Arbuscular mycorrhizal fungi (AMF) are ecologically important members of the soil microbial community. The AMF status of Curcuma aromatica and C. longa growing in different soil types (Shimajiri–Maji, Jagaru and Kunigami–Maji), on the main island of Okinawa, Japan, was assessed by investigating AMF colonization rate, AMF spore density, and relative abundance of AMF by fatty acid analysis in September 2010 and November 2011. AMF were also identified by SSU rRNA gene sequencing from roots in 2011. AMF colonization ranged from 4.1-63.9% in 2010 and 1.3-51.9% in 2011. Curcuma plants cultivated in Kunigami–Maji showed a significantly lower AMF colonization rate, compared with other soils in 2011. The AMF spore density in soil was higher in Shimajiri–Maji and Jagaru, compared with Kunigami–Maji in 2011. Stepwise linear regression model with soil properties such as pH, EC, soil N concentration (mineral N or nitrate N) and available P concentration (Truog-P) for AMF status suggested that available P negatively, pH positively correlated to the AMF colonization rate or AMF spore density in both years. In total, 9 AMF phylotypes were identified by sequencing. The phylogenetic analysis showed that most of the identified AMF belonged to the genus Glomus group A. A few clones representing phylotypes belonging to Acaulosporaceae, Diversisporaceae and Glomus B group were amplified from some roots. These results could be important for the understanding of indigenous mycorrhizal symbiosis and the management of soil ecosystems in Curcuma plants on the main island of Okinawa.
Fipronil bait (0.5% active ingredient, Prince®, BASF Agro) is a recently introduced insecticide for wireworms. We examined its effects on the growth and yield of sugarcane during spring cropping and ratoon cropping, on Kume Island, Okinawa, Japan. During spring cropping, fipronil bait significantly lowered the number of dead heart stalks in comparison with a more conventional insecticide against wireworms, ethylthiodemeton granules (3.0% active ingredient, TD®, Sankyou Agro). The number of damaged buds and the damage rate were significantly lower, and the number of stalks and the sugarcane yield were significantly higher in fipronil-baited areas than in untreated areas. During ratoon cropping, however, these effects were not detected, and insect damage reappeared. We conclude that fipronil bait treatment during planting increases sugarcane yield but, following ratoon cropping, it is necessary to re-treat with fipronil bait or other insecticides to prevent a recurrence of insect damage.
This paper discusses the amount of maize seed required per unit area and the spacing formed using the Ethiopian traditional plow -maresha-, based on data obtained from randomly selected smallholder maize growers. The results showed that farmers planted 64% and 180% higher amounts of seed in row-planting and broadcasting, respectively than the research-recommended seed rate per hectare for maize. The maresha plow opens a 50 cm spacing between rows, compared to the recommended 75 cm. It was found that the value of the seed saved by adopting row-planting exceeded the value of hiring labor for row-planting at peak time to solve household farm labor shortage. Thus, the recommended maize row spacing and seed rate should be reconsidered in line with farmers’ plow used in maize planting.
Within an oil palm field, different micro sites are established for fertilizer application (weeded circle), organic matter addition (frond heap) and operation paths (harvest path). This study reports the soil characteristics on an oil palm field with special reference to the micro sites as well as slope positions. For this study purpose, a second generation oil palm field (average slope gradient of 8°) with 10 years old oil palm was selected. The soils (Typic Hapludox) could be generally characterized by acidic nature and low levels in exchangeable bases with high aluminum activity. Soil properties were significantly or tended to be different at the depth of 0-5 cm and 5-10 cm in terms of micro sites; total carbon (T-C), total nitrogen (T-N), exchangeable magnesium (Mg) and exchangeable calcium (Ca) contents were higher at the frond heap. On the other hand, higher amounts of available phosphorus were accumulated in the weeded circle due to fertilizer application. Meanwhile, between different slope positions, non-distinct soil particles movement was observed and no evidence of soil erosion was found.
A triple-rice-cropping system is widespread in the Mekong Delta, and not only are 21 million tons of rough rice (in 2008) produced annually but also 24 million tons of straw mass (dry weight) are estimated to be generated annually. The management of this straw has the potential to influence sustainable agronomic productivity of the region as well as global warming. This study was conducted to understand the present management of rice straw in the system.In a typical triple-rice-cropping system in Can Tho, Viet Nam, located in the centre of the Mekong Delta, interview surveys of 50-household farmers on their uses of straw in 2007-2011 and 35-household farmers on their uses of straw and yields of rice grain and straw from September 2011 to November 2012 were conducted. Almost all (100%) of the straw harvested in the winter-spring cropping seasons was burned. However, the incineration ratios of subsequent cropping seasons (spring-summer and summer-autumn) decreased to 22% and 1%, respectively. The incineration ratios of harvested straw tended to become lower when the precipitation was high at harvest time. Most of the straw that was not burned was removed from the paddies and was utilised as mushroom beds (69% in spring-summer and 71% in summer-autumn).Thus, the use of rice straw seems to be passive in the area at present, i.e., the farmers burn the straw when it can be burned easily; however, to enhance the region’s sustainable agronomic productivity, there must be further study on the use of the straw that is currently burned.
Curcumin yield, rhizome yield and curcumin content in Curcuma species and strains collected from Japan and Southeast Asian countries were compared, and these relationships were analysed based on the three previously proposed genetic groups: Japanese and Southeast Asian C. longa (Group 1), Southeast Asian C. longa (Group 2), and C. aromatica and other C. species (Group 3). Group 1 had a medium curcumin content with a high rhizome yield; Group 2 had a high curcumin content with a low rhizome yield; and Group 3 had a low curcumin content with a high or medium rhizome yield. Multiple regression analysis indicated that the differences in curcumin yield among species and strains were mainly determined by their curcumin content. However, the main factor determining curcumin yield was different in each group: the rhizome yield in Group 2, the curcumin content in Group 3, and both rhizome yield and curcumin content in Group 1. The differences in curcumin yield found in this study are well explained by their grouping based on genetic analysis.
The dominant features of the Myanmar Dry Zone include erratic rainfall, soil with low nutrient content and high temperatures. The majority of the people depend on agriculture. In order to determine how the local people adapted themselves to their agro-environment, land types and agricultural systems in four villages in the Sagaing region were analyzed, based on field observations and interviews. In the surveyed villages, a sesame-pigeon pea intercropping system has predominated since long time ago. Other upland field crops such as groundnut and a fruit tree, jujube, were also cultivated. Groundnut and sesame oil mainly fulfilled home consumption. Pigeon pea and jujube were cash crops exported to India and China. The existing cropping systems were able to secure their home consumption with adaptability to the environment, in addition to supply of the income. In the recent decades, however, the farmers have faced a reduction in the productivities of the present major crops. They are considering the possibility of introducing more profitable new cash crops than those in the present cropping systems to provide a higher economic viability.