In order to study the drought sensitivity of pea (Pisum sativum L. cv. Bodil) during different growth phases, a field experiment was conducted in 1985 and 1986 on coarse textured sandy soil with low water-holding capacity. Drought occurred naturally or was imposed by shelters during the vegetative, the flowering and the pod filling growth phase, respectively. Drought sensitivities were assessed as the ratio between relative yield decrease (1 -y,/ym) and relative evapotranspiration deficit (1 -ETa/ET m) of the individual growth phases, where Ya and ETa are the actual yield and evapotranspiration, respectively, of a drought stressed plot and Ym and ETm are the maximum yield and evapotranspiration of the fully irrigated treatment. Root growth was followed by measuring root density (Lv) in 10 cm soil layers to a depth of 50 cm. The leaf osmotic potential at full hydration (~1oo) was measured in the last fully developed leaf during the growing season.The available water capacity was estimated to be 42-50 mm on the basis of a plot of ETJETm versus soil water deficit measured by the neutron moderation method or direct measurement of the root depth. The root zone with Lv > 0.1 cm-2 only reached a depth of 35 cm at the end of the flowering phase and a depth of 45-50 cm at maturity. Root growth continued during the drought periods. The drought sensitivity of pea was high during the flowering phase, especially in 1986 when water stress developed rapidly, and considerably lower during the pod filling phase. The yield reduction caused by drought in the flowering phase was mainly the result of a lower number of pods per stalk. Severe drought did not occur during the vegetative phase. The leaf osmotic potential (~1oo) dedined from c. -0.75 MPa to c. -1.30 MPa during the growing season. Osmotic adjustment was largest during drought in the early growth phases; in 1985 ~oo decreased 0.5 MPa under relatively slow drought development during the flowering phase while in 1986, when drought stress developed rapidly, ~oo only decreased Offprint requests to: M. Neumann Andersen 0.2 MPa. Osmotic adjustment may have caused the lower drought sensitivity in 1985 than in 1986 and mediated the continued root growth during drought.

Weed interference is a major threat to rice production, leading to high yield reduction and reduced profitability. Therefore, field experiments were conducted to evaluate the effect of the different timings of weed control on the growth and yield of upland rice in the 2015 and 2016 cropping seasons. The treatments consisted of periods when the crop was allowed to be weed-infested for the first 3, 6 and 9 weeks after sowing (WAS) and periods when the weeds were controlled for the first 3, 6 and 9 WAS. Two treatments of weed infestation and weed control until harvest were also included as the checks in a randomized complete block design with three replications. In both years, rice grain yields ranged from 0.6 to 0.8 t ha-1 in plots kept weed-infested until harvest, and from 3.5 to 3.9 t ha-1 in plots kept weed-free until harvest, indicating a 79-83% yield loss with uncontrolled weed growth. Weed infestation for the first 3 WAS did not cause a significant reduction in the growth and yield of rice provided the weeds were removed thereafter. However, the delay in weed control until 9 WAS reduced rice growth and resulted in irrevocable yield reduction. It was only necessary to remove the weeds between 3 and 9 WAS for optimum grain yield, as no significant yield increase was observed in weed control after 9 WAS in both years. This study showed that weed control between 3 and 9 WAS would give the optimum growth and yield of upland rice.

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The synthesis of guanidine derivatives of benzimidazole namely, guanidinobenzimidazole, (GBM), guanidinophosphonatebenzimidazole, (GPBM), and their chelating properties are reported in this work. The guanidine and phosphonate derivatives were synthesized along with their metal complexes, Fe(II), Co(II), Ni(II) 1 13 Cu(II) and Zn(II). The ligands were characterized by H NMR, C NMR spectroscopy while both the ligands and the metal complexes were characterized by C.H.N analysis, Percentage Metal Composition, FT-Infrared spectra Analysis , UV-Visible Electronic Spectroscopy and Magnetic susceptibility measurements. The results from the percentage composition of the metals in the complexes suggest that ratio of the metal to ligand is 1: 2 (M: L) where M = Co(II), Ni(II), Cu(II), Fe(II), Zn(II). Thus, the prepared complexes have the general formulae [ML ]. Electronic Spectral analyses indicated the participation of the imidazolic nitrogen atom and the nitrogen 2 in position 12 of the guanidinobenzimidazole ligand in the coordination of the ligand to the metal ions while, the shifts in the position of theν(P=O) absorption band of the phosphonate moiety in the-1-1 guanidinophosphonatebenzimidazole, (GPBM) ligand from 1265 cm in the free ligand to 1141-1200 cm in the metal complexes suggested that the P=O is most likely involved together with the nitrogen atom in position 12 in the coordination of the metal ions to the guanidinophosphonatebenzimidazole, (GPBM) ligand. The electronic spectral data and the values of the magnetic susceptibility values suggest six coordinate octahedral/ distorted octahedral geometry for all the complexes.

Hydrazones and their coordinated compounds were prepared for antimicrobial activi ties investigation while hydrazides were prepared from their esters. The hydrazides were reacted with benzaldehyde to produce benzoylhydrazone, m-nitrobenzoylhyd razone, p-nitrobezoylhydrazone, 3,5 dinitrobenzoylhydrazone, p-aminobenzoylhyd razone and m-aminobenzoylhydrazone in white, off white, light-yellow, deep-yellow and light-brown colours. Complexes were synthesized from strontium chloride and the hydrazones which produced off-white, grey, light-brown and dark-brown complexes. The ligand-metal compounds were analyzed through complexometric titration while characterization of all the samples were based on spectra data. Metal to hydrazone stoichiometry of 1:0.5 to 1:3 were proposed for the complexes. Relevant assignments were made in the hydrazones and complexes for possible points of coordination. Physicochemical properties of the ligands and their coordinated compounds were determined. Antimicrobial Properties of the compounds demonstrated good performance on Streptococcus faecalis, Clostridium sporosenes, Baccillus anthracis, Pseudomonas fluorescenes, Saccharomyces cerevisiae and Hansenula anomala. Nanohybrid study of the samples is recommended for future studies on the antimicrobial activities.