Increasing Water Productivity in Rice-Based Systems in Asia – Past Trends,Current Problems,and Future Prospects

Abstract

Bioethanol is gathering attention as a countermeasure to global warming and as an alternative energy for gasoline. Meanwhile, due to the synchronous increase in bioethanol production and grain prices, the food-fuel competition has become a public issue. It is necessary to see the issue objectively and to recognize that the real background is the change in allocation of limited resources such as farmland and water. In this review, we discuss which, where and how energy crops shouldbe grown to establish a sustainable bioethanol production system. Several combinations of crops, areas and cultivation methods are recommended as a result of a survey of the bioethanol production system with various energy crops. In tropical and subtropical regions, sugarcane can be grown in agricultural and/or unused favorable lands. In other regions, cellulosic energy crops can be grown in abandoned and marginal lands, including lands contaminated with inorganic pollutant like heavy metals and some detrimental minerals. There also is the possibility that, for Japan and other Asian countries, rice can be grown as an energy crop in unused lowland paddy field. Regarding cultivation way, energy saving is beneficial for bioethanol production systems irrespective of energy efficiency. On the other hand, effective energy input should be consideredfor the systems with higher energy efficiency when available land area is limited. Exploring and developing new energy crops and varieties, which show higher biomass productivity and stress tolerances under marginal conditions, are necessary for sustainable bioethanol production because energy crop production would be restricted mostly to marginal areas in future.     

Potato Research in Africa to Improve Farmers’ Livelihoods: Priorities in Crop Improvement,Seed System,Crop Management,Nutritional Value,Policies and Marketing

The harvested area and production of potato in Sub-Saharan Africa has greatly increased over the last decades. However, yields are still low due to various agronomic, institutional and marketing problems. This paper provides an overview of the most urgent research issues to enhance crop improvement, development of locally adapted, effective seed systems, integrated crop technologies and value chains.     

Yield losses in potatoes,onions and rutabagas in Southwestern Ontario,Canada—the case for pest control

Yield losses in potatoes, onions and rutabagas due to insects, weeds and diseases were measured. In the absence of any pest control, average losses of 64% for potatoes on mineral soil, 85% for potatoes on organic soil, 100% for onions and 88% for rutabagas were recorded. Major single causes of loss were: potato leafhopper, Empoasca fabae (Harris) for potatoes on mineral and organic soil; weeds and early blight, Alternaria solani (Ell. & Mart.) for potatoes on organic soil; weeds, onion maggot, Delia antiqua (Meigen) and leaf blight, Botrytis squamosa (J. C. Walker) for onions; cabbage maggot, Delia radicum (Linnaeus) and weeds for rutabagas. The monetary losses experienced and the cost of each pesticide programme were calculated.     

Retreat of catabolites of filaments,lodicules,and stigma cells in rice

The lodicules expand rapidly when the rice florets are opening, and the filaments elongate and the stigmas extend and bend. All these growing movements are caused by the cell elongation or expansion after water absorption. The lodicules, filaments, and stigma will wither after flowering, but the cause of the withering remains unknown. In some wild abortive male sterile lines, the closing of florets     

Two β-amylase genes,OsBAM2 and OsBAM3, are involved in starch remobilization in rice leaf sheaths

To identify mechanisms of starch degradation in rice leaf sheaths at the post-heading stage, we investigated the function of OsBAM2 and OsBAM3, which encode plastid-targeted active β-amylase isoforms, in starch remobilization in leaf sheaths. The starch content in the second leaf sheaths below the flag leaf (the third leaf sheaths) peaked at the flag leaf emergence stage and gradually decreased until 15 days after heading. The mRNA levels of OsBAM2 and OsBAM3 in the third leaf sheaths increased from the flag leaf emergence stage to the heading stage when the starch content began to decrease. However, these mRNA levels did not always remain high during post-heading. Overexpression of OsBAM2 or OsBAM3 markedly repressed starch accumulation in the third leaf sheaths, showing that OsBAM2 and OsBAM3 function in starch degradation in rice leaf sheaths. In contrast, no significant differences in starch content in the third leaf sheaths were detected between knockdown plants of OsBAM2 or OsBAM3 and non-transgenic wild-type plants. Our results suggest that reduced expression of the individual genes, OsBAM2 or OsBAM3, does not result in excess accumulation of starch in the leaf sheaths, probably because of the complementary function of another gene or the action of other genes encoding starch-degrading .     

Wild potato collecting expedition in Southern Peru (Departments of Apurímac, Arequipa, Cusco, Moquegua Puno, Tacna in 1998: Taxonomy and new genetic resources

Peru has 103 taxa of wild potatoes (species, subspecies, varieties, and forms) according to Hawkes (1990; modified by us by a reduction of species in theSolanum brevicaule complex) and including taxa described by C. Ochoa since 1989. Sixty-nine of these 103 taxa (67% ) were unavailable from any of the world’s genebanks and 85 of them (83%) had less than three germplasm accessions. We conducted a collaborative Peru (INIA), United States (NRSP-6), and International Potato Center (CIP) wild potato (Solanum sect.Petota) collecting expedition in Peru to collect germplasm and gather taxonomic data. This is the first of a series of planned expeditions from 1998–2002. We collected from February 18 to April 18, 1998, in the southern departments of Apurímac, Arequipa, Cusco, Moquegua, Puno, and Tacna. We made 57 germplasm collections, including 14 taxa that are the first available as germplasm for any country (Solanum aymaraesense, S. chillonanum, S. incasicum, S. megistacrolobum subsp.megistacrolobum f. purpureum, S. longiusculus, S. multiflorum,S. pillahuatense, S. sawyeri, S. sandemanii, S. tacnaense, S. tarapatanum, S. urubambae, S. velardei, S. villuspetalum), and two additional taxa that are the first available for Peru but with germplasm from Bolivia (S. megistacrolobum subsp.toralapanum, S. yungasense). Collections also were made for the rare taxaS. acroscopicum, S. buesii, S. limbaniense, andS. santolallae. Our collections suggest the following minimum synonymy may be needed for Peruvian potatoes:S. sawyeri as a synonym ofS. tuberosum;S. hawkesii andS. incasicum as synonyms ofS. raphanifolium;S. multiflorum andS. villuspetalum as synonyms ofS. urubambae.     

Crop performance in permanent raised bed rice–wheat cropping system in Punjab,India

Raised beds are widely used in agriculture in developed countries and have proven to be an excellent option for wheat. Permanent raised beds may also offer benefits for rice–wheat (RW) systems in South Asia, in terms of both production and the possibility that furrow-irrigation may be more efficient than flood irrigation. The performance of a RW system on permanent raised beds (37 cm wide, 15 cm high, furrow width 30 cm) was compared with conventional cultivation on the flat on sandy loam and loam soils in replicated experiments in central Punjab, India. The experiments commenced with wheat sown in November 2002, and were continued for 8 crops.     

Associations between caryopsis dormancy, α-amylase activity,and pre-harvest sprouting in barley

Pre-harvest sprouting (PHS) is a concern for barley (Hordeum vulgare L.) producers, grain processors, and researchers worldwide. Pre-harvest sprouting has been mainly attributed to low dormancy, which is determined by genotype, stage of plant maturation, and environmental conditions during caryopsis development. Fourteen barley genotypes were sown in field experiments at two sites in North Dakota in 2004 and 2005. Spikes were harvested at four different stages: ≈500 g kg⁻¹ moisture content, physiological maturity, harvest maturity, and post-harvest maturity. Results indicated that barley genotypes were released from dormancy at different rates. The 14 barley genotypes were divided into three classes based on their dormancy loss rate during caryopsis development. C93-3230-24 was highly dormant, and ‘Stander’ and ‘Legacy’ were highly susceptible to PHS due to lack of dormancy from as early as 20 d after heading date. All other genotypes fell into the third group that had intermediate dormancy loss rate. No significant correlation was detected between barley α-amylase activity and germination percentage. A moderate association between malt α-amylase activity and caryopsis dormancy suggested that cultivars with increased malt α-amylase activity tend to have low dormancy and may be more prone to PHS.     

A sesquiterpene quinone, 5-Epi-smenospongine, promotes TNF-α production in LPS-stimulated RAW 264.7 Cells

Eight sesquiterpene quinones: ilimaquinone (1), smenospongidine (3), smenospongiarine (5), smenospongine (7), and their corresponding 5-epimers 2, 4, 6, and 8, isolated from the Palauan marine sponge Hippospongia sp., were examined regarding their effects on TNF-α production in LPS-stimulated RAW 264.7 cells. 5-Epi-smenospongine (8) promoted the production of TNF-α to a level three times greater than the control at 10 μM, but compounds 1–7 did not show apparent activity. The results suggest that the cis-decaline ring and a primary amine in the benzoquinone ring are necessary for activity. This is the first study to report the modulation of TNF-α production by a sesquiterpene quinone.     

Booms, Busts, and Emerging Markets for Potatoes in East and Central Africa 1961–2010

Potato production expanded more rapidly in Africa than in any other region of the world in recent years. This paper examines that phenomenon by focusing on the evolution of potato production, utilization, and trade in East and Central Africa. Based on an analysis of the Food and Agriculture Organization of the United Nations annual secondary data over nearly the last 50 years complemented by a review of the literature, the findings note that the long-term upward trends in production and area harvested contrast with the sharp decline in the growth rates for output, area, and yields over the last decade. In recent years, output grew rapidly in some countries and declined in others. Emerging markets include fresh potatoes as well as French fries and crisps for the growing number of urban consumers and improved quality seed. The paper concludes with a series of policy recommendations aimed at catalyzing improvements in productivity and marketing as well as capitalizing on opportunities for industry.     

More Rice,Less Water—Integrated Approaches for Increasing Water Productivity in Irrigated Rice-Based Systems in Asia

Abstract

The water crisis is threatening the sustainability of the irrigated rice system and food security in Asia. Our challenge is to develop novel technologies and production systems that allow rice production to be maintained or increased in the face of declining water availability. This paper introduces principles that govern technologies and systems for reducing water inputs and increasing water productivity, and assesses the opportunities of such technologies and systems at spatial scale levels from plant to field, to irrigation system, and to agro-ecological zones. We concluded that, while increasing the productivity of irrigated rice with transpired water may require breakthroughs in breeding, many technologies can reduce water inputs at the field level and increase field-level water productivity with respect to irrigation and total water inputs. Most of them, however, come at the cost of decreased yield. More rice with less water can only be achieved when water management is integrated with (i) germplasm selection and other crop and resource management practices to increase yield, and (ii) system-level management such that the water saved at the field level is used more effectively to irrigate previously un-irrigated or low-productivity lands. The amount of water that can be saved at the system level could be far less than assumed from computations of field-level water savings because there is already a high degree of recycling and conjunctive use of water in many rice areas. The impact of reducing water inputs for rice production on weeds, nutrients, sustainability, and environmental services of rice ecosystems warrants further investigation.     

Long range migration of rice planthoppers and associated meteorological conditions in Yulin,Ganzhou,and Huangyan

In recent years ,it has been demonstrated that the low-level jet streams (LLJs) developed in the south of the Meiyu(Baiu) front play a critical role in the overseas migrations of the planthoppers into Japan and Korea. However, the involement of the LLJs during the process of sequential displacements of rice planthoppers in China has not been clarified yet. In the present studies, the synoptic meteorological factors including LLJs associated with the     

Distribution and function of LMW glutenins,HMW glutenins,and gliadins in wheat doughs analyzed with ‘in situ’ detection and quantitative imaging techniques

The different gluten subunits, gliadins, LMW glutenins, and HMW glutenins have been reported to play different key roles in different type of wheat products. This paper studied the interaction between gliadin, LMW and HMW glutenins in soft, hard and durum semolina flour doughs during different stages of mixing. In order to see how do the gluten subunits (gliadin, LMW glutenin and HMW glutenin) redistribute during mixing, dough samples were taken at maximum strength and 10 min after maximum strength. The doughs have been mixed with the same level of added water (55%), therefore they all have different strengths values due to their changes in proteins content. Oscillatory rheological measurements were performed on the doughs. It has been found that HMW glutenins are relatively immobile because of their less molecular mobility and do no redistribute themselves especially at high strength for doughs such as hard wheat flour. LMW glutenins and gliadins on the other hand redistribute themselves at even at high dough strengths forming a more stable network. In weaker doughs such as soft wheat, the breakdown of the three proteins subunits is responsible for the decay in dough strength. We have also visualized how the greater amount of LMW glutenins in semolina is in constant interaction with HMW glutenins and gliadins allowing the dough to maintain a stable strength for an extended mixing time. Finally, we have found the ‘in situ’ detection and quantitative analysis techniques to be more sensitive to the changes occurring in the gluten network of the dough than the oscillatory rheological analysis.     

Effects of Different Nitrogen Fertilizer Levels on Fe, Mn, Cu and Zn Concentrations in Shoot and Grain Quality in Rice （Oryza sativa）

In a pot experiment, effects of N fertilizer application on the concentrations of Fe, Mn, Cu and Zn in shoot of rice and the quality of brown rice were studied. In the treatments with N fertilizer application, the concentrations of Fe, Mn, Cu and Zn in most parts of rice shoot increased compared with control (no N fertilizer application). This indicated that the transportation ability of microelements from root to shoot in rice was improved with N fertilizer application. Effect of N fertilizer on IR68144 was similar to that of on IR64, but the concentrations of the microelements in plant differed, suggesting that the characteristic expression of the two rice genotypes was not controlled by the amount of N fertilizer supplied. The concentrations of those microelements in brown rice increased at first and then decreased with increasing N fertilizer application, reaching the highest at 160 kg/ha, at which the Fe, Mn, Cu and Zn concentrations in brown rice increased by 28.96%, 41.34%, 58.31% and 16.0% for IR64, and by 22.16%, 13.75%, 8.75% and 20.21% for IR68144 compared with control, respectively. Moreover, N fertilizer promoted the accumulation of protein, decreased the accumulation of amylose in grain, and enhanced gel consistency of brown rice. These results indicate that appropriate N fertilizer management could increase micronutrient contents in grain and improve nutrition quality of rice.     

Sweet Potato Weevil Damage,Production Constraints,and Variety Preferences in Western Tanzania: Farmers’ Perception

Sweet potato weevils (Cylas spp.) are among the most important constraints to sweet potato (Ipomoea batatas [L.] Lam.) production in most agro-ecological zones of Tanzania. Integration of farmers’ perception on sweet potato weevil damage, production constraints, and variety preferences is crucial in developing sweet potato varieties with farmer-preferred traits and weevil resistance. The aim of this study was to identify farmers’ perceptions on sweet potato weevil damage, production constraints, postharvest storage options, and criteria used to select and grow the best sweet potato varieties in western Tanzania. Surveys were conducted in four selected districts of western Tanzania (Nzega, Sikonge, Kigoma rural, and Kasulu) known for sweet potato production. Data were collected using a structured questionnaire, focus group discussions (FGDs), and transect walk involving 122 sweet potato farmers. Weevil damage was reported by 84% of the respondents to be the overriding constraint to sweet potato production. Sweet potato diseases and drought were the next production constraints, reported by 57% and 54% of the respondents, respectively. Farmers’ preferred agronomic traits of sweet potato included high yield (25% of respondents), drought tolerance (24%), and disease and pest resistance (21%). Farmers’ preferred sweet potato culinary traits in the study areas were high dry matter content (reported by 21% of the respondents), followed by reduced cooking time, taste and fiber content (each reported by 19% of the respondents). The above-mentioned production constraints and farmers’ preferred traits are useful selection criteria for improving sweet potato with respect to weevil resistance and enhanced storage-root yield and quality.