UV-B Effect on Constituents of Azolla caroliniana

2007 ◽  
Vol 62 (3-4) ◽  
pp. 246-252 ◽  
Author(s):  
Mohamed M. Ibrahim ◽  
Eazaz M. Mostafa

Abstract Changes in growth and ultrastructure of Azolla caroliniana in response to elevated UV-B radiation were investigated. Exposure of plants to UV-B radiation for 1, 8, 16, 24 and 48 h exhibited a significant decrease in biomass and relative growth rate. This decrease resulted in an increase in doubling time over the control. Also, Chl a and b contents were significantly decreased especially after 16 h. The reduction was accompanied by a decrease in 5-aminolaevulinic acid content (precursor of chlorophyll). On the other hand, contents of carotenoid and UV-absorbing phenolic compounds (flavonoids and anthocyanins) were increased.

2015 ◽  
Vol 95 (1) ◽  
pp. 20-26 ◽  
Author(s):  
E.M. Mostafa ◽  
A.M.A. Hassan

Exposure ofAzollaplants to UV-B radiation for 6 h resulted in a decrease in biomass and relative growth rate (RGR), which coincided with an increase in doubling time (DT) as compared with the control. Also, the protein content decreased. On the other hand, hydrogen peroxyde (H2O2) and malondialdehyde (MDA) accumulated significantly in UV-treatedAzollaplants. Conversely, the addition of selenium (Se) at 1 ppm resulted in a significant increase in biomass and protein content of untreated and UV-treatedAzollaplants, and a significant reduction in both H2O2and MDA. Moreover, the addition of Se to UV-treated and untreatedAzollaplants resulted in a significant increase in total ascorbate and total glutathione (GSH) contents compared with the control and UV-stressedAzollaplants. Also, glutathione redox potential (GSH/TG) increased significantly in UV-treatedAzollaplants in the presence of Se. There also was a significant increase (38%) in ascorbate peroxidase (APX) activity in UV-treated plants compared with the control. APX activity in the presence of Se did not change significantly compared with the control. Glutathione reductase (GR) activity increased significantly in UV-treatedAzolla, while glutathione peroxidase (GSH-PX) activity did not. On the other hand, both GSH-PX and GR activity in untreated and UV-treatedAzollaplants were significantly enhanced by the application of Se to the nutrient media at a concentration of 1 ppm. Therefore, we can conclude that Se protectsAzollaplants from UV-B stress.


2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Oladosu O. Oladimeji ◽  
Olayanju O. Oladimeji

This research paper's main objective is to quantify and analyze the research output of data mining in West Africa, including (1) growth in publications as measured by the Relative Growth Rate (RGR) and Doubling Time (Dt), (2) productivity and quantification of research output for different institutions of the region (West Africa).


2014 ◽  
Vol 15 ◽  
pp. 47-53 ◽  
Author(s):  
Nosheen Fatima Warriach ◽  
Muzamil Tahira

This study explores the research trends at Pakistani universities by highlighting the use of Information and Communication Technologies (ICTs) in the research process and its productivity. It also investigates the impact of Higher Education Commission (HEC) initiatives for research output in Pakistani universities in general and PU, in particular. It explores the essential ICT skills to increase research productivity as perceived by researchers from the Faculty of Social and Behavioral Sciences through structured interviews. An analysis of HEC of Pakistan and PU websites is carried out. The statistics of these websites shows that there is an increase in the number of research articles and PhDs produced every year. Data show that the respondents are not fully utilizing the pricey electronic sources provided by the HEC, yet there is a yearly increase in a number of PhDs produced and published research. The relative growth rate of research productivity and doubling time were not constant. It is also observed that doubling time has increased while the relative growth rate is going to decrease.


2018 ◽  
Vol 38 (04) ◽  
pp. 387-393 ◽  
Author(s):  
Abdul Manan Dogar ◽  
Mahmood Ayyaz ◽  
Naeem Abbas ◽  
Sarfraz Ali Shad ◽  
Afifa Naeem

AbstractCotton mealybug,Phenacoccus solenopsisTinsley is an important polyphagous insect pest and causes severe losses to different crops worldwide. In the current study, we investigated the effect of different host plants, such asCaesalpinia pulcherrima,Plumeria rubra, Anthurium andraeanum, Jasminum sambac, andHibiscus rosasinensis, on the biological parameters ofP. solenopsis. The survival rate from crawler to adult, female nymphal duration, development time from crawler to female adult, and female adult weight were significantly different on the different hosts. Male nymphal duration, development time from crawler to male adult, pupal weight, emergence rate of male adults, and mean relative growth rate for male were similar on all the tested host plants. Pupal duration and generation time of male and female onH. rosasinensiswere significantly shorter than on the other hosts. Adult male and femaleP. solenopsislongevity was significantly shorter onH. rosasinensiscompared to other hosts. The fecundity was lower onC. pulcherrimaandA. andraeanumand hatchability was lower onC. pulcherrimathan on the other hosts. The net reproductive rate, the intrinsic rate of natural increase, and biotic potential and mean relative growth rate for female ofP. solenopsiswere significantly different on the tested hosts. Our results point to the role of host plants in increasing the populations ofP. solenopsisand could help to design cultural management strategies.


2018 ◽  
Vol 19 (2) ◽  
pp. 183 ◽  
Author(s):  
Lismining Pujiyani Astuti ◽  
Indriatmoko Indriatmoko

ABSTRACTAquatic plants are important part of aquatic ecosystem that can be used as an phytoremidiation agent, trapping organic matter in eutrophic waters as well as cleaning and controlling heavy metal pollution, pesticides and oil. The aim of research to assess the ability of some aquatic plants to organic matter and phosphate reduction for improve water quality. Research conducted at the Greenhouse of Institution Research for Fishes Resources Rehabilitation in May 2016. The study using factorial completely randomized and all treatment were conducted in triplicate. Aquatic plants are used Azolla sp., Spirodela sp., Duckweed (Lemna sp.), Salvinia sp., Water lettuce (Pistia sp), and water hyacinth (Eicchornia crassipes). Water media used are high stock solution of organic matter derived from fish farming waste water containing undigested, food, faeces and urine of fish. Water sampling was conducted on day 0 (T0), 2nd (T2), 5th (T5) and 9th (T9) after planting. The results showed that the total organic matter) and P-PO4 significantly different based on day of sampling, while the aquatic plant treatment significantly different at P-PO4 concentration, but not significantly different from the organic matter. However, based on the percentage change showed that the wood lettuce (Pistia sp) capable of lowering the BOT and P-PO4 as much as 55.52% and 60.62%, and the water hyacinth can lower both BOT and P-PO4 as much as 23.38 % and 92.68%. Relative growth rate (RGR) was higher in the aquatic plants that tend to be small as Spirodela sp,  Lemna sp and with doubling time (DT) is relatively short. Water hyacinth plants tend to have a lower RGR values and DT are relatively long. The value of RGR and DT related to the availability of nutrients.Keywords: Aquatic Plants, Water Quality, Relative Growth Rate (RGR), Doubling Time (DT)ABSTRAKTumbuhan air merupakan bagian penting dari ekosistem perairan yang dimanfaatkan sebagai agen fitoremediasi, perangkap bahan organik di perairan eutrofik serta membersihkan dan mengontrol pencemaran logam berat, pestisida dan minyak. Tujuan penelitian untuk mengkaji kemampuan beberapa tumbuhan air dalam mengurangi pencemaran bahan organik dan fosfat dalam upaya memperbaiki kualitas perairan. Penelitian dilakukan di laboratorium rumah kaca Balai Riset Pemulihan Sumberdaya Ikan pada bulan Mei 2016. Penelitian menggunakan Rancangan Acak Lengkap Faktorial dengan tiga ulangan. Tumbuhan air yang digunakan Azolla sp., Spirodela sp., Mata lele (Lemna sp.), Kiambang (Salvinia sp.), Kayu apu (Pistia sp.), dan Eceng Gondok (Eicchornia  crassipes). Media air yang digunakan adalah larutan stok tinggi bahan organik berasal dari air limbah budidaya ikan yang mengandung sisa pakan yang tidak tercerna, feses dan urin ikan. Pengambilan sampel air dilakukan pada 0 hari (T0), 2 hari (T2), 5 hari (T5) dan 9 hari (T9) setelah penanaman. Hasil penelitian menunjukkan bahwa bahan organik total (BOT) dan P-PO4 berbeda nyata pada perlakuan hari, sementara perlakuan jenis tumbuhan air berbeda nyata pada konsentrasi P-PO4 namun tidak berbeda nyata pada BOT. Persentase perubahan menunjukkan bahwa kayu apu mampu menurunkan BOT dan P-PO4 sebesar 55,52% dan 60,62% serta eceng gondok mampu menurunkan BOT dan P-PO4 sebesar 23,38% dan 92,68%. Nilai relative growth rate (RGR) lebih tinggi pada tanaman air yang cenderung kecil seperti Lemna sp dan Spirodela sp dengan doubling time (DT) yang relatif pendek. Tanaman eceng gondok cenderung mempunyai nilai RGR rendah dan DT yang relatif lama. Besarnya nilai RGR dan DT berkaitan dengan ketersediaan nutrisi.Kata kunci: Tumbuhan Air, Kualitas Air, Relative Growth Rate (RGR), Doubling Time (DT)


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