Quantifying rice yield gaps and their causes in Eastern and Southern Africa

The demand for rice in Eastern and Southern Africa is rapidly increasing because of changes in consumer preferences and urbanization. However, local rice production lags behind consumption, mainly due to low yield levels. In order to set priorities for research and development aimed at improving rice productivity, there is a need to characterize the rice production environments, to quantify rice yield gaps—that is, the difference between average on-farm yield and the best farmers’ yield—and to identify causes of yield gaps. Such information will help identifying and targeting technologies to alleviate the main constraints, and consequently to reduce existing yield gaps. Yield gap surveys were conducted on 357 rice farms at eight sites (19–50 farmers per site) across five rice-producing countries in Eastern and Southern Africa—that is Ethiopia, Madagascar, Rwanda, Tanzania and Uganda—for one or two years (2012–13) to collect both quantitative and qualitative data at field and farm level. Average farm yields measured at the eight sites ranged from 1.8 to 4.3 t/ha and the average yield gap ranged from 0.8 to 3.4 t/ha. Across rice-growing environments, major causes for yield variability were straw management, weeding frequency, growth duration of the variety, weed cover, fertilizer (mineral and organic) application frequency, levelling and iron toxicity. Land levelling increased the yield by 0.74 t/ha, bird control increased the yield by 1.44 t/ha, and sub-optimal management of weeds reduced the yield by 3.6 to 4.4 t/ha. There is great potential to reduce the current rice yield gap in ESA, by focusing on improvements of those crop management practices that address the main site-specific causes for sub-optimal yields.     

Spontaneous Renal Tumors Suspected of Being Familial in Sprague-Dawley Rats

Spontaneous renal tubule tumors (RTTs), with a distinctive morphological phenotype, were present in three Sprague-Dawley rats, 1 male and 2 females, out a total of 120 animals of each sex from untreated and placebo control groups in a 2-year carcinogenicity study. One female had one carcinoma, adenoma and hyperplasia, and the other female had five adenomas and many hyperplastic lesions; the male case had one carcinoma. From these cases, a biological continuum of hyperplasia, adenoma and carcinoma could be recognized. The tumors were present in the renal cortex and appeared as solid lobulated growths with occasional central necrosis. The lobules were divided by a small amount of fibrovascular tissue. Occasionally the larger tumors contained a cystic area. Tumor cells appeared distinctive and exhibited variable amounts of eosinophilic/amphophilic and vacuolated cytoplasm. Nuclei were round to oval with a prominent nucleolus. Mitotic figures were uncommon, and no distant metastasis was noted. The tumors were seen as multiple and bilateral lesions in two animals and had no apparent relationship to chronic progressive nephropathy (CPN). Foci of tubule hyperplasia were also noted to contain the same type of cellular morphology. The morphological and biological features of these 3 cases resembled the amphophilic-vacuolar (AV) variant of RTT that has been posited to be of familial origin. This is a report of spontaneous familial renal tumors in Sprague-Dawley rats from Japan.     

Carbon balance in a cool–temperate deciduous forest in northern Japan: seasonal and interannual variations, and environmental controls of its annual balance

We monitored variation in seasonal and annual net ecosystem production (NEP), gross primary production (GPP), and ecosystem respiration (R _E) based on 7-year eddy covariance measurements above a cool?Ctemperate deciduous broad-leaved forest (Japanese beech forest). The 7-year means (±SD) of annual NEP, GPP, and R _E were 312?±?64, 1250?±?62, and 938?±?36?g?C?m^?2?year^?1, respectively. Variation in NEP was much larger than variation in GPP and R _E. During the growing season, the main factor controlling carbon balance was air temperature; variation in seasonal integrated NEP was regulated by accumulated air temperature (degree-day) with a significant negative correlation, whereas the seasonal ratio of R _E to GPP was correlated positively with accumulated air temperature. Because the deviation of seasonal NEP was also significantly correlated with seasonal R _E/GPP, NEP was controlled by R _E/GPP, depending on air temperature during the growing season. Seasonal R _E in the defoliation and snow seasons was also important for evaluating the annual carbon balance, because the total number of days in the two seasons was quite large owing to a long snowy winter. In the defoliation and snow seasons, we found defoliation season length was a major factor determining seasonal integrated R _E, illustrating the positive correlation between R _E and defoliation season length. The major factors controlling interannual variations in forest carbon balance are discussed.     

Investigation on the hydrogen abstraction from methyl glucoside by active oxygen species under oxygen delignification conditions IV: appearance of kinetic isotope effect in the reaction between methyl glucoside and deuterated methyl glucoside

In our previous studies, a clear kinetic isotope effect was observed when a pair of carbohydrate model compounds, methyl ??-d-glucopyranoside (MGP??) and a deuterated MGP?? labeled at the anomeric (methyl ??-d-(1-²H)glucopyranoside) or C-2 position (methyl ??-d-(2-²H)glucopyranoside), was reacted with active oxygen species (AOS) generated by reactions between O₂ and a phenolic compound, 2,4,6-trimethylphenol (TMPh), under oxygen delignification conditions. These results indicate that the AOS abstract the anomeric and C-2 hydrogens of MGP??. Contrarily, no clear kinetic isotope effects were observed when AOS were generated by reactions between O₂ and another phenolic compound, 4-hydroxy-3-methoxybenzyl alcohol (vanillyl alcohol, Valc), and hence, the abstraction of the anomeric and C-2 hydrogens by the AOS was not confirmed. In this study, a pair of MGP?? and the deuterated MGP?? labeled at all the positions, (²H₃)methyl ??-d-(1,2,3,4,5,6,6-²H₇)glucopyranoside, was reacted with AOS generated from TMPh or Valc under oxygen delignification conditions to further examine the appearance of a kinetic isotope effect. A clear kinetic isotope effect was observed when either of TMPh or Valc was the origin of AOS, indicating that some AOS abstract at least a hydrogen of MGP?? in either case. The results are further discussed focusing on the type of AOS generated from TMPh and Valc.     

Root anchorage of hinoki <Emphasis Type="Italic">(Chamaecyparis obtuse</Emphasis> (Sieb. Et Zucc.) Endl.) under the combined loading of wind and rapidly supplied water on soil: analyses based on tree-pulling experiments

Wind damage in Japan is mainly caused by typhoons (i.e., tropical cyclones), which are characterized by intensive heavy rainfall and strong winds. In this study, we conducted tree-pulling experiments on two sites to find out whether rapidly supplied water on the soil would affect stability of root anchorage of hinoki (Chamaecyparis obtuse (Sieb. Et Zucc.) Endl.), as expected. For the experiments, we first supplied several quantities of water around the target trees, and then they were pulled down using a wire winch. On study site 1 (Kamiatago experimental forest), we applied general tree-pulling experiments (no water supply) in 2008 and six different irrigation treatments around the target trees in 2009. On study site 2 (Chiyoda experimental forest), we applied one irrigation treatment in 2009. As a result, five trees were uprooted and two were broken in 2008, and all nine trees were uprooted in 2009 on study site 1, regardless of irrigation treatment. On study site 2, two trees pulled down after 4 h of water supply were ruptured at the stem base, opposite to two trees pulled down immediately after supplying water. The water content below the root plate significantly affected root anchorage and more specifically, the maximum turning moment, stem angle at the maximum force, and stiffness index. Moreover, water inside the root plate increased root anchorage at the beginning of a tree failure process. However, it also reduced the root plate area of the hinge side. Conversely, high water content below the root plate decreased root anchorage.     

Pole and global shape of 25143 Itokawa

The locations of the pole and rotation axis of asteroid 25143 Itokawa were derived from Asteroid Multiband Imaging Camera data on the Hayabusa spacecraft. The retrograde pole orientation had a right ascension of 90.53 degrees and a declination of -66.30 degrees (52000 equinox) or equivalently 128.5 degrees and -89.66 degrees in ecliptic coordinates with a 3.9 degrees margin of error. The surface area is 0.393 square kilometers, the volume is 0.018378 cubic kilometers with a 5% margin of error, and the three axis lengths are 535 meters by 294 meters by 209 meters. The global Itokawa revealed a boomerang-shaped appearance composed of two distinct parts with partly faceted regions and a constricted ring structure.     

Identification of the effects of long-term application of nitrogen fertilizer on the availability of 11 elements in soils and their supply to ‘Jonathan’ apple trees by using simultaneous multi-element analysis

Abstract

The objective of this study was to investigate the effects of long-term application of ammoniacal N fertilizer for 43?years on the availability of 10 essential elements (B, N, Mg, K, Ca, Mn, Fe, Ni, Cu, and Zn) and Al in root-zone soils and their supply to ‘Jonathan’ apple trees. To achieve this objective, we used simultaneous multi-element analysis. To estimate the soil depth from which the apple trees took up these elements, we calculated the ratios of their concentrations in the N fertilized plot (N plot) to those in the no N plot (0?N plot) (N/0N ratio). Long-term N fertilization significantly increased the fruit and leaf N/0N ratios of N and Mn and significantly decreased that of K. These ratios in the fruits and leaves were similar to those in the 20–90?cm soil layer. This result suggests that N, K, and Mn in the fruits and leaves were supplied from the 20–90?cm soil layer. The N/0N ratios of all 11 elements in the fruits and leaves were significantly positively correlated with those in the 20–90?cm soil layer, but not in the 0–20?cm soil layer. Our findings indicate that long-term N fertilization altered the tree nutrition of not only N, but also K and Mn. These changes in the tree nutrition were ascribed to the fertilizer-induced changes in the availability of elements in the subsoils.     

Germination response in wheat grains to dihydroactinidiolide,a germination inhibitor in wheat husks,and related compounds

On the basis of our recent findings that the germination of intact wheat grains with glumes (husks) belonging to dormant varieties was restrained as compared with that of dehusked grains, we have explored the identities of germination inhibitors in the glumes, resulting in the characterization of dihydroactinidiolide (1) and some aromatic compounds. A related natural product, tetrahydroactinidiolide (2), showed similar activity. The present study has demonstrated that the sensitivity in inhibition response of germination of the grains to 1 and 2 declined during after-ripening, in parallel with changes in germinability; the sprouting of after-ripened seeds on a whole spike was preventable by exogenous application of 2 in laboratory conditions, and germination of after-ripened grains was delayed by more than two weeks by the action of 1 or 2. The term "pseudodormancy" is proposed for the phenomenon of delay of germination caused by the inhibitor. After accumulation of additional evidence on inhibition response of actinidiolide-type natural products, structurally related to inhibitor 1, a mechanism concerning germination inhibition by 1 or 2 is proposed on the basis of the concept of nonbonding interaction with the inhibitors at an active site of an acceptor.