Eiji Nawata

Alterations in photosynthesis and some antioxidant enzymatic activities of mungbean subjected to waterlogging

Abstract Photosynthetic rate ( P ), leaf water potential ( ψ L ) and chlorophyll fluorescence were studied in mungbean plants subjected to waterlogging in a plastic greenhouse, and leaf samples were collected for the analysis of enzymes involved in anti-oxidant photoprotection. Waterlogging caused a fast decline in the photosynthetic rate and water use efficiency without changes of transpiration rate and stomatal conductance during the early waterlogging period, which indicates that reduction of photosynthetic rate might be due to a mechanism independent from stomatal closure. Early reduction of Fv/Fm value of chlorophyll fluorescence by waterlogging indicates that the early reduction of photosynthetic rate is correlated with photo inhibition of photosystem II (PSII). Stomatal conductance and water use efficiency was decreased progressively during prolonged waterlogging while ψ L was unchanged, indicating stomatal closure without water stress. The activities of active oxygen processing enzymes, such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) decreased during prolonged waterlogging indicating no evidence of oxidative stress and/or damage in leaves of mungbean by waterlogging. Our results suggest that oxidative damage is not directly involved in damage to the photosynthetic machinery during waterlogging in mungbean plants.

Capsicum frutescens L. in Southeast and East Asia, and its dispersal routes into Japan

Isozyme analyses were conducted to study the geographic variation ofCapsicum frutescens L. in Southeast and East Asia, and to investigate its dispersal routes into Japan. Eight enzymes (EST, EM, G6PD, GR, ME(A), PGI, PGM, ShDH) were variable among accessions ofC. frutescens in Southeast and East Asia. Accessions from the Ryukyu Islands were closely related to those in Indonesia, whereas accessions from the Bonin Islands showed exactly the same isozyme patterns as those from Indonesia and Northern Thailand. Accessions in the Ryukyu Islands were different from those in the Bonin Islands, suggesting that there may be two independent dispersal routes into Japan. One route was from Indonesia via the Philippines or Taiwan, or directly to the Ryukyu Islands, and another was from Indonesia via the Mariana Islands, or other islands in the Pacific, to the Bonin Islands.

A split-root apparatus for examining the effects of hydraulic lift by trees on the water status of neighbouring crops

We describe a split-root system for examining the effects of hydraulic lift by trees on crop growth. In this system, upper lateral tree roots were grown in a container set on the ground through which the taproot of the tree could penetrate into the moist soil below. The container, with a radius of 0.5 m and a height of 0.20 m, consisted of two compartments divided by a waterproof barrier. A markhamia tree (Markhamia lutea (Benth.) Schumann) and upland rice (Oryza sativa (L.)) plants were planted in one compartment, with only rice plants planted in the other compartment. Irrigation of the container was ceased at the start of the experiment. The stomatal conductance of the rice plants in the associated side, in which both trees and rice plants were grown, declined more rapidly during the first drying period than in the rice-only compartment, suggesting that there was competition for water between the tree and the crop plants. However, during the later drying period, the rice plants in the associated side were green and viable, while those in the rice-only side became desiccated. Rice roots were seen intermingling with tree roots, and the soil water content in the associated site tended to be higher than in the rice-only side. It is likely that hydraulic lift occurred in the associated side and that water that had been transferred to the surface roots was released into the soil, enabling the rice plants in this compartment to remain viable. This novel system is useful for examination of the effects of hydraulic lift by trees on the growth of neighbouring crops.

Effects of Waterlogging at Vegetative and Reproductive Growth Stages on Photosynthesis, Leaf Water Potential and Yield in Mungbean

Abstract The effects of short-term waterlogging on mungbean and recovery from the damage were studied in a plastic greenhouse. Pot-grown plants of two mungbean cultivars, KPS1 and CNXP-49 were waterlogged for eight days, at the vegetative and reproductive growth stages. Photosynthetic rate (P), transpiration rate (Tr), diffusive resistance (rs) and leaf water potential (Ψl) were measured at the 1st, 4th and 8th day of the 8-day waterlogging treatment and at the 4th and 8th day after the end of waterlogging. P was reduced significantly by waterlogging. It was reduced by 58 and 64% at the 8th day of waterlogging at the vegetative and reproductive stages, respectively, in KPS1 and, by 76 and 82%, respectively, in CNXP-49. Tr was reduced by 48 and 66% in KPS1 and CNXP-49 respectively, at the 8th day of waterlogging at both stages. The diffusive resistance at the 8th day of waterlogging was increased by 79 and 83%, in KPS1 and CNXP-49, respectively, at the vegetative stage, and by 76 and 79% at the reproductive stage. All these physiological parameters of both cultivars recovered to almost normal values within 4 days after the end of waterlogging at the reproductive stage and within 8 days at the vegetative stage. Waterlogging did not affect Ψl, indicating that the decrease in P and Tr was not associated with leaf dehydration. Waterlogging at the vegetative and reproductive stages significantly reduced the dry matter accumulation during and after the waterlogging in both KPS1 and CNXP-49. Final seed yield in KPS1 and CNXP-49 was reduced by 16 and 19%, respectively, by the waterlogging at the vegetative stage and by 23 and 30%, respectively, by that at the reproductive stage. Although even short-term waterlogging markedly affected P, Tr and rs of mungbean, the damage particularly in P and leaf growth was quickly recovered after the end of waterlogging and the reduction of seed yield was less than that expected from the damage in the physiological characteristics. These results, suggest that mungbean has an ability to recover from the short-term waterlogging damage and that the response to waterlogging varies with the cultivar.

Use of Capsicum frutescens L. by the Indigenous Peoples of Taiwan and the Batanes Islands

Use of Capsicum frutescens L. by the Indigenous Peoples of Taiwan and the Batanes Islands. The local nomenclature, use, and distribution of C. frutescens among indigenous peoples in Taiwan and the Batanes Islands were studied. Among Taiwanese indigenous peoples, the distribution, frequency of use, and importance of C. frutescens were found to increase with decreasing latitude, which appears to have affected the local names of Capsicum and C. frutescens. The local name for Capsicum in the Batanes Islands—“sili”—is used by several indigenous peoples in Taiwan, suggesting that Capsicum was brought from the south to the north. Indigenous peoples in Taiwan and the Batanes Islands used C. frutescens fruits as condiments, medicines, ornaments, or for ritual uses; also, they used its leaves for soup. A complex of both green and yellowish-green types possessing ShDH-B was introduced from Indonesia into the Batanes Islands and Taiwan, and later only the type with yellowish-green immature fruit was introduced to the Ryukyu Islands under the bottleneck effect.

A Model for Phenological Development of Vietnamese Rice Influenced by Transplanting Shock

Abstract Phasic development of rice is influenced by various climatic conditions and the nursery duration. As a step toward the analysis of yield potential and yield loss in the Red River Delta, Vietnam, we conducted field trials with different nursery durations and transplanting times to develop a model for estimating heading times of a non-photosensitive cultivar CR203 in the Red River Delta. Days from seedling emergence to heading varied from 73 to 106 d, the rainy season crops having a shorter duration than the winter-spring season crops. The heading time could generally be estimated by the function of air temperature, but the delay in heading due to transplanting (transplanting shock), defined as the difference in the days from emergence to heading between transplanted and direct-seeded rice, ranged from 1 to 9 d and caused a substantial error in the heading time estimation. This variation in the delay of heading was explained as a function of the seedling age at the transplanting time. The model considering the transplanting shock estimated the heading dates in the independent data sets obtained at fields of local farmers with root mean square deviation (RMSD) of 2.15, while the model not considering the transplanting shock estimated those with a RMSD of 3.34. We conclude that this simple transplanting shock model was applicable for estimating the rice phasic development in the Red River Delta.

Capsicum Use in Cambodia: The Continental Region of Southeast Asia Is Not Related to the Dispersal Route of C. frutescens in the Ryukyu Islands

CapsicumUse in Cambodia: The Continental Region of Southeast Asia Is Not Related to the Dispersal Route ofC. frutescensin the Ryukyu Islands. The local nomenclature and use of Capsicum by Khmer and other ethnic groups in Cambodia and the distribution of the diagnostic ShDH-B isozyme pattern of C. frutescens were studied. People in Cambodia use Capsicum in various ways, not only as a condiment but also as a vegetable, a medicine, and a colorant, and in popular beliefs, agricultural rituals, taboos, and rice malt. The findings showed that the ShDH-B phenotype may not have occurred as a mutation in Asia but in the Americas and then was introduced to Asia. Also, the ShDH-B phenotype is distributed in the insular regions of Southeast and East Asia and Oceania, but seems not to be distributed in the continental region of Southeast Asia. One possible hypothesis is that C. frutescens possessing the ShDH-B phenotype was introduced directly from the Americas via Oceania to the Philippines, and it thereafter dispersed into the insular regions.カンボジアにおけるトウガラシ属の呼称・利用・分布 - 特にキダチトウガラシの伝播に着目して - . これまでの研究から, 南西諸島のキダチトウガラシは東南アジアでは稀有なアイソザイム型 (シキミ酸脱水素酵素B型, ShDH-B) を持つことが明らかとなっている. ShDH-Bは台湾・フィリピンのバタン諸島・ジャワ島には分布するが, 東南アジア大陸部 (タイ・ラオス・ベトナム) ではその分布が現在のところ確認されていない. 伝播経路の推定精度を向上させるためには, 東南アジア大陸部におけるShDH-Bの分布を精査する必要があるが, カンボジアにおけるトウガラシ属の情報および収集されたキダチトウガラシの系統がこれまでになかった. そこで, カンボジアにおけるトウガラシ属の呼称・利用およびキダチトウガラシのShDH-Bの分布を検討した. カンボジアでは, トウガラシ属は香辛料だけではなく野菜 (果実・葉) や薬, 着色料, 俗信, 農耕儀礼, 禁忌, 麹の材料や酒文化における儀礼に利用されていた. また, カンボジアを含めて世界で収集したキダチトウガラシ316系統を用いてアイソザイム分析をおこなったところ, 新大陸の系統がShDH-Bを示したことから, ShDH-Bは変異などによってアジアで発生したわけではないと考えられた. また, バヌアツにShDH-Bを示す系統が存在したことから, 南西諸島系統が島嶼部のみを経由して伝播した可能性が一層強まった. ShDH-Bが東南アジア大陸部に分布しないこと, そして16世紀中葉から19世紀初頭かけてフィリピンのマニラとメキシコのアカプルコとの間でガレオン貿易がおこなわれていたことを考慮すると, ShDH-Bを示すキダチトウガラシは新大陸から直接太平洋を経由してアジアに伝播した可能性がある.

Effects of waterlogging duration on the growth and yield of yard long bean (Vigna sinensis var. sesquipedalis)

Abstract After being waterlogged in sterilized soils for only 4 days, yard long bean plants and roots recovered rapidly, and their yield was not reduced significantly. The plants could adapt themselves to prolonged waterlogging and resumed vigorous development after a brief retardation of growth. Their yield was comparable with that of non-waterlogged plants. These facts suggest that yard long bean is rather tolerant of the direct effect of waterloggin, soil oxygen deficiency. When waterlogging was terminated after the completion of the adaptation, post-stress growth was retarded and the yield was reduced significantly. This indicates that waterlogged plants are subjected to a dual stress, with a first stress of soil anaerobiosis and a second stress associated with the removal of waterlogging.

Geographical distribution of ribosomal DNA variation in taro, Colocasia esculenta (L.) Schott, in eastern Asia

Restriction fragment length polymorphism (RFLP) at the ribosomal RNA gene loci (rDNA) was investigated in 227 accessions of taro, Colocasia esculenta (L.) Schott, from China, Japan, Taiwan, and Vietnam. Eighteen different restriction fragment patterns of rDNA were observed. The results were largely consistent with a previous classification based on isozyme data. Some rDNA patterns were distributed extensively in the temperate zone from inland China to Japan. On the other hand, some other patterns ranged in coastal and/or insular areas from the tropical zone to the temperate zone (Japan). These geographical distributions may suggest two different routes for the introduction of taro into Japan: one from China,and the other most likely from Southeast Asia, via Taiwan and the Ryukyu Islands (southern Japan).

Effects of CCC on the occurrence of tomato puffy fruits and the endogenous cytokinin activities

Abstract CCC treatment at flowering time suppressed the occurrence of tomato fruit puffiness in solution culture. Root application, truss spraying and whole plant spraying of CCC were all effective in correcting fruit puffiness, and truss spraying did not decrease fruit weight, unlike the other two treatments. For practical use, truss spraying might be the best method to control tomato fruit puffiness. Cytokinin contents in the xylem sap of tomatoes increased when CCC was applied to roots. This suggests that cytokinin biosynthesis in roots was increased by CCC treatment. Cytokinin activities in tomato fruits at an early developmental stage were also markedly increased by CCC treatment to roots. These results suggest that the CCC effect on the control of tomato fruit puffiness might be partly due to increased cytokinin activity in the developing fruit.