Mullaorganismide biogeograafia

Väitekirja elektrooniline versioon ei sisalda publikatsiooneMullamikroobide ja -loomade rühmad reguleerivad maapealset elurikkust ja ökosüsteemide toimimist. Ülevaatelisi ja vaatlustel põhinevaid uuringuid tehes tuvastasin, kuidas ruumi, keskkonna ja taimeliikide muutused mõjutavad mullaorganismide kooslusi ja elurikkust ning millised ökoloogilised protsessid on peamiste organismirühmade koosluse varieeruvuse aluseks. Võtsin kasutusele taimede mükoriisa niširuumi (PMNS – plant mycorrhizal niche space) mõiste, mis tähistab taimede võimet kasutada ja kujundada mükoriissete seente kogumit. Selle väärtus sõltub taime mükoriissetest seostest ja funktsionaalsetest tunnustest. Lõin mudeli, et jaotada taimeliike erinevatesse PMNS-idesse, mis võimaldab ennustada mullas leiduvate mükoriissete seente kooslust konkreetses elupaigas. Lisaks määrasin taimeperekonna lepp (Alnus) liikide ja nendega seotud mükoriissete seente, ruumiliste, edaafiliste ja klimaatiliste tegurite suhtelise panuse mükoriissete juurtega seotud bakterikoosluste struktuuri. Leidsin, et mõned arvukad bakterite taksonid on liigispetsiifilised teatud lepaliikidele. Valikuprotsesside olulisus oli suurem väikesemate ja laiema nišiulatusega organismide kooslustes. Globaalse mullauuringu põhjal tuvastasin, et mulla pH ja aasta keskmine sademete hulk olid vastavalt eukarüootsete mikroobide ja loomade koosluste struktuuri peamised määrajad. Eukarüootide rühmadel esinesid vastandlikud elurikkuse mustrid laiuskraadi gradiendil. Minu doktoritöö viitab taimede funktsionaalsete tunnuste suurele tähtsusele mulla mükoriissete seenekoosluste struktureerimisel. Seened vahendavad taimedevahelist konkurentsi nii, sarnase PMNS-iga taimedel on negatiivne seos. Doktoritöö rõhutab ka biootiliste muutujate olulisust juurtega seotud bakterikoosluste kujundamisel ja näitab, et globaalses mastaabis on juurtega seotud ja mullabakterite koosluste aluseks erinevad bioloogilised protsessid. Mulla eukarüootidel esineb positiivne seos keha (raku) suuruse ja niši laiuse vahel ning nende biogeograafilisi mustreid juhtivate ökoloogiliste protsesside ja keskkonnategurite suhtelise mõju vahel.Belowground microbial and animal organism groups significantly regulate aboveground biodiversity and the functioning of terrestrial ecosystems. By conducting review and research studies, we examined how spatial, environmental, and plant species changes affect the belowground composition and diversity and what ecological processes underlie the community variations in association with organism functional groups. We introduced plant mycorrhizal niche space (PMNS) as a plant’s ability to exploit and shape the mycorrhizal fungal pool depending on its dependency on mycorrhizal status and plant functional traits. We provide a model to classify plant species into different PMNS, helping to predict soil mycorrhizal fungi community in a particular habitat by comparing PMNS distance between plant species. Further, we found that the Alnus species phylogeny was the primary determinant for the composition of root-associated bacterial communities, followed by edaphic, spatial and climate variables. In addition, we found Alnus species-specificity for some highly abundant bacterial phylotypes. Our analysis also showed that the importance of selection processes was higher in the community assemblage of smaller-bodied and wider niche breadth organisms. Soil pH and mean annual precipitation were the primary determinants of the community structure of eukaryotic microbes and animals, respectively. We further found contrasting latitudinal diversity patterns and strengths for soil eukaryotic microbes and animals. Taken together, this thesis shows the role of plant functional traits in structuring soil mycorrhizal communities mediating plant-to-plant competition such that there is a negative relation between the similarity of PMNS and the role of mycorrhizal fungi in plant invasion and alteration of mycorrhizal fungi following invasion. It also highlights the importance of biotic variables in shaping root-associated bacterial communities and shows that different processes underlie root-associated and soil bacterial communities on a global scale. Finally, our results point to a potential link between body size and niche breadth in soil eukaryotes and the relative effect of ecological processes and environmental factors in driving their biogeographic patterns.https://www.ester.ee/record=b550745

A comparison of yield potential and cultivar performance of 20 collected purslane (Portulaca oleracea L.) accessions employing seeds vs. stem cuttings

A glasshouse experiment was conducted in Universiti Putra Malaysia (UPM) to evaluate the regeneration and yield potential in purslane using both seeds and stem cuttings of 20 collected accessions from different locations in Western Peninsular Malaysia. Analysis results revealed significant variations (P< 0.05) for morphological traits viz., plant height, number of main branches, number of nodes, internodal distance, stem diameter, number of leaves, leaf area, number of flowers, root length, fresh and dry weight but no significant difference were observed for physiological traits viz., total chlorophyll, net photosynthesis, stomatal conductance, transpiration, water vapor deficit and for either major micro or macro minerals. Hope our research findings will eliminate the doubt of using cutting methods for purslane propagation and cultivation among producers and consumers and will promote their determination to follow purslane production in this summer at any season and anywhere. To the best of our knowledge, this is the first attempt to evaluate and to detect any significant variations arising in morphological, physiological, and especially mineral nutrition in purslane propagated through cuttings vs. through seeds

Allelopathic effects of Batawali (Tinospora tuberculata) on germination and seedling growth of plants.

A study was undertaken to explore the effects of methanol extracts (100,50, 25, 12.5 and 6.25 g/l) from the dried powders of aerial parts of Batawali (Tinospora tuberculata) on emergence and initial growth of rice, radish, lettuce and carrot as represented by germination percentage, radical and hypocotyle length. Results indicated that both stem and leaves of Batawali markedly raised the suppression of germination and primary growth of all examined crops when plants were exposed to increasing the methanol extract concentrations from 6.25to 100 g/l of distilled water. The half-inhibitory concentrations that inhibit germination (ECg50), radicle (ECr50) and hypocotyle (ECh50) growth weredetermined for both the extracts. According to these values, an index (Re) was calculated in order to establish a ranking of the most sensitive plants and most effective extract. It was observed that the leaves extract was more active than the stem extract and caused the greatest negative effect on germination and early growth of plants. All tested plants differed in their sensitivity to T. tuberculata extracts. Higher reduction in plant growth parameters was observed in carrot. The tested extracts inhibited mainly the growth of radicle more than the growth of the hypocotyle and germination percentage in all examined crops, except carrot. According to the study, it could be concluded that T. tuberculata extracts had a significant herbicidal activity which depended on the extract concentrations, plant parts and the target crops

Effects of Tinospora tuberculata leaf methanol extract on seedling growth of rice and associated weed species in hydroponic culture

The study was conducted to evaluate the responses of rice and rice weed seedlings (barnyardgrass and weedy rice) at the three-leaf stage to Tinospora tuberculata leaf methanol extract (3.12, 6.25 and 12.5 g L−1) under hydroponic culture. It shows that the leaf methanol extract had various degrees effects depending on target plant species and each tested index (biomass, root length, shoot length, transpiration volume, chlorophyll a, chlorophyll b and carotenoid contents). The effective concentration of the leaf extract capable of reducing 50% of rice growth was higher than those of target weed species. Moreover, the root length was more tolerant to leaf methanol extract in comparison to the other plant parameters measured. A greater reduction was observed in chlorophyll a content compared to chlorophyll b and carotenoid. The results revealed that the reduction of transpiration volume closely coincided with the magnitude of growth inhibition of tested plants. Ultra-fast liquid chromatography analysis revealed 11 of 32 peaks in chemical profile, including benzoic acid, caffeic acid, chlorogenic acid, isoorientin, isovitexin, orientin, p-anisic acid, syringic acid, trans-cinnamic acid, trans-ferulic acid, and vitexin have the same retention time with those peaks of the extract. The amount of compounds was present in the range of between 4 817 and 115.5 mg kg−1 dry weight (DW). The concentration-response bioassay of all 11 individual compounds and their equimolar mixture against the seeds of barnyardgrass revealed their contribution in the allelopahic activity of T. tuberculata leaf extract. The examined compounds and their combination exhibited various degrees of growth inhibitory effects on the early growth of barnyardgrass. Therefore, the specific number, concentration, combination and inhibitory activity of bioactive compounds leads to allelopathy activity of T. tuberculata leaves which could be employable directly as a natural herbicide and its growth inhibitor compounds can be used as a template for producing new herbicides

Collection and identification of different Purslane (Portulaca oleracea L.) accessions available in Western Peninsular Malaysia

Purslane (Portulaca oleracea L.) is widely distributed around the globe and is popular as a beneficial herb in many areas of Europe, Asia, and the Mediterranean region. It is already very well known for its nutritional as well as medicinal values for both human and animal feeds. It is a rich source of potassium, magnesium, calcium and possesses the potential to be used as vegetable source of omega-3 and 6 fatty acids. It is very good source of alpha linolenic acid and gamma-linolenic acid of any green leafy vegetable. It also contains high amount of α-tocopherol and ascorbic acid. The antioxidant content and nutritional value of purslane are important for human consumption. It revealed tremendous nutritional potential and has indicated the potential use of this herb for the future. Purslane is a very fast-growing plant and can reproduce vegetatively from stem cuttings by forming adventitious roots from the cut end of the stem. Recently many plant species are threatened with extinction through human activity and the force of globalization. Plant collections are a valuable tool both in research and as a valid means of providing students at many educational levels with knowledge of and appreciation for the wonder, diversity, and beauty of plant life. Collection of diverse accessions, identification, preservation and proper management of such beneficial plants is very important for their diversity analysis which is essential for present and future human well-being. The identification of representative and manageable subset of accessions would facilitate access to the diversity available in large collections. Giving importance on the above matters a total of 45 different purslane samples were collected from different locations of Western Peninsular Malaysia, properly identified and subjected for future detailed analysis of morpho-physiological and nutritional variations among the collections

Screening of Purslane ( Portulaca oleracea

Purslane (Portulaca oleracea L.) is an herbaceous leafy vegetable crop, comparatively more salt-tolerant than any other vegetables with high antioxidants, minerals, and vitamins. Salt-tolerant crop variety development is of importance due to inadequate cultivable land and escalating salinity together with population pressure. In this view a total of 25 purslane accessions were initially selected from 45 collected purslane accessions based on better growth performance and subjected to 5 different salinity levels, that is, 0.0, 10.0, 20.0, 30.0, and 40.0 dS m−1 NaCl. Plant height, number of leaves, number of flowers, and dry matter contents in salt treated purslane accessions were significantly reduced (P≤0.05) and the enormity of reduction increased with increasing salinity stress. Based on dry matter yield reduction, among all 25 purslane accessions 2 accessions were graded as tolerant (Ac7 and Ac9), 6 accessions were moderately tolerant (Ac3, Ac5, Ac6, Ac10, Ac11, and Ac12), 5 accessions were moderately susceptible (Ac1, Ac2, Ac4, Ac8, and Ac13), and the remaining 12 accessions were susceptible to salinity stress and discarded from further study. The selected 13 purslane accessions could assist in the identification of superior genes for salt tolerance in purslane for improving its productivity and sustainable agricultural production

Growth performance of roselle (Hibiscus sabdariffa) in response to oil palm by-product media and controlled release fertilizer

A study was carried out to optimize the best ratio of empty fruit bunch (EFB) of oil palm as soilless culture media for growth performance of roselle, to investigate the optimum level of slow-release fertilizer for biomass production and to measure the interaction between different ratio of media and rate of fertilizer on growth of roselle. As treatment 4 different media (M1 = Top soil, M₂ = 1 Top soil: 1 sand, M₃ = 2 Top soil: 1 EFB: 1 Sand, M₄ = 3 Top soil: 2 EFB: 1 Sand) and 4 different control released fertilizer (CRF) rates (F₁ = Control (80 kg/ha NPK), F₂ = 40 kg/ha Kamila, F3 = 80 kg/ha Kamila and F₄ = 120 kg/ha Kamila) were applied in this experiment. Media treatment M1 indicated a good response in number of branches, stem diameter, total number of calyxes and shoot dry weight compared to other 3 media. While M₃ and M₄ gave better respond on total leaf area and nutrient content (N, P and K) in plant tissue of roselle. Whereas for different rates of fertilizer applied, treatment F₃ (80 kg/ha Kamila CRF) exhibited the better performance on growth of roselle plants. Significant differences were observed for N, P and K nutrient uptake in fertilizer treatments compared to media treatments

Allelopathic effect of methanol extracts from Tinospora tuberculata on selected crops and rice weeds

Herbicidal potential of aerial parts of Tinospora tuberculata on germination and seedling growth of seven test plant species, namely rice (Oryza sativa L.); two rice weeds, barnyardgrass (Echinochloa crus-galli L.) and weedy rice (O. sativa f. spontanea); and four vegetable crops, lettuce (Lactuca sativa L.), tomato (Solanum lycopersicum L.), carrot (Daucus carota L.), and cucumber (Cucumis sativus L.) were evaluated. Six concentrations of methanol extract (3.12, 6.25, 12.5, 25, 50, and 100 g L−1) were compared with the control (distilled water). The rate of seed germination and the radicle and hypocotyl length of 7-day-old test plant seedlings were reduced as the concentration of extracts increased compared to the control. Generally, the degree of toxicity of extracts derived from the leaves was more than the extracts derived from the stem. Cluster analysis and the concentrations required for 50% inhibition (defined as EC50) of all parameters showed that radicle growth was more suppressed than germination and hypocotyl growth. Lettuce and carrot were observed as the most sensitive plants while rice showed the highest tolerance to both extracts. Moreover, the dicot target plants were affected more severely than the monocots when treated with leaf extract. The chemical composition of the T. tuberculata methanolic extracts was analyzed by a GC–MS system. A total of 92 and 22 constituents (not previously identified) were found in the leaves and stem, respectively. The results showed that 17 of the 92 components in the leaves, as compared to 4 of 22 compounds in the stem, are known as toxic compounds. These results suggest that T. tuberculata contains a significant source of plant growth inhibitors with potential for the development of future natural herbicide

Growth, physiology and fruit quality of Hibiscus sabdariffa L. in response to regulated deficit irrigation

The effects of deficit irrigation technique on growth and fruit quality of roselle (Hibiscus sabdariffa L.) was observed. The result shows that minimum weight of the yield was obtained from treatment grown with well watered (WW) condition. Plant height was affected by reduction of water application. Regulated deficit irrigation (RDI) tended to decrease all means of growth parameter except stem fresh and dry weight. RDI shows significant effect on yields, where the reduction of 50% water produce more fruits compared to control plants. The impact of RDI was not significant effect on physiological change of roselle. Thus, RDI could be a feasible technique for Roselle production as it saves large amounts of water with reduction on plant growth but increase the yield as compared to well watered (WW) of roselle

Application of ascorbic acid in maintenance of minimally processed product quality of jackfruit (Artocarpus heterophyllus)

Physiochemical changes of minimal processing of jackfruit (Artocarpus heterophyllus Lam.) were studied by treating with different concentration of ascorbic acid (AA) and stored at different storage temperatures. Result showed that there were significant differences in fresh weight, firmness, ascorbic acid content, titratable acidity (TA), and soluble solid content (SSC), during increasing period of storage in both ambient and cold storage of minimal processed jackfruit. Treatment of different concentration of AA showed significant in fruit firmness, pulp fresh weight and AA content of minimal processed jackfruit kept under ambient temperature. Minimal processed jackfruit keeps under ambient storage exhibit greater fruit weight loss and softening as compared with cold storage. However, the AA content of minimal processed jackfruit increased in ambient storage and it was greater after one day treatment than cold storage fruit