インドネシアジャワ島南央部における高地の天水農業の収量とグローバル指数との関係について

Although there has been a high interest to investigate the relationship between climate and crop yields in Indonesia, little evidence is available for crops in highland of the country. This study evaluates the relationships between global climate indices (Southern Oscillation Index, SOI; sea surface temperature, SST) and rain-fed crop yields in Gunungkidul district, highland of South-Central Java. Principal Component Analysis (PCA) approach was used to summarize the averaged SSTs during planting season for the El Nino monitoring regions: IOBW (Indian Ocean Basin-Wide), Nino.West and Niiio.3. Crops yield of each sub-district of the area was detrended using a 5-year moving average to enhance reliability of the data. For some sub-districts, the first principal component of SSTs was negatively correlated to crop yield residuals of corn and soybean while SOI was positively correlated to that of corn and dryland paddy.インドネシアにおいては気候と農作物収量との関係に高い関心が寄せられているが，高地農業に関しては進展が少ない状況である。本研究では，南方振動指数（SOI）および海水面温度（SST）のグローバル指数とジャワ島南央部に位置するグヌンキドウール地区における天水農作物収量との関係を分析した。３つの地域（IOBW, Niňo.ＷestおよびNiňo.3）のＳＳＴに対して主成分分折（PCA）を適用し，その代表となる主成分を抽出した。各地域の作物収量データの信頼性を向上させるために，元の収量データとその５年移動平均値から残差を計算し，正規化した。いくつかの地域では，SSTの第１主成分とトウモロコシ・ダイズの残差との間に負の相関を示し，またSOIはトウモロコシ・陸稲の残差との間に正の相関を示すことが明らかとなった

Genotypic differences in soybean yield responses to increasing temperature in a cool climate are related to maturity group

To adapt soybean production to climate change, a thorough understanding of its response to high temperature is required. Modeling studies have predicted that high temperature would shorten the growth period and hence lower seed yield of less day length-sensitive (early-maturing) soybean cultivars, whereas the magnitude of yield reduction by high temperature would be smaller in cultivars with higher day length sensitivity (late-maturing), suggesting that late-maturing cultivars would benefit from a future high-temperature environment. Current mean growing season temperature ranges from 19.4 to 22.6 degrees C in the northern, cool regions of Japan, which is near or below the reported optimum temperature (22-24 degrees C) for seed yield. We tested the hypothesis that adaptation by growing late-maturing cultivars will be successful in maintaining seed yield under a cool climate when temperature is increased during 21st century. We used three Japanese soybean cultivars, early-maturing Yukihomare and late-maturing cultivars Ryuhou and Enrei. Plants were grown over 3 years from June to September (a conventional season) under three temperature regimes, T1 (ambient), T2 (1.8-3.6 degrees C above ambient), T3 (4.8-5.7 degrees C above ambient), in a sunlit temperature gradient chamber. The leaf area at the full expansion stage, pod and seed numbers, and seed yield increased at elevated temperature in the late-maturing cultivars but not in the early-maturing one. The photosynthetic rate and effective quantum yield of photosystem II at the flowering stage increased at elevated temperature in all three cultivars. The period from sowing to the beginning of flowering (R1) decreased in all three cultivars at elevated temperature, whereas the period from R1 to the beginning of pod addition and the flowering period were prolonged in the late-maturing cultivars, but not in the early-maturing one. The differential response in post-flowering development in different maturity groups is probably related to the differences in the day length requirements of these cultivars. Our data clearly demonstrate that yield enhancement by increasing temperature in the late-maturing cultivars resulted from both the improvement in sources (leaf area and leaf photosynthesis) and the increase in sink size (number of flowers, pods and seeds) due to the longer flowering period. We conclude that the yield of the late-maturing cultivars sown during the conventional season in the cool regions of Japan will increase during the 21st century. (C) 2014 Elsevier B.V. All rights reserved

Creation and application of 250 m square grid meteorological information for crop management using a local weather station network

A method to estimate meteorological factors on a 250 m square grid using real-time data from a local weather station network was developed. The method had better precision than an existing one. The 250 m square grid meteorological information was created to cover Memuro City, Hokkaido. The informa - tion was used with a wheat developmental model to predict the distribution of wheat maturity days in the city, which had 6, 170 ha of wheat fields and 50 combine harvesters, to support decisions for the best management of the harvesters to avoid damage by preharvest sprouting