Differences Between Rice and Wheat in Temperature Responses of Photosynthesis and Plant Growth

The temperature responses of photosynthesis (A) and growth were examined in rice and wheat grown hydroponically under day/night temperature regimes of 13/10, 19/16, 25/19, 30/24 and 37/31°C. Irrespective of growth temperature, the maximal rates of A were found to be at 30–35°C in rice and at 25–30°C in wheat. Below 25°C the rates were higher in wheat, while above 30°C they were higher in rice. However, in both species, A measured at the growth temperature remained almost constant irrespective of temperature. Biomass production and relative growth rate (RGR) were greatest in rice grown at 30/24°C and in wheat grown at 25/19°C. Although there was no difference between the species in the optimal temperature of the leaf area ratios (LARs), the net assimilation rate (NAR) in rice decreased at low temperature (19/16°C) while the NAR in wheat decreased at high temperature (37/31°C). For both species, the N-use efficiency (NUE) for growth rate (GR), estimated by dividing the NAR by leaf-N content, correlated with GR and with biomass production. Similarly, when NUE for A at growth temperature was estimated, the temperature response of NUE for A was similar to that of NUE for GR in both species. The results suggest that the difference between rice and wheat in the temperature response of biomass production depends on the difference in temperature dependence of NUE for A

A survey of trainee specialists experiences at the University of Cape Town (UCT): Impacts of race and gender

<p>Abstract</p> <p>Background</p> <p>Efforts to redress racial and gender inequalities in the training of medical specialists has been a central part of a dedicated programme in the Faculty of Health Sciences at the University of Cape Town (UCT). This study aimed to describe trends in race and gender profiles of postgraduate students in medical specialties (registrars) from 1999 to 2006 and to identify factors affecting recruitment and retention of black and female trainees.</p> <p>Method</p> <p>Review of faculty databases for race and gender data from 1999 to 2006. Distribution of an anonymous self-administered questionnaire to all registrars in 2005/2006.</p> <p>Results</p> <p>The percentage of African registrars doubled from 10% to 19% from 1999 to beyond 2002. The percentages of Africans, Coloureds and Indians rose steadily from 26% to 46% from 1999 to 2005, as did that of women from 27% to 44%. The institution's perceived good reputation, being an alumnus and originating from Cape Town were common reasons for choosing UCT for training. A quarter of respondents reported knowledge of a friend who decided against studying at UCT for reasons which included anticipated racial discrimination. Black respondents (23%), particularly African (50%), were more likely to describe registrarship at UCT as unwelcoming than white respondents (12%). Specific instances of personal experience of discrimination were uncommon and not associated with respondents' race or gender. Registrars who had had a child during registrarship and those reporting discrimination were more likely to rate the learning and research environment as poor (Odds Ratio, 4.01; 95% CI 0.98 – 16.47 and 1.99 95% CI 0.57 – 6.97, respectively).</p> <p>Conclusion</p> <p>The proportion of black and female registrars at the University of Cape Town has increased steadily from 1999 to 2006, most likely a result of systematic equity policies and procedures adopted in the faculty during this period. The data point to a need for policies to make the institution more welcoming to diversity and for strategies to address institutional culture and mentorship, with an aim to develop examples of best practices to share within and between institutions.</p

Toposequential Variation in Soil Fertility and Rice Productivity of Rainfed Lowland Paddy Fields in Mini-Watershed (Nong)in Northeast Thailand

Mini-watersheds called Nongin Thai are geographical components of rainfed lowland rice culture in Northeast Thailand, and constitute distinct units in understanding environmental constraints for low and unstable rainfed rice production there. The toposequential variation of soil fertility and its relation to rice productivity within mini-watersheds, was examined by phytometry of sampled soils and field measurements of rice growth and yield. The phytometry experiment with irrigated potted rice using soils sampled from various rice fields within each mini-watershed, revealed that soil fertility as evaluated by rice dry matter production showed a 5 times difference among the fields at most. The difference in the soil fertility was ascribed primarily to that in nitrogen (N) supply capacity, which itself had a strong correlation with soil organic carbon (SOC) content. Accordingly, the biomass production of pot-grown rice was proportional to SOC. content, which suggested the usefulness of SOC as an index for soil fertility evaluation. The effect of clay on the soil fertility was much less than that of SOC. The actual rice yield in each field also showed quite large field-to-field variation, most of which was explained by the SOC content, rice growth duration and fertilizer application rate even though water availability also affected the yield. The yield positively correlated with growth duration and hence with earlier transplanting. Both SOC and clay contents of fields showed steep gradients with ascending field elevation within mini-watersheds, resulting in a marked toposequential distribution of rice yield. The toposequential distributions of SOC and clay contents imply that rice culture after deforestation accelerated soil erosion from upper to lower fields. The large toposequential gradient in soil fertility requires different resource and crop management for each toposequential position, in order to improve rice productivity of the mini-watershed as a whole

Συμβολή της ηλεκτρικής τομογραφίας στην χαρτογράφηση καρστικών εγκοίλων στην περιοχή Αεροδρομίου του Ν. Χανίων

Περίληψη: Η παρούσα διπλωματική εργασία πραγματεύεται την επεξεργασία και ερμηνεία της γεωφυσικής διασκόπησης, για τον εντοπισμό καρστικών εγκοίλων κατά την εκσκαφή της επέκτασης του Κρατικού Αερολιμένα Χανίων. Η γεωφυσική έρευνα έγινε με την μέθοδο της ηλεκτρικής τομογραφίας. Τα δεδομένα προέκυψαν μετά από σχετικές μετρήσεις που κρίθηκε απαραίτητο αλλά και αναγκαίο να πραγματοποιηθούν κύρια στη θέση αλλά και στην ευρύτερη περιοχή για την ασφαλή ανέγερση της επέκτασης του κτιρίου.Τα δεδομένα επεξεργάστηκαν με τη χρήση κατάλληλων λογισμικών αλλά και μεθόδων αντιστροφής. Ειδικότερα, χρησιμοποιήθηκαν τρεις μέθοδοι αντιστροφής δισδιάστατων δεδομένων (Least-Squares Inversion, Robust Inversion και Combined) και δύο λογισμικά (Res3Dinv) και (EarthImager3D) για την αντιστροφή των τρισδιάστατων γεωηλεκτρικών δεδομένων. Στην συνέχεια συγκρίθηκαν οι γεωηλεκτρικές τομές και προτάθηκε σαν πιο κατάλληλη μέθοδος αντιστροφής αυτή πουελαχιστοποιεί την νόρμα L1 (Robust). Η τρισδιάστατη αντιστροφή απεικόνισε πολύ υψηλής αντίστασης δομή, η οποία σύμφωνα με τα γεωτρητικά δεδομένα και τις επιφανειακές παρατηρήσεις αποδίδεται σε έγκοιλο το οποίο πρέπει να ληφθεί υπόψη στον σχεδιασμό της θεμελίωσης των νέων κτιρίων του Κρατικού Αερολιμένα Χανίων, ώστε να αποφευχθούν μελλοντικές αστοχίες