The premetazoan ancestry of cadherins

Cadherin-mediated cell adhesion and signaling is essential for metazoan development and yet is absent from all other multicellular organisms. We found cadherin genes at numbers similar to those observed in complex metazoans in one of the closest single-celled relatives of metazoans, the choanoflagellate Monosiga brevicollis. Because the evolution of metazoans from a single-celled ancestor required novel cell adhesion and signaling mechanisms, the discovery of diverse cadherins in choanoflagellates suggests that cadherins may have contributed to metazoan origins.     

Evaluation of Submergence Tolerance in Landrace Rice Cultivars by Various Growth and Yield Parameters

Journal of Crop Science and Biotechnology - Flash flood causes a serious damage to rice crops in northern and eastern parts of Bangladesh almost every year. This study was designed to identify...     

Evaluation of two concepts of fertilization for wheat in a calcareous soil of Bangladesh

Two popular concepts of soil fertilization, basic cation saturation ratio (BCSR) and sufficiency level of available nutrients (SLAN), were tested on a calcareous soil (Aeric haplaquept) during 1995–1996 at the Bangladesh Rice Research Institute (BRRI) Regional Station Rajshahi using wheat as a test crop. According to BCSR concept the soil was deficient in potassium (K) and according to SLAN concept it was deficient in phosphorus (P), respectively. Potassium dose of 120 kg ha^‐1 [to attain 2% saturation of total cation exchange capacity (CEC) according to BCSR] along with other two doses (0 and 60 kg K ha^‐1) and P dose of 50 kg ha^‐1 (to attain available P at sufficiency level) along with other two doses (0 and 100 kg P ha^‐1) were compared in a randomized complete block design. The application of 50 kg P ha^‐1 significantly increased plant height, spikes m², grains per spike, grain and straw yields of wheat over 0 kg P ha^‐1 with or without K but increasing P dose from 50 to 100 kg P ha¹ did not give additional yields. The agronomic parameters and yields were not affected significantly by K application. Similar results were also observed in nutrient content and nutrient uptake. Thus, SLAN concept appeared as an effective tool for fertilizer recommendation for the calcareous soil while BCSR gave no apparent result there.     

Water and nutrient dynamics of a paddy soil of Bangladesh

The objectives of the study were the changes in water tension, redox potential, and the pH value of a silty Eutric Gleysol from young river sediments near Mymensingh, the nutrient concentration of soil solution, as well as the supply of nutrients by rain, irrigation and fertilizing, and the uptake of nutrients by rice during the year. In the case of nitrogen, a moderate loss was observed, caused by the leaching of NH₄, and significant losses due to volatilisation and denitrification. Fertilized P was enriched in the soil. The leaching of Ca, K, Mg, Na, Cu, Fe, Mn, and Zn was clearly higher than the addition by rain, irrigation and fertilization. It is concluded, that the loss of nutrients was caused by weathering.     

SW—Soil and Water: State Parameter Interpretation of Cone Penetration Tests in Agricultural Soils

Cone penetrometer resistance in saturated sands has been shown by earlier workers to be an exponential function of a state parameter in critical state space. The present investigation demonstrates that this concept of a state parameter-penetrometer function (SPP-function) also holds good in a partly saturated agricultural soil. The two coefficients which characterize the SPP-function have been evaluated from extensive tests carried out in a miniature penetrometer calibration chamber. These coefficients were found to vary in a systematic manner with the moisture content of the sandy loam soil used in the experiments, as do the three basic parameters necessary to characterize the critical state boundaries of this soil. The paper presents a method of using this experimentally obtained information to interpret the pore space of the soil from measured penetrometer resistance in that soil. The performance of the proposed method was checked against penetrometer readings made under carefully controlled laboratory conditions in an indoor soil tank. The prediction accuracy was poor, but it is felt that this could be improved by using an iterative solution in place of the single step method used in the validation. The tedious and time consuming experimental work described in the paper is confined to a single sandy loam soil, typical of a light agricultural soil. In order to generalize the solution, it is necessary to test the procedure over a wide range of soils, including clay. If the SPP-functions can be established for these conditions then the state parameter concept could prove to be a powerful tool in the interpretation of cone penetrometer readings.