMA) and different salt solutions for wetting of the substrate. In a five day fermentation at 30°C the best chitinase producers were T. harzianum TUB F-691, TUB F-693, TUB F-699, TUB F-700, TUB F-927, TUB F-947 and TUB F-972 isolates (TUB = Technical University of Budapest culture collection) . The best producers yielded between 3.5-5.5 International Unit/g dry matter (DM) chitinase. T. harzianum TUB F-947 was selected for further optimization. This strain was isolated from a soil of Thailand. The optimum moisture content (67%), optimal alternative substrate-carrier for SSF (wheat straw) and chitin content of the substrate (30%) were determined. Temperature and pH optima of chitinase produced by T. harzianum TUB F-947 were found to be at 50°C and 5.0, respectively. The enzyme complex was thermally not stable at 50 ℃. Medium optimization experiments to enhance the chitinase production using statistical methods also have been performed.

Biodiversity of Trichoderma spp. in TUB culture collection

Culture collection of the Technical University of Budapest (TUB) comprises app ro x. 2800 microorganisms with special emphasis on lignocellulose degrading fungi a nd actinomycetes. For isolation and screening programs, 460 soils are stored at +5 ℃. They were collected in 58 countries, including extreme environments. There are 860 Trichoderma strains in TUB collection, representing 45 count ries and 173 soils and/or tree barks as isolation sources. Trichoderma spp . selected from soils in the tundra region (Rocky Mountains, Colorado) grow at l ow temperatures such as 5-10 ℃. These strains practically do not grow at 30 ℃ . On the contrary, many Trichoderma strains were isolated from tropical or s ubtropical soils and decaying plant materials at 35-40 ℃ in Brazil, Peru, Cost a Rica, Guatemala, Hawaii, Tanzania, Thailand and Indonesia. Trichoderma str ains tolerating limited oxygen supply were selected from river muds and sediment s. Trichoderma spp. tolerating or partially degrading 2,4-dichlorophenol a nd 2,4,6-trichlorophenol in 20 mg/kg concentration were selected from polluted soils. As a part of an attempt to assess the global biodiversity of Trichoderma, researchers of Technical University of Vienna and Agriculture Canada, in collab oration with TUB collection, identified and characterized seven new assumed taxa of Trichoderma from Eurasia.

Effectiveness of Ringworm Cassia and Turmeric Plant Extracts on Growth Inhibition against Some Important Plant Pathogenic Fungi

Crude plant extracts of ringworm cassia, Cassia alata L. and turmeric, Curcuma longa L. were prepared by either hot water or organic solvents such as ethanol and ether. Various concentrations of the crude extract were then subjected to an in vitro test for their effectiveness on mycelia growth inhibition against some important plant pathogenic fungi such as Alternaria alternata, Colletotrichum gloeosporioides, Fusarium oxysporum fsp. lycopersici, Sclerotium rolfsii, Phytophthora infestans and Pythium sp. in comparison to commercial fungicides such as copper oxychloride and mancozeb. Reduction of the fungal growth was significantly obtained with C. longa extracts and the best median effective inhibitory concentration (IC50) value of 6.07, 6.50 and 7.13 mg/ml was from the ethanol extract for S. rolfsii, C. gloeosporioides and F. oxysporum fsp. lycopersici respectively. While all extracts from C. alata were almost the least effective against these fungi. The efficacy of C. longa extracts therefore, provided an alternative regime for the control of the fungal diseases and a promising appreciable choice for a replacement of chemical fungicides.

Enzymes of Trichoderma and other origin in biopreparation of cotton

Preparation and bleaching are among the most energy and chemical intensive steps of the traditional cotton finishing. About 75% of the organic pollutants arising from textile finishing are derived from the preparation of cotton goods. Biopreparation may be a valuable and environmentally friendly alternative to harsh alkaline chemicals for preparing of cotton. Different enzymes i.e. cellulases, pectinases, lipases and proteases have been tested for biopreparation. Many papers have been published how enzymes effect on the properties of cotton fabrics in respect to their effectiveness to replace alkaline scouring and how enzymes modify the various cell wall components of cotton fibers. However, very few data have been reported on bleachability and dyeing behavior of the bioscoured fabrics. In this work an acidic cellulase (Celluclast 1.5 L, Trichoderma reesei origin), an acidic pectinase-hemicellulase (Viscozyme 120 L , Aspergillus aculeatus) and a cellulase-free xylanase (Pulpzyme HC, Bacillus sp.) enzymes were used for bioscouring of greige cotton fabric. Selected properties of the pretreated samples, which are important for effective dyeing, are characterized in detail. Effect of hydrogen peroxide bleaching, applied subsequent to the biopretreatment on the bleachability and dyeing properties of the samples is also elucidated. A reactive dye was used at four different concentrations to compare the dyeing behavior of biopretreated as well as biopretreated and subsequently bleached cotton fabrics with that of the alkaline scoured as well as alkaline scoured and bleached fabrics, respectively. Color evenness and uniformity, and wash fastness properties of the dyed samples are also determined [1]..

Influence of Heating Time of Shea Nuts (vitellariaparadoxa) on Some Chemical Properties of Shea Butter

The experiment was conducted in the laboratories of the Departments of Chemistry and Animal Health and Production Technology, Adamawa State University, Mubi, Nigeria. The experiment was replicated three times in a Randomized Complete Block Design (RCBD) and consisted of six heating time 30, 60 and 120 minutes boiling, 30, 60 and 120 minutes roasting and one control. Data were collected on acid value, free fatty acid, iodine value, peroxide value, saponification value and unsaponifiable matter. The data collected were analyzed statistically using Generalized Linear Model (GLM) procedure of statistical analysis system (SAS). The means that were significantly different were separated using Least Significant Difference (LSD). The results showed that there were highly significant differences (P ≤ 0.01) among the treatments. The highest Acid Value (AV) of 3.53 and 3.64 were recorded by heating time at 120 minutes of boiling and 120 minutes of roasting. Heating time at 30 minutes of boiling, 30 minutes roasting, 60 minutes boiling and 60 minutes roasting recorded lower Free Fatty Acid (FFA) values of 1.52, 1.55, 1.57 and 1.58, respectively. Heating time at 60 minutes of roasting and 60 minutes of boiling recorded the highest Iodine value (IV) of 43.80 and 43.53, respectively. Based on the results of this study, it can be concluded that heating time of 30 or 60 minutes by boiling or roasting are better than longer heating times for Shea butter extraction.

Potential Impacts of Climate Change on Food Security

In view of the fact that climate-related disasters are already taking a heavy toll, causing massive damage to crops and infrastructure and forcing some people to flee their homes, however, the potential impacts of climate change are likely to trigger adaptive responses that influence environmental and socio-economic drivers of food system performance in positive as well as negative ways. This paper was conducted through the collection of some research materials with the projected balance of these various climate impacts on food system performance and food security outcomes at the local and global levels. More so that, food security is likely to be affected by climate change in several ways： food security depends not only on the direct impact of climate change on food production but also on its indirect impact on human nutrition and health, economic growth, trade flows and food aid policy. The paper further examined the effectiveness of managing new risks and uncertainty, improving the quality of information and its use, monitoring weather and improving scientific understanding of climate change, promoting insurance schemes, maintaining biodiversity and access to fund as some of the crucial measures for adaptation. The large amount of resources that would be necessary to avoid the worst case scenario suggests the necessity of continued support from the international community to improve food security at the local and global levels as a whole.

Use of Sunflower Cake in the Diet of ISA Brown Pullets

Recently, feed ingredient prices and availability concerns have resulted in the examination of diet formulations using alternative, locally available, high protein feed ingredients. An experiment was carried out to evaluate sunflower cake （SC） dietary effect on the performance of ISA brown pullets. The duration of the experiment was 20 weeks. A total of 48 one-day-old pullets were randomly allocated in three groups （C, SC6.25 and SC12.5） with four replications. The pullets of the control group （C） were given proper full rations without sunflower cake for the 1 st, 2nd and 3rd rearing ages, whereas in the treatment groups 5C6.25 sunflower cake was added at 6.25% of rations and in group SC12.5 at 12.5% of rations. The pullets were housed in floor pens with litter and were offered feed and water ad libitum. According to the results of statistical analysis, the addition of 6.25% sunflower cake in the diet significantly （P 〈 0.05） affected body weight gain and feed conversion ratio. The results of this study showed that sunflower cake can be added to the ration of ISA brown pullets of 0-20 weeks of age up to 12.5% without any adverse effect on their performance.

Specificity of Various Mitochondrial DNA (<i>mt</i>DNA), <i>ND5</i>, <i>D-Loop</i>, and <i>Cty-b</i>DNA Primers in Detecting Pig (<i>Sus scrofa</i>) DNA Fragments

Polymerase Chain Reaction (PCR) is an accurate, simple and fast analytical method. This technique is widely used in the identification of meat adulteration and meat-based processed food products. Three Mitochondrial DNA (mt-DNA) primers NADH Dehydrogenase sub unit 5 (ND5), D-Loop, and Cytochrome b (Cyt-b) were tested for their specificity in detecting of pig (Sus scrofa) DNA fragments. DNA genome from 6 meat samples (pork, beef, goat, lamb, and chicken) was amplified by PCR technique using three pairs of primers (ND5, D-Loop, and Cyt-b) and sequenced. The results of amplification using the three primers produced specific DNA bands with the lengths of 232 bp, 951 bp, and 404 bp, respectively. Comparison results with ND5, D-Loop, and Cyt-b gene sequences resulted in similarity values of 100%, 97%, and 99%, respectively. These showed that the mt-DNA primers of ND5, D-Loop, and Cyt-b genes can be recommended as specific primers in detecting pig (Sus scrofa) DNA fragments.

Single Nucleotide Polymorphism Genotyping of Calpastatin Gene Using the ARMS Compared with the RFLP

Calpastatin is an endogenous inhibitor of calpain which is responsible for the breakdown of myofibrillar proteins, The association of Single Nucleotide Polymorphism （SNP） in the calpastatin gene with meat tenderness is an important topic in meat production. Therefore efficient procedure to investigate the SNP is necessary. The objectives of this study were to detect the SNP of calpastatin gene at domain L marker （G/C transversion） of the Kamphaengsaen beef breed （KPS cattle; n = 26） by the Amplification Refractory Mutation System （ARMS） compared with the Restriction Fragment Length Polymorphism （RFLP） methods and to determine the genotypes of the KPS cattle at that marker. Genomic DNA of calpastatin gene extracted from blood of the KPS cattle was detected with ARMS and RFLP methods. The ARMS system has utilized two primer pairs to amplify the two different alleles of a polymorphism in single PCR reaction to detected single base mutation. In this method, the alleles-specific primers had a mismatch at 3＇ terminal base and a second deliberate mismatch at position -2 from 3＇ terminus. While the RFLP method detected a polymorphism using PCR-base technique follow by RsaI restriction enzyme. Amplification of the ARMS method revealed that the results were not different from the conventional method of RFLP. Analysis of genotypes revealed that the KPS cattle inherited the CC, CG and GG genotypes at domain L marker. These were reliable when verified by nucleotide sequence analysis of PCR products. The animals were genotyped and determined for tenderness phenotype with this marker that predicted variation of an intronic polymorphism at domain L of the calpastatin gene. Therefore, the ARMS method was simple, efficient technique, and suitable for detecting SNP at domain L marker of the calpastatin gene.

The Influence of Organic Manure and Biochar on Cashew Seedling Performance, Soil Properties and Status

A nursery experiment was conducted at Cocoa Research Institute of Nigeria to evaluate the impact of manure on cashew seedlings. Treatments consisted of biochar, compost, combination of biochar + compost and a control. Treatments were applied at rate of 0 g (control), 5 g compost, 5 g biochar and 2.5 g each of biochar and compost combination into 5 kg soil in pots, laid out in a completely randomized design (CRD) with three replications. The experiment was monitored for four months in the greenhouse. Data were collected on number of leaves, plant height, stem girth, soil nutrient composition and nutrient uptake, all analyzed using analysis of variance. The treated soils were also assayed on Potato Dextrose Agar for associated mycoflora. The study showed that the soil PH, N, P, K, Ca and Mg were equally enhanced significantly relative to the control, while Aspergillus, Trichoderma, Beauverie, Penicillium, Lasiodiplodia and Rhizopus cultured treated soils shows that Trichoderma harzianum and Beauverie bassiana were significantly higher in combination of biochar and compost treated soil and posed that their bio-control potential is coupled with soil fertility enhancement characteristics. The results also indicate that stem girth and number of leaves were significantly (P ≤ 0.05) different with respect to applied treatment at the first month after treatments application. The leaf area was not enhances with the application of biochar. Combination of biochar + compost significantly enhanced number of leaves and stem girth at the 4th and 12th weeks after planting. Similarly leaf K and P uptake were significantly (<0.05) increased by the application of organic compost and biochar irrespective of whether combined or not compared to the control seedlings. The effect of biochar and compost on cashew leaf Ca and Mg uptake were not significantly different from the control but had a higher value relative to the control. It could therefore be recommended that addition of compost and biochar for sustainable production of cashew seedlings in the nursery be embraced by prospective cashew farmers and seedlings distribution in Nigeria.

Optimization on Pretreatment and Enzymatic Hydrolysis of Sugarcane Trash for Ethanol Production

The present study was conducted for the optimization of pretreatment and enzymatic hydrolysis of lignocellulosic biomass （sugarcane trash）, which is a renewable resource for the production of bioethanol. The pretreatment and enzymatic hydrolysis conditions including alkali （NaOH）/dilute acid （H2SO4）, substrate and chemical concentration for pretreatment, enzyme dosage, pH, temperature and substrate concentration for hydrolysis were varied and evaluated for sugar and ethanol production at the end. The optimum condition was accomplished using 15% w/v DS of 0-2 mm sugarcane trash in size of particle. It was pretreated with two steps of 2% w/v NaOH autoclaving followed by 2% w/v H2SO4 autoclaving with washing step after pretreatment. An enzymatic hydrolysis was then performed using 15% w/v DS pretreated substrate, hydrolyzed with cellulase 50 filter paper unit （FPU）/g DS at 50 ℃ and pH 5. After incubating at 160 r for 48 h, 117.16 g/L reducing sugar was obtained. The achieved sugar after enzymatic hydrolysis was finally fermented to ethanol by Saccharomyces cerevisiae TISTR 5596, with concentration of 48.17 g/L ethanol or yield 0.509 g/g reducing sugars which was equal to 99.81% of theoretical yield.

The Nutrient Quality of Cassava by Addition of Cow Rumen Fluid Enzyme

The research was conducted to study the effect of crude enzyme from cow rumen fluid on nutrient quality of cassava substrates through hydrolysis method. Completely randomized design （CRD） in this research consisted of 4 materials from cassava with its 11 combinations （the total was 15 treatments） with 3 replications. The fifteen treatments were tuber （T）, leaves （L）, peel （P）, onggok （O）, tuber ＋ leaves （TL）, peel ＋ tuber （PT）, tuber ＋ onggok （TO）, leaves ＋ peel （LP）, peel ＋ onggok （PO）, onggok ＋ leaves （OL）, leaves ＋ tuber ＋ peel （LTP）, leaves ＋ tuber ＋ onggok （LTO）, peel ＋ leaves ＋ onggok （PLO）, peel ＋ tuber ＋ onggok （PTO）, peel ＋ leaves ＋ tuber ＋ onggok （PLTO）. Rumen fluid was centrifuged at 10,000 rpm for 15 minutes in 4 ~C. Supernatant was reacted with ammonium sulphate （60%） and incubated in the freezer at 4 ~C for 24 hours. The ground cassava was added by rumen fluid crude enzyme at the dosage of 1% （b/v）. The cassava substrates were kept for 24 hours in room temperature. The addition of rumen fluid enzyme on cassava did not significantly affect dry matter losses （0.96%-2.08%）, but it significantly decreased crude fiber （8.61%-17.83%）. And On the other hand, it increased total sugar （15.19%-29.52%）. The conclusion of this research was that the addition of rumen fluid enzyme on cassava substrates was able to decrease crude fiber （17.83%） and the best total soluble sugar was in tuber （29.52%）, but for dry matter, it was similar to control in the range of 0.96%-2.08%.

Tillage and Poultry Manure Effects on Soil Physical Properties, Nutrient Status, Growth, Dry Matter and Grain Yield of Sorghum

The effects of different tillage systems and poultry manure on soil physical properties, performance and nutrients in sorghum were studied for three years at Owo, southwest Nigeria. There was factorial combinations of herbicide-based zero tillage （ZT）, manual clearing （MC）, disc ploughing （P）, ploughing plus harrowing （P＋H） and ploughing plus double harrowing （P＋2H）, and two rates of poultry manure at 0 and 7.5 Mg ha^-1. Herbicide-based zero tillage and manual clearing reduced soil temperature and conserved more water than mechanized tillage techniques. Poultry manure reduced soil bulk density and temperature and increased soil water and porosity. There was a percentage decrease of leaf N, P, K, Ca and Mg concentrations, plant height, leaf area, stem girth, root dry weight, dry matter and grain yield in ascending order for herbicide-based zero tillage, manual clearing, ploughing, ploughing plus harrowing and ploughing plus double harrowing while percentage increases were recorded in a descending order for all the various combinations of tillage with poultry manure in that order. Poultry manure in combination with tillage increased dry matter and grain yield by 33.1 and 39.5%, respectively in comparison with tillage only. The manure-zero tillage methods increased dry matter and grain yield by 8% and 15%, respectively when compared with manure-mechanized tillage methods. Zero tillage or manual clearing in combination with 7.5 Mg ha^-1 poultry manure was most suitable for sorghum cultivation.

中波紫外线UV-B辐射对酸橙(Citrus latifolia Tan).果实采后贮藏中叶绿素降解酶活性和品质的影响

研究了中波紫外线(UV-B)辐射对酸橙果实采后贮藏过程中叶绿素降解酶活性和果实品质的作用效果。将绿熟的酸橙果实用19.0 kJ.m-2剂量的UV-B照射后,在25℃下避光贮藏,以未照射紫外线的果实为对照。结果表明,UV-B处理有效延缓了果实色度和叶绿素a含量的下降;果实叶绿素降解酶、叶绿素酶、叶绿素降解过氧化物酶和脱镁叶绿素水解酶活性受到抑制,并且脱镁螯合作用也被延缓。UV-B处理促使酸橙果实在贮藏过程中柠檬酸含量逐渐增加,同时抑制了糖含量的增加。此外,在贮藏过程中,处理和对照酸橙果实的抗坏血酸含量均有所下降,但对照果实的下降速度要高于处理果实。以上结果说明UV-B处理可以通过控制叶绿素降解酶的反应来有效抑制酸橙果实贮藏过程中叶绿素的降解,并改善绿熟酸橙的品质。