Management of Soil Micronutrient Deficiencies in the Rice-Wheat Cropping System

Summary

Within the last three decades, the rice-wheat cropping system has triggered, and with time, aggravated soil micronutrient deficiencies in the Indo-Gangetic Plains (IGP). This has largely been due to the shift from an earlier rice and wheat monoculture with low yielding, long duration indigenous varieties, to an intensive rice-wheat rotation cropping system with short duration modern high yielding varieties on the same piece of land. The problems related to micronutrient deficiency in the IGP are more due to the size of its available pools in the soil rather than its total contents and are greatly influenced by crop management, or rather its mismanagement. Deficiency of zinc is widespread in the IGP, but with the extensive use of zinc sulfate, zinc deficiency has reduced in some areas of the region. Meanwhile, the deficiency of Fe, Mn and B has increased in the IGP. Deficiency of Cu and Mo is location specific and can limit rice and wheat yields. The adoption and spread of the rice-wheat system in permeable coarse textured soils, particularly in the western IGP, not only caused iron deficiency in rice but also resulted in the emergence of manganese deficiency in wheat. In highly calcareous and acidic soils, boron is the next limiting micronutrient in crop production after zinc. Bumper rice and wheat harvests in the past decade, the declining use of organic manures in the region and except for the widespread use of zinc sulfate, a general lack of awareness amongst farmers on micronutrient deficiency problems has contributed to micronutrients limiting rice and wheat yields in the IGP. Approaches to alleviating micronutrient deficiencies include matching the crop removals of the micronutrients with its replenishments through their respective external carriers, supplementation through organic sources and mobilization/utilization through cultivation of micronutrient efficient crop cultivars. Identification of efficient micronutrient carriers and finding the optimum rate, mode and time of its application is important in ameliorating the micronutrient deficiencies. This article reviews the extent of micronutrient deficiency and discusses various management options available to reduce micronutrient deficiency induced crop yield reduction for rice and wheat in the Indo-Gangetic Plains.     

Effects of Micronutrient Deficiencies on Human Health: Its Status in South Asia

SUMMARY

Vitamin A, iodine, and iron deficiencies affect large numbers of people worldwide. A deficiency of one or more of these micronutrients adversely affects the physical and mental abilities of humans. South Asia contains a high percentage of these individuals, not just because of its large population, but also the prevalence of deficiency is higher there than in many other parts of the world. The reasons for the high rates of deficiency in South Asia are many, but they include inadequate availability of micronutrient-rich foods, sub-optimal dietary habits, and high rates of infection. Across the region, national plans vary from (a) increasing availability of appropriate foods, (b) introducing new dietary behaviors, (c) improving health status, and (d) directly addressing deficiency through intervention programs. The extent to which each of the countries is making progress toward the goals of these plans can help in understanding the priorities for future efforts to address micronutrient malnutrition. This article discusses the adverse effects of micronutrient deficiencies in humans with special reference to South Asia.     

Plant Parasitic Nematodes in Rice-Wheat Based Cropping Systems in South Asia

Summary

Rice-wheat based cropping systems in South Asia are among the most highly evolved production systems in the world. The productivity growth of these systems in South Asia is declining due to several factors including the biotic stresses of plant parasitic nema-todes. This article reviews the research on rice and wheat nematodes in a cropping systems perspective and identifies nematodes that have wide host ranges and are greatly influenced by the crop rotations and sequences. These polyphagous nematodes can cause significant damage to rice and (or) wheat crops, either alone or in combination with other microorganisms. The research projects on pest management in the region lack inter-disciplinarity and it is important for nematologists to become integral members of interdisciplinary teams on improving the productivity and sustainability of the rice-wheat cropping systems.     

Weed management in resource conservation production systems in Pakistan

Resource conservation technologies (RCTs) offers pragmatic options to cut down fuel, labor and water resources. In Pakistan, the use of RCTs started in the form of a New Zealand imported zero tillage wheat (ZTW) drill in 1983, and now the ZTW plantation has reached to an area of 507,050 ha. However, initially, the widespread adoption of the ZTW plantation was hampered because of insufficient training and dissemination of information on the proper use of the machinery and planting techniques in Pakistan. In the past few years, rapid uptake of RCTs has been noted in rice-wheat cropping system (RWCS) in Punjab region of Pakistan, the main hub of RCTs, due to direct involvement of farmers during experimentation, and strong collaboration with local machinery manufacturers. In 1992, the inverted ‘T’ openers' technology, was introduced in locally manufactured ZT drills, which helped to make zero tillage (ZT), a user-friendly technology, acceptable at farm level. Now ZT drills equipped with inverted ‘T’ coulter technology are available at cheap and affordable rates. Still many farmers do not have access to RCTs machinery, which requires serious attention of policy makers. After the preliminary experiments on direct seeded aerobic rice (DSAR) in RWCS by rice-wheat consortium and Cereal System Initiative for South Asia, the technology has been widely spread on large area in RWCS in Pakistan in recent years. The other RCTs such as laser land levelling and bed planting of crops are also taking roots in various cropping zones of Pakistan, especially in RWCS. Although, RCTs resolves time and edaphic conflicts, reduces the production cost and save plenty of water; nonetheless weed problem has emerged as serious issues in the adoption of RCTs (especially ZTW, DSAR) in Pakistan. In ZT systems, no preparatory tillage is carried out, which favors the growth of many weeds (e.g., perennial weeds). Likewise, absence of flooding conditions in DSAR favors the growth of many weeds. Change in weed flora from annual to perennial weeds has been observed in ZT systems. However, pre-emergence application of pendimethalin, thiobencarb, butachlor, oxyfluorfen oxadiazon, and nitrofen followed by post-emergence herbicides such as ethoxysulfuron, bispyribac sodium, acetochlor and butachlor provides fair weed control in DSAR in Pakistan. Nonetheless repeated use of herbicides with similar mode of action for managing weeds in ZTW and DSAR in Pakistan may induce herbicide resistance in weeds as has been reported in various parts of the world. In this scenario, the integrated weed management strategies may be useful to control weeds in ZTW and DSAR. The strategies for weed management in DSAR may include the use of stale seedbed technique, use of mulches of allelopathic crops like sorghum, crop rotations with allelopathic crops, intercropping with allelopathic crops, use of allelopathic water extracts, and breeding of competitive crop cultivars. Moreover, strong socio-economic mobilization at farmer fields, extensive research, development, extension and training strategies are required for long term sustainability and tackling the problems of weeds in Pakistan for the rapid uptake of RCTs.     

Application of Micronutrients in Rice-Wheat Cropping System of South Asia

Rice-wheat cropping system(RWCS) is one of the most important cropping systems in South Asia. However, sustainability of this system is under threat owing to several factors, of which deficiency of micronutrients particularly zinc(Zn), boron(B) and manganese(Mn) is one of the major problems. Continuous rotation of rice and wheat, imbalanced fertilizer use and little/no use of micronutrient-enriched fertilizers induce deficiencies of Zn, B and Mn in the RWCS of South Asia. Here we review that(i) imbalanced fertilizer use and organic matter depletion deteriorate soil structure resulting in low efficiency of applied macro-and micro-nutrients in RWCS.(ii) The micronutrients(Zn, B and Mn) are essentially involved in metabolism of rice and wheat plants, including chlorophyll synthesis, photosynthesis, enzyme activation and membrane integrity.(iii) Availability and uptake of Zn, B and Mn from rhizosphere depend on the physico-chemical soil properties(which differ under aerobic and anaerobic conditions) including soil p H, soil organic matter, soil moisture and interaction of these micronutrients with other nutrients.(iv) Plant ability to uptake and utilize the nutrients is affected by several plant factors such as root architecture, root hairs, transport kinetics parameter and root exudates.(v) Crop management and application of these microelements can help correct the micronutrients deficiency and enhance their grain concentration.     

江淮稻-麦周年病虫草害绿色防控技术模式及其效果

江淮地区温光水资源丰富,是我国重要的粮食主产区之一。该地区地处南北气候过度地带,病虫草害类型复杂,病虫草害绿色防控是确保粮食安全生产的重要保障措施。江淮地区作物周年种植,模式多样,其中以稻-麦轮作种植模式为主。本研究根据安徽粮丰项目试验示范成果,结合江淮稻-麦周年生产实际,针对稻-麦周年生长不同生育期主要靶标病虫草害发生规律和为害特点,集成了以农业生态技术措施为前提、绿色防控投入品综合应用为基础、药械联用精准减量高效防控靶标生物技术为突破口的绿色防控技术模式,并成功示范推广。本文就该技术模式进行了详细介绍,以期为区域粮食绿色安全可持续生产提供技术支持。     

Sustainability of the Rice-Wheat Cropping System

Abstract

The rice-wheat cropping system of the Indo-Gangetic Plains (IGP) has contributed tremendously to food security of the region. However, of late there has been a significant slowdown in yield growth rate of this system and the sustainability of this important cropping system is at stake. A decline in soil productivity, particularly of organic C and N, a deterioration in soil physical characteristics, a delay in sowing of wheat, and decreasing water availability are often suggested as the causes of this slowdown in productivity. Therefore, a paradigm shift is required for enhancing the system's productivity and sustainability. Resource-conserving technologies involving zero-or minimum tillage with direct seeding, improved water-use efficiency, innovations in residue management to avoid straw burning, and crop diversification should assist in achieving sustainable productivity and allow farmers to minimize inputs, maximize yields, conserve the natural resource base, reduce risk due to both environmental and economic factors, and increase profitability.     

银合欢遗传资源和育种进展

银合欢为豆科含羞草亚科银合欢属木本植物,现发现22个种,其中18个种为二倍体,4个种为四倍体。银合欢栽培种可作于薪材、木料、造纸、木炭、遮荫和绿肥等,已在澳大利亚、印度、巴拉圭、泰国、中国和其它东南亚国家种植。综述了银合欢的种质收集、评价及分类学研究,分子遗传学研究,种间杂交,增加遗传多样性,抗异木虱育种,耐寒、耐霜和耐旱育种,高产优质牧草育种,优质高产木材育种,不结籽树种育种等。     

长江中下游稻茬小麦超高产群体干物质积累与分配特性

为给长江中下游稻茬小麦超高产(>9 000 kg·hm-2)生产提供理论与实践依据,以中筋小麦新品种扬麦20为材料,通过氮素运筹(氮肥施用量、施用时期和比例)和基本苗调控建立稻茬小麦不同产量水平群体,研究超高产群体干物质积累与分配特性。结果表明,合理调控拔节期至孕穗期及适量增加孕穗期至开花期群体干物质积累量,在开花期干物质积累适量的基础上,重点促进花后干物质积累量,增加成熟期干物质积累量,是长江中下游稻茬小麦实现超高产的关键。稻茬小麦超高产群体开花期干物质积累量为12 800～13 600 kg·hm-2,花后及成熟期干物质积累量分别达7 200、20 000 kg·hm-2以上。开花期群体叶片干物质积累量与花后、成熟期干物质积累量呈抛物线关系,茎鞘、穗干物质积累量与成熟期干物质积累量呈极显著线性正相关,表明开花期叶片干物质积累量达到3 300～3 400 kg·hm-2,茎鞘、穗干物质积累量分别达7 500、2 000 kg·hm-2以上,有利于提高群体花后干物质积累量和产量。     

Development of somaclonal variants of wheat (Triticum aestivum L.) for yield traits and disease resistance suitable for heat stressed and zero-till conditions

In a substantial rice–wheat cropping system area of South Asia, wheat sowing often gets too delayed and exposed to terminal heat stress. Therefore, farmers prefer varieties that are able to perform well under a short growing period. Tissue culturally regenerated plants of wheat variety cv. HUW 234, the most widely cultivated variety of North Eastern Plain Zone (NEPZ) of India were screened using immature embryo as explant. Days to heading and maturity, yield and other yield components and resistance to leaf rust and spot blotch were evaluated. A few somaclones in R₃ and R₄ generations displayed significant earliness for days to heading and maturity, improved yield traits and resistance to leaf rust and spot blotch diseases. The superior performance of two of the variants was confirmed in the R₅ generation in 3 years of testing under two dates of conventional and zero-till sowing. Stability analysis also suggested superiority of the two somaclones across 12 environments. This appeared to confirm the possibility of obtaining useful somaclonal variants of wheat for very late sown as well as zero-till managed agriculture. The superior performing somaclones can be used as parents in the ongoing breeding programmes targeting late sown wheat in South Asia exposed to terminal heat stress.     

Millets, Rice, Social Complexity, and the Spread of Agriculture to the Chengdu Plain and Southwest China

Southwest China played a pivotal role in the spread of agriculture across East and Southeast Asia. Both rice and millet were important in the spread of populations and the expansion of agriculture into this region. Recent finds in the mountainous peripheries of Sichuan Province show that the earliest inhabitants of this region practiced a combination of broomcorn and foxtail millet agriculture (ca 4000?C2500 BC). These crops are adapted to high altitude and arid environments, which facilitated their movement across this region and eventually into the Tibetan Plateau. At around 2700 BC, a combined system of rice and foxtail millet agriculture appears suddenly in sites of the Baodun culture on the Chengdu Plain. The use of this double cropping system provided advantages to the inhabitants of this region in both risk reduction and yield. I argue that this had important consequences for spurring population growth, facilitating expansion into new territories and the development of social complexity.     

Sawah Rice Eco-technology and Actualization of Green Revolution in West Africa： Experience from Nigeria and Ghana

The development and dissemination of sawah rice eco-technology in Nigeria and Ghana as prerequisites for the actualization of green revolution in West Africa were described. It showed that the neglect of the eco-technology and the overemphasis of the biotechnology have rendered the ineffective transferability of the green revolution process from Asia to Africa. The sawah eco-technology increases yield up to 5 t/hm² through bunding and the use of inlet and outlet connecting irrigation and drainage, which enhances effective water control and management, improves the efficiency of fertilizer, improves nitrogen fixation by soil microbes and algae, increases the use of wetlands, improves soil organic matter accumulation, suppresses weed growth, and enhances immune mechanism of rice through nutrient supply. The current experience has therefore established that the technology overcomes the constraints that have limited the realization of green revolution in West Africa.     

江西水稻主产区农户熟制选择行为分析——基于上饶市万年县农户调查的研究

江西是我国双季稻的优势产区,在保障国家粮食安全方面发挥着重要作用。以世界稻作文化发源地之一、古时贡米之乡的江西省万年县为例,通过实地调研和文献资料收集,分析了万年县水稻生产的熟制结构和农户在熟制选择中的考虑因素。结果表明,与近40年江西省水稻种植面积呈现正反“W”型变化特点相似,万年县双季稻呈现先减后增再减的变化特点,而单季稻呈现出持续增加的特点;农户熟制选择受地块特征和地理位置影响较大,城郊和滨湖平原地区的双季稻面积占绝对优势,而丘陵地区的单季稻种植面积在进一步扩大;经济效益和政策因素是农户水稻熟制选择的重要原因,而绿肥种植主要依靠政府政策的引导;劳动力状况和农业生产技术也是农户熟制选择的两大因素。因此,要加强冬闲田的开发利用、恢复绿肥生产、提高复种指数,努力做到土地用养结合、地力常新。调整作物结构、优化种植模式、引导农户遵循“绿色协调发展” 的原则选择合适的种植模式,进行合理的熟制配置,以此构建水稻生产绿色发展结构体系。     

氮肥运筹对不同茬口强筋小麦籽粒产量和品质的影响

为了探讨不同茬口下施氮对强筋小麦籽粒产量和品质的最佳效应,以强筋小麦品种烟农19号为材料,研究了施氮量和追氮时期对不同茬口小麦籽粒产量及品质的影响。结果表明,施氮量和追氮时期对不同茬口下强筋小麦的籽粒产量和品质均有显著的影响。在0～240kg／ha施氮量范围内烟农19号单位面积穗数、每穗粒数和产量随施氮量的增加而显著提高,且旱茬麦产量极显著高于稻茬麦,主要是提高了每穗粒数和千粒重。小麦籽粒蛋白质和面筋含量、沉淀值均随施氮量的增加而显著增加,旱茬麦的品质显著优于稻茬麦。在两种茬口下,烟农19号籽粒产量、蛋白质产量与施氮量均成二次曲线关系,稻茬麦在施氮量为251．26～280．24kg／ha、旱茬麦在施氮量为281．03～303．02kg／ha范围内籽粒产量和蛋白质产量可达到同步提高。拔节期和孕穗期追施氮肥可有效提高单位面积穗数、每穗粒数和产量,且籽粒蛋白质、湿面筋含量和沉淀值显著提高。本试验条件下,旱茬麦在拔节期至孕穗期、稻茬麦在孕穗期追施氮肥可同步提高强筋小麦籽粒产量和品质.     

Integrated crop management of chickpea in environments of Bangladesh prone to Botrytis grey mould

Botrytis grey mould (BGM) is the major constraint to chickpea production in Bangladesh and is considered primarily responsible for that country's recent drastic decrease in chickpea production. There is no substantial host plant resistance to BGM in current chickpea cultivars, but component studies have developed various agronomic options to manage the disease. These include reduced seed rate, delayed sowing and thinning of plants to ensure an open canopy, and need-based foliar application of fungicide. These components were combined with other agronomic requirements for the target region, such as application of phosphate fertilizer, pest management measures against chickpea pod borer, and fungicidal seed treatment against collar rot. The resultant integrated crop management (ICM) package was compared with normal farmer practice (FP) for chickpea cultivation in farmer-managed, operational scale plots at 100 locations across five districts in western Bangladesh in the 2002–2003 and 2003–2004 seasons. Grain yields in ICM plots were generally 15–50% higher than in FP in both seasons. Conduct of these on-farm evaluations in two additional districts in 2004–2005 gave similar results. In 2004–2005, 505 farmer-managed demonstrations were conducted in the five original districts, giving a 5–104% yield advantage (district means) of ICM over FP. In 2005–2006, 642 demonstrations were conducted across the eight districts giving district-wise yield advantages of 27–70%. Effective implementation of BGM management practices by participating farmers demonstrated that remunerative and reliable chickpea yields could be obtained in this BGM-prone environment. The ICM strategy evolved has relevance to other chickpea growing regions prone to BGM in South Asia, Australia and the Americas. Studies are now required on the adoption of components of the ICM package, and the underlying reasons, to identify any adoption constraints and thus guide further promotion of chickpea cultivation.     

Enhancing Productivity of Rice-Wheat System Through Integrated Crop Management in the Eastern-Gangetic Plains of South Asia

Abstract

Rice (Oryza sariva)-wheat (Triticum aestivum) rotation is the major production system in the Indo-Gangetic plains of South Asia and mid hills and is important for the food security of the region. The productivity and profitability of the rice-wheat system are very low mainly because of inappropriate nutrient input and poor crop management practices. Field experiments were conducted in 21 farmers' fields in Bara and Parsa districts in the Eastern-Gangetic plains of Nepal from May 1999 to April 2002 to evaluate site-specific nutrient management (SSNM) and integrated crop management (ICM) for improving rice-wheat productivity and profitability. Soil nutrient-supplying capacity (based on omission plot method) varied largely among farmers' fields. Rice soil had a higher N, P, and K-supplying capacity (35–76, 8–17, and 63–98 kg ha¹, compared with wheat (16–41, 6–12, and 20–104 kg ha¹, respectively). Both SSNM and ICM strategies significantly improved the grain yields of rice and wheat. Overall yield increment by ICM over farmers' practice (FP) reached up to 2.3 Mg ha¹ (66%) in rice and 2.3 Mg ha¹ (87%) in wheat, suggesting that there is a large potential for increasing rice and wheat yields in Nepal. Yield gap 1 (maximum attainable yieldaverage yield in ICM) was 1.3 to 1.4 Mg ha¹ for rice and 0.3 to 1.0 Mg ha¹ for wheat. While yield gap 2 (maximum attainable yieldaverage yield in FP) ranged from 2.8 to 3.5 Mg ha-1 for rice and 2.3 to 2.8 Mg ha-1 for wheat. Rice N-use efficiencies increased up to 50% and 70% with SSNM and ICM, respectively, over FP. In wheat, N-use efficiency increased up to 46% by ICM over SSNM. The net profit gained by applying ICM over FP was higher in wheat (US$ 217) than in rice (US$ 73). The findings suggest the urgent need to develop an effective program for wider dissemination of ICM technology in the Eastern-Gangetic plains.     

Soil Salinity in South India: Problems and Solutions

SUMMARY

Soil salinity is assuming menacing proportions for production of agricultural and horticultural crops in South India. South India comprises of Andhra Pradesh (AP), Tamil Nadu (TN), Karnataka, Kerala, Goa, and Islands in Bay of Bengal (Andaman and Nicobar) and Arabian Sea (Lakshadweep). It comprises central uplands, Deccan plateau (Karnataka plateau and Telangana plateau of AP), Nilgiri hills of TN, South Sahiailri, Eastern hills (Eastern Ghats, TN, upland) and Coastal Plains. The rainfall ranges from 400 to 500 mm in AP, 450 to 1300 mm in Karnataka, 500 to 1215 mm in TN, 100 to 450 mm in Kerala. Climate is mainly semi-arid in nature. Red soils (Alfisols, Inceptisols, and Entisols) make up about 60–65% and are well drained, blacksoils (Vertisols and Inceptisols) comprise about 20–25% and the rest are coastal sands. Soil salinity problems are encountered in almost all the districts in Karnataka and AP. The area extends to about 0.176 million ha in AP, 0.2 million ha in Karnataka, 0.0427 million ha in TN and about 0.03 million ha in Kerala. Introduction of canal irrigation water and use of underground saline waters accelerated the appearance of salt affected soils. Soil salinity observed in South India ranges from hydrometphic saline soils in Kerala to highly saline (EC 20–30 dS m^?1) in Karnataka and AP. Saline soils were classified in to Natrargids or Solarthrids at subgroup level depending on the occurance of nitric or salic horizon within few centimetres of the surface. Soil salinity has reduced crop yields upto 50% and consequently cropping has been abandoned in many areas. Excess soluble salts can be removed through scrapping the surface salt crust or flushing and leaching or through subsurface drainage depending on the problem. Crops also vary in their ability to tolerate salinity at different stages of growth. In most crops subjected to irrigations with saline waters, germination and early seedling stages are generally the most sensitive and their tolerance increases with age. Salt tolerant varieties and nutrient management of crops in saline soils are important solutions for crop production under saline soils.     

Morphological and DNA Barcoding Evidence for Invasive Pest Thrips,Thrips parvispinus (Thripidae: Thysanoptera), Newly Recorded From India

South East Asia pest thrips species, Thrips parvispinus (Karny), is a serious pest on a number of agricultural and horticultural crops in a number of plant families. Based on an integrated approach of morphology and DNA barcoding, invasion of this serious pest is reported first time from India on papaya plantations. Molecular data have corroborated with the morphological identification. Haplotyping data suggested that the Indonesia may be a probable source of invasion of this pest to India.     

Nutritional and Economic Benefits of Enhanced Vegetable Production and Consumption

SUMMARY

Vegetables are a major source of dietary micronutrients, but abiotic and biotic constraints limit vegetable production and consumption in Asia. Per capita vegetable consumption in Asia is far below the required level to satisfy the recommended dietary micronutrient intakes. Empirical evidence and discussion in this article show that enhanced vegetable production and consumption in Asia can play a catalytic role in the overall economic development by improving the nutritional status, learning capabilities and managerial capacities of farmers, generating incomes and jobs in both the farm and non-farm sectors, and improving resource use efficiency in agriculture. Rapid urbanization, higher incomes, and greater awareness amongst consumers and producers to diversify their food and production systems have increased the demand for vegetables in Asia. To realize this potential demand, especially during the off-season of vegetable production, trade-oriented and production enhancement strategies are suggested in this article. The trade-oriented policies can help link the favorable vegetable producing areas with consumption centers, and production oriented policies can overcome the biotic and abiotic constraints of vegetable production by developing economically viable, socially acceptable, and environmentally friendly technologies. Both the strategies require government support and increased allocation of research funds and manpower for vegetable cultivation. Government policies to stabilize vegetable production and trade, can mitigate the risk inherit in vegetable production.     

Maximizing the Nutritional Potential of Potato: the Case of Folate

Micronutrient malnutrition, also known as the hidden hunger, affects over two billion people worldwide. Potato is the third most consumed food crop in the world and is therefore a fundamental element of food security for millions of people. Increasing the amount of micronutrients in potatoes could help alleviate worldwide micronutrient malnutrition. Folate (or vitamin B₉) is an essential micronutrient in the human diet. Deficiencies in folate lead to serious, sometimes lethal, diseases. Unfortunately, folate intake remains suboptimal in both developing and developed regions of the world. This paper uses folate to illustrate various approaches that could be implemented to increase micronutrient content in potato. It provides a brief overview of recent analyses of folate content in diverse potato germplasm, of changes in folate content during tuber development, and of the effect of postharvest low-temperature storage of potato on folate content, and how an optimization of these different factors could lead to significant increases in folate intake from potato.