Nitrate paradigm does not hold up for sugarcane

Modern agriculture is based on the notion that nitrate is the main source of nitrogen (N) for crops, but nitrate is also the most mobile form of N and easily lost from soil. Efficient acquisition of nitrate by crops is therefore a prerequisite for avoiding off-site N pollution. Sugarcane is considered the most suitable tropical crop for biofuel production, but surprisingly high N fertilizer applications in main producer countries raise doubt about the sustainability of production and are at odds with a carbon-based crop. Examining reasons for the inefficient use of N fertilizer, we hypothesized that sugarcane resembles other giant tropical grasses which inhibit the production of nitrate in soil and differ from related grain crops with a confirmed ability to use nitrate. The results of our study support the hypothesis that N-replete sugarcane and ancestral species in the Andropogoneae supertribe strongly prefer ammonium over nitrate. Sugarcane differs from grain crops, sorghum and maize, which acquired both N sources equally well, while giant grass, Erianthus, displayed an intermediate ability to use nitrate. We conclude that discrimination against nitrate and a low capacity to store nitrate in shoots prevents commercial sugarcane varieties from taking advantage of the high nitrate concentrations in fertilized soils in the first three months of the growing season, leaving nitrate vulnerable to loss. Our study addresses a major caveat of sugarcane production and affords a strong basis for improvement through breeding cultivars with enhanced capacity to use nitrate as well as through agronomic measures that reduce nitrification in soil.     

Gliricidia (Gliricidia sepium) Green manures as a potential source of N for maize production in the tropics

Use of cheap, N-rich, and environmentally benign legume green manures to correct N deficiency in infertile soils is a very attractive option in the humid tropics. Understanding the influence of management and climate on their effectiveness, and quantifying their contribution to crop productivity, is therefore crucial for technology adoption and adaptation. Mineral N buildup and the contribution to N uptake in maize were studied in an Ultisol amended with fresh Gliricidia leaves. Net mineral N accumulation was compared in mulched and incorporated treatments in a field incubation study. The 15 N isotope dilution technique was used to quantify N supplied to maize by Gliricidia leaves in an alley cropping. Mineral N accumulation was slow, but was much greater after incorporation than after mulching. Also, N buildup was always higher in the topsoil (0 to 10 cm) than in the subsoil (10 to 20 cm). More NO3-N was leached than NH4-N, and the effect was greater in the incorporated treatment. Surface-applied Gliricidia leaves significantly increased N uptake by maize, and supplied >30% of the total N in the stover and >20% of that in the corn grain, even in the presence of hedgerows. Thus Gliricidia leaf mulch has immense potential to improve productivity in tropical soils.     

N recovery from legume prunings and priming effects are governed by the residue quality

Nitrogen recovery from 15N-labelled prunings of Gliricidia sepium, Peltophorum dasyrrachis, Calliandra calothyrsus and Leucaena leucocephala, each of two different chemical qualities, was followed over three cropping cycles in a growth room. Half of the pots of each treatment received a further addition of unlabelled pruning material, from the same species as that previously applied, before the second and third crop cycle. The cumulative maize total N accumulation revealed the largest benefit from N rich, low lignin and polyphenols Gliricidia prunings followed by Leucaena, Calliandra and Peltophorum. Cumulative N recovery measured using 15N over the three crop cycles ranged from 9% from Calliandra prunings to 44% from Gliricidia prunings. The vast majority of this N was recovered during the first crop cycle which agreed well with estimates using the N difference method. Recoveries in the second and third crops ranged from 0.4–5% (15N method) and 6–14% (N difference method) of the N initially applied. The protein binding capacity of polyphenols was the best predictor of N recovery at both initial and later crop cycles. Treatments which led to a large N recovery initially, continued to provide greater N benefits in subsequent cycles although with increasing harvest time this trend decreased. Thus, there was no compensation in initial N release from low quality prunings at later harvests and the agronomic implications of this are discussed. Addition of unlabelled Gliricidia prunings before the second and third cycle led to a positive apparent priming effect on previously applied 15N labelled prunings. By contrast, repeated additions of Peltophorum residues, rich in lignin and active polyphenols, resulted in a reduced recovery of initially applied pruning-15N. However, the maximum positive or negative effects on recovery of pruning N amounted to less than 2% recovery of the initial amount of N added over 14 weeks. Thus the scope for regulation of N release from tree prunings during these later stages of decomposition appears to be limited.     

Equilibrium and balanced growth of a vegetative crop

MODEL: A previously developed dynamic model, NICOLET, designed to predict growth and nitrate content of a lettuce crop, is subjected to (virtual) constant environmental conditions. For every combination of shoot and root environment, the cell sap, here assumed to reside in the "vacuole" compartment, equilibrates at a certain nitrate concentration level. This, in turn, defines the composition of the crop in terms of carbon and nitrogen content in each of the three compartments of the model. Growth under constant environmental conditions is defined as "equilibrium" growth (EG). If, in addition, the source strengths of carbon and nitrogen balance each other, as well as the sink strength of the growing crop, the growth is said to be "balanced" (BG). RESULTS: It is shown that the range of BG approximately coincides with the range of "mild" nitrogen stress, where reduction in nitrogen availability results in a mild reduction of relative growth rate (RGR). Beyond a certain low nitrate concentration in the cell sap, the N-stress becomes "severe" and the loss of growth increases considerably. CONCLUSIONS: The model is able to mimic the five central observations of many constant-environment growth-chamber experiments, namely (1) the initial exponential growth and later decline of the RGR, (2) the constant chemical composition, (3) the equality of the RGR and the relative nutrient supply rate (RNR), (4) the proportionality between the N : C ratio and the RNR, and (5) the proportionality between the water content and the reduced N content. Guidelines for the optimal combination of the shoot and root environments are suggested.     

The carbon bonus of organic nitrogen enhances nitrogen use efficiency of plants

The importance of organic nitrogen (N) for plant nutrition and productivity is increasingly being recognized. Here we show that it is not only the availability in the soil that matters, but also the effects on plant growth. The chemical form of N taken up, whether inorganic (such as nitrate) or organic (such as amino acids), may significantly influence plant shoot and root growth, and nitrogen use efficiency (NUE). We analysed these effects by synthesizing results from multiple laboratory experiments on small seedlings (Arabidopsis, poplar, pine and spruce) based on a tractable plant growth model. A key point is that the carbon cost of assimilating organic N into proteins is lower than that of inorganic N, mainly because of its carbon content. This carbon bonus makes it more beneficial for plants to take up organic than inorganic N, even when its availability to the roots is much lower – up to 70% lower for Arabidopsis seedlings. At equal growth rate, root:shoot ratio was up to three times higher and nitrogen productivity up to 20% higher for organic than inorganic N, which both are factors that may contribute to higher NUE in crop production.     

The Arabidopsis halophytic relative Thellungiella halophila tolerates nitrogen-limiting conditions by maintaining growth, nitrogen uptake, and assimilation

A comprehensive knowledge of mechanisms regulating nitrogen (N) use efficiency is required to reduce excessive input of N fertilizers while maintaining acceptable crop yields under limited N supply. Studying plant species that are naturally adapted to low N conditions could facilitate the identification of novel regulatory genes conferring better N use efficiency. Here, we show that Thellungiella halophila, a halophytic relative of Arabidopsis (Arabidopsis thaliana), grows better than Arabidopsis under moderate (1 mm nitrate) and severe (0.4 mm nitrate) N-limiting conditions. Thellungiella exhibited a lower carbon to N ratio than Arabidopsis under N limitation, which was due to Thellungiella plants possessing higher N content, total amino acids, total soluble protein, and lower starch content compared with Arabidopsis. Furthermore, Thellungiella had higher amounts of several metabolites, such as soluble sugars and organic acids, under N-sufficient conditions (4 mm nitrate). Nitrate reductase activity and NR2 gene expression in Thellungiella displayed less of a reduction in response to N limitation than in Arabidopsis. Thellungiella shoot GS1 expression was more induced by low N than in Arabidopsis, while in roots, Thellungiella GS2 expression was maintained under N limitation but was decreased in Arabidopsis. Up-regulation of NRT2.1 and NRT3.1 expression was higher and repression of NRT1.1 was lower in Thellungiella roots under N-limiting conditions compared with Arabidopsis. Differential transporter gene expression was correlated with higher nitrate influx in Thellungiella at low (15)NO(3)(-) supply. Taken together, our results suggest that Thellungiella is tolerant to N-limited conditions and could act as a model system to unravel the mechanisms for low N tolerance.     

Drainage and nitrate leaching in a crop rotation under different N-fertilizer strategies: application of capacitance probes

Quantification of drainage and nitrate leaching from cropping systems is necessary to optimize N-fertilizer application and determine the impact on groundwater quality. The objectives of this work were to (i) assess the use of capacitance probes for the continuous determination of the volume of drainage water and the amount of nitrate leached in a crop production system, and (ii) compare the effect of different N-fertilizer strategies to control nitrate leaching in a crop rotation in humid Mediterranean climate. A factorial (control and three fertilizer strategies) experiment was conducted during three cropping seasons in Navarra (Spain). Wheat (Triticum aestivum L.) was planted in 2002, barley (Hordeum vulgare L.) in 2003, and rapeseed (Brassica napus L.) in 2004. Daily soil water content measurements based on capacitance probes were used to calculate drainage at 1 m depth, by applying the water balance equation. Nitrate leaching was calculated as the drainage volume multiplied by the nitrate concentration of the soil solution extracted in ceramic cups. The results revealed distinct behaviour in three crop phases, viz.: (i) from planting to GS-25, with high risk of drainage and nitrate leaching, (ii) from GS-25 to the end of the drainage period, with little drainage and leaching, and (iii) from then to harvest, when no drainage or nitrate leaching took place. Drainage and soil mineral N content before planting were the main factors determining the amount of N leached. Splitting N-fertilizer application and the use of nitrification inhibitors are not likely to have a significant impact on subsequent N-leaching losses, provided that the N-fertilizer application is adjusted to crop N needs corrected by soil N supply.     

Leaf litter decomposition of Piper aduncum,Gliricidia sepium and Imperata cylindrica in the humid lowlands of Papua New Guinea

No information is available on the decomposition and nutrient release pattern of Piper aduncum and Imperata cylindrica despite their importance in shifting cultivation systems of Papua New Guinea and other tropical regions. We conducted a litter bag study (24 weeks) on a Typic Eutropepts in the humid lowlands to assess the rate of decomposition of Piper aduncum, Imperata cylindrica and Gliricidia sepium leaves under sweet potato (Ipomoea batatas). Decomposition rates of piper leaf litter were fastest followed closely by gliricidia, and both lost 50% of the leaf biomass within 10 weeks. Imperata leaf litter decomposed much slower and half-life values exceeded the period of observation. The decomposition patterns were best explained by the lignin plus polyphenol over N ratio which was lowest for piper (4.3) and highest for imperata (24.7). Gliricidia leaf litter released 79 kg N ha^–1, whereas 18 kg N ha^–1 was immobilised in the imperata litter. The mineralization of P was similar for the three species, but piper litter released large amounts of K. The decomposition and nutrient release patterns had significant effects on the soil. The soil contained significantly more water in the previous imperata plots at 13 weeks due to the relative slow decomposition of the leaves. Soil N levels were significantly reduced in the previous imperata plots due to immobilisation of N. Levels of exchangeable K were significantly increased in the previous piper plots due to the large addition of K. It can be concluded that piper leaf litter is a significant and easily decomposable source of K which is an important nutrient for sweet potato. Gliricidia leaf litter contained much N, whereas imperata leaf litter releases relatively little nutrients and keeps the soil more moist. Gliricidia fallow is more attractive than an imperata fallow for it improves the soil fertility and produces fuelwood as additional saleable products.     

根系分区交替灌溉条件下水肥供应对番茄果实硝酸盐含量的影响

为了研究根系分区交替灌溉条件下灌水量和氮、磷、钾肥及有机肥用量对番茄果实硝酸盐含量的影响,采用五元二次正交旋转组合设计,通过盆栽试验,建立了番茄果实中硝酸盐含量与水肥因子的数学模型,并对各单一因素的效应及两两因素的耦合效应进行了分析。结果表明,在其他因子为中间水平时,番茄果实中的硝酸盐含量,随灌水量呈先降低后增加的变化规律;随施氮量和施磷量呈先增加后降低的变化趋势;随有机肥用量呈逐渐增加的趋势;但不受钾肥用量的影响。交互效应表现为,施磷量与有机肥用量、施氮量与施磷量间的相互作用会促使番茄果实硝酸盐含量提高;灌水量与施钾量和有机肥量、施氮量与施钾量间的相互作用有利于降低番茄果实硝酸盐累积。耦合效应表现为,除不施有机肥时随灌水量增加番茄果实硝酸盐含量显著增加外,对于其它任何有机肥及钾肥施用水平,果实硝酸盐含量皆随灌水量增加呈先减小后增加趋势;灌水量高于中水平时,番茄果实硝酸盐含量随着钾肥与有机肥用量的增加而减少。不论施磷量与施钾量如何变化,番茄果实硝酸盐含量皆随施氮量呈现先增加后减小的变化趋势,降低氮肥用量同时提高磷肥用量有利于降低番茄果实硝酸盐累积,而提高施钾量仅在施氮量高于中水平时能显著降低番茄果实硝酸盐含量。适当增加磷肥用量、减小有机肥用量能显著降低番茄果实硝酸盐的累积。     

Influence of nitrogen fertilization on tropical‐grass silage assessed by ensiling process monitoring using chemical and microbial community analyses

Aims: Utilization of silage in livestock farming is expected to increase in developing countries in the tropical and subtropical parts of the world. The aim of this study was to investigate the influence of nitrogen fertilization on the chemical composition of herbage, ensiling process and silage quality, and to contribute to the improvement of tropical‐grass silage preparation. Methods and Results: Guinea grass grown under two different nitrogen‐fertilizer application conditions [1·5 kg N a^?1 (high‐N) and 0·5 kg N a^?1 (low‐N)] was packed in plastic bags, and its ensiling process was investigated by chemical and microbial‐community analyses. Relatively well‐preserved silage was obtained from high‐N herbage, which accumulated a high nitrate concentration. Denaturing gradient gel electrophoresis analysis revealed that Lactobacillus plantarum dominated throughout the ensiling of high‐N herbage and in the early phase of that of low‐N herbage. In low‐N silages prepared from ammonium sulfate‐ and urea‐fertilized herbage, Lact. plantarum was replaced by clostridia after 40 and 15 days of ensiling, respectively. Conclusions: Nitrate content of herbage is an important factor that influences silage quality, and careful fertilization management can facilitate stable and successful fermentation of tropical‐grass silage without any pretreatment. Significance and Impact of the Study: The positive effect of nitrate on the ensiling process of tropical‐grass was proved by microbial‐community analysis.     

Effects of chemical composition on nitrogen mineralization from green manures of seven tropical leguminous trees

Green manures from seven tropical leguminous trees were incubated with soil to determine the rates and controls of net nitrogen release. Fresh green manure (leaves and succulent twigs) was mixed with moist soil and incubated in polyethylene bags. Net N mineralization from green manures was estimated by the accumulation of extractable ammonium and nitrate minus the accumulation in soil alone. Patterns of N mineralization were complex, differed among species, and at 12 weeks ranged from 10 to 65 percent of original green-manure N. Cumulative net N mineralization was negatively correlated with initial soluble polyphenol content in the early phases of decomposition (1 through 8 weeks) and with initial lignin content in later phases (4 through 12 weeks). Neither initial percent N nor lignin: N ratio were strongly correlated with N mineralization. The best chemical index of N release was the initial polyphenol: N ratio. This study confirms previous findings that N mineralization from tropical legumes is controlled more by soluble polyphenols than by lignin or N content.     

N‐ASSIMILATION IN THE NOXIOUS FLAGELLATE HETEROSIGMA CARTERAE (RAPHIDOPHYCEAE): DEPENDENCE ON LIGHT,N‐SOURCE,AND PHYSIOLOGICAL STATE1

The capabilities of the diel vertically migrating flagellate Heterosigma carterae Hulburt for assimilating ammonium and nitrate into cell‐N in light and in darkness were studied using cells of different N‐status. Ammonium utilization in darkness, except by N‐replete cells, attained>50% of use in the light. However, the capacity to use nitrate was poor in darkness, and less than 20% of nitrate‐N that was taken up in darkness was then actually incorporated into cell‐N. The ability to assimilate N in darkness improved as N‐status (N:C) declined, concurrent with an increasing content of water‐soluble carbohydrate. This carbohydrate was used to support dark N‐assimilation. Cells held in darkness for over a day and that had halted nitrate‐uptake were still capable of taking up ammonium. Furthermore, the act of taking up ammonium appeared to make available a source of C to support nitrate uptake that was previously unavailable. The implications of these results for the ecophysiology of this organism and for the construction of mathematical models of algal growth are considered.     

Soil nitrogen dynamics and relationships with maize yields in a gliricidia–maize intercrop in Malawi

Many soils of southern Africa are severely N deficient, but inorganic fertilizers are unaffordable for most subsistence farmers. Rotations and intercrops of legumes with crops may alleviate N deficiency through biological N₂ fixation and redistribution of subsoil N to the surface. We monitored soil inorganic N dynamics for two seasons in a gliricidia [Gliricidia sepium (Jacq.) Walp.] – maize (Zea mays L.) intercrop in the unimodal rainfall area of southern Malawi. One maize crop per year was grown with or without interplanted gliricidia, in factorial combination with three rates of N (0, 24 or 48 kg N ha^-1). Application of gliricidia prunings increased (p < 0.001) topsoil (0 to 20 cm) inorganic N at the end of the dry season and during the early rains. Differences between plus and minus gliricidia treatments were less when total inorganic N to 1-m depth was summed. A greater proportion of the total inorganic N to 1-m depth occurred in the topsoil (0 to 20 cm) when gliricidia was present, suggesting that redistribution of subsoil N to the surface accounted for part of the N increase by gliricidia. Gliricidia lowered (p < 0.05) subsoil water content during drier periods. Gliricidia plots accumulated more (p < 0.01) ammonium-N during the dry season. Nitrate-N remained constant during the dry season but rose rapidly in gliricidia plots after the onset of rains. A 2-factor model including preseason inorganic N and anaerobic N mineralization potential accounted for 84% of the variability in maize yields for the two seasons' data combined. The combination of preseason inorganic N and potential N mineralization appears to provide a good estimate of N supply to maize in systems receiving both organic and inorganic sources of N. This revised version was published online in June 2006 with corrections to the Cover Date.     

Alleviation of the adverse effects of salinity stress in wheat (Triticum aestivum L.) by seed biopriming with salinity tolerant isolates of Trichoderma harzianum

Use of an in-season measure of crop N sufficiency to guide fertilizer management is one approach to match the supply of N to the crop N demand. This study examined use of gene expression in leaf tissue of field-grown potatoes for use in assessment of potato N sufficiency. Potato cultivar ‘Shepody’ was grown with six fertilizer N rates (0–250 kg N ha^–1). Leaf disks were collected weekly for quantification of the expression of N uptake/transport, N assimilation, and amino acid metabolism genes in leaf tissue by nCounter. Many of the genes evaluated were responsive to crop N supply, but the response varied widely among sampling dates. The exception was an ammonium transporter gene (AT1) which was highly expressed, was relatively consistent across sampling dates, was closely related to root zone soil nitrate concentration across N rates and sampling dates, and was highly negatively correlated with total tuber yield. The level of expression of AT1 in leaf tissue was as good as or better than conventional chemical or optical measures of potato N sufficiency in the current study.     

模拟干旱和磷添加对热带低地雨林氮矿化过程的影响

土壤氮矿化作为氮转化的主要过程决定土壤供氮能力。热带森林生态系统往往受磷限制, 氮矿化过程对干旱的响应是否受磷限制的调控值得探讨。该研究以海南三亚甘什岭自然保护区热带低地雨林为研究对象, 利用2019年建立的林内穿透雨减少(50%)及磷添加双因素交互实验平台, 通过野外树脂芯原位培养法研究模拟干旱及磷添加对土壤无机氮(包括铵态氮和硝态氮)含量和氮矿化过程的影响。结果表明: 1)减雨处理显著降低了5和15 cm深度土壤的水分含量, 而对土壤温度没有显著影响。2)减雨处理和减雨与磷添加共同处理无论在旱季还是湿季对0-10 cm土壤无机氮含量均没有产生显著影响, 但磷添加处理在旱季显著降低了土壤硝态氮含量, 表明磷添加处理对氮有效性的影响主要体现在旱季, 而非湿季。3)干旱处理在旱季和湿季均显著降低了土壤净氨化速率和净氮矿化速率, 而磷添加处理和减雨与磷添加共同处理无论在旱季还是湿季对净氨化速率、净硝化速率和净氮矿化速率均没有产生显著影响, 结果表明了干旱能够显著降低土壤净氮矿化速率。4)土壤水分含量与土壤净氨化速率和净氮矿化速率呈显著正相关关系, 同时减雨处理显著影响了土壤净氨化速率与铵态氮含量的关系, 并且在铵态氮含量相等的情况, 随着干旱的影响净氨化速率下降得更快。这表明土壤水分含量变化是影响该研究样地土壤氮矿化的主要因素。上述研究结果说明, 降水变化对热带低地雨林中土壤氮矿化有重要影响, 短期磷添加没有显著影响, 减雨与磷添加对土壤氮矿化过程并没有交互效应。     

Use of a layered double hydroxide (LDH) to buffer nitrate in soil: long-term nitrate exchange properties under cropping and fallow conditions

The potential use of a layered double hydroxide (LDH) to act as a nitrate buffer system in soil in order to reduce the movement of nitrate was investigated. Long-term plant and soil experiments were carried out under greenhouse conditions with the following objectives: (i) evaluate the nitrate adsorption capacity of the LDH during crop growth, and its influence on N uptake, (ii) study the ability of the LDH to adsorb nitrate mineralized during fallow periods, and its influence on nitrate leaching, (iii) evaluate the reversibility for nitrate exchange of the LDH under cultivation conditions, and (iv) determine the nitrate buffer capacity of the soil after LDH application. The LDH adsorbed nitrate from the soil solution during the growth period without affecting plant N uptake. As a result of the adsorption of nitrate on the LDH, the nitrate-N concentration in the soil solution at harvest was reduced by a factor of ten compared to a soil without LDH. The LDH efficiently adsorbed nitrate that was mineralized in the soil during periods without cultivation, reduced nitrate-N leaching losses by about 80%, and kept this nitrate available for a following crop. The nitrate buffer capacity of the soil after 15months increased from 0.3 (without LDH) to 2.7 with the application of 10g LDH kg^?1 soil. It is concluded that the LDH has a potential to be used as a long-term nitrate exchanger to control the movement of nitrate in soil, and thereby reduce risks of nitrate leaching in crop production in sensible areas.     

Growth,pigment, and chromophoric dissolved organic matter responses of tropical Chattonella subsalsa (Raphidophyceae) to nitrogen enrichment

Blooms of the raphidophyte Chattonella subsalsa have been associated with massive fish‐kill events in several parts of the world. However, there have been few studies into physiological responses of tropical strains that could contribute to bloom outcomes. Such knowledge could provide insight into the C. subsalsa blooms recently documented within tropical coastal waters (e.g., 2010 and 2012 events in Singapore). Strains used in this study were isolated from the East Johor Straits (EJS), Singapore, an enclosed water channel frequently subjected to high levels of eutrophication. These cells were classified within the ‘global’ clade (and distinct from the ‘Adriatic Sea’ clade) based on morphology. The present study examined cellular responses to varying inputs of different forms of nitrogen (N), specifically nitrate, ammonium, and urea. Results from the study indicated that cells were unable to utilize urea as an N‐source, but grew well on a nitrate (V_max = 0.73 day^?1) and ammonium (V_max = 0.81 day^?1) supply. These growth rates were high compared to other strains from around the world, indicating that tropical C. subsalsa could exhibit elevated bloom potential within frequently eutrophic environments such as the EJS. Six pigments were detected in all cultures. These pigments were chlorophylls a and c; fucoxanthin; diadinoxanthin; violaxanthin; and β‐carotene. Chlorophyll‐a and fucoxanthin were the dominant pigments under both nitrate and ammonium regimes. Measurements of chromophoric dissolved organic matter generally increased both in molecular weight and in total content across the N‐concentration ranges. Such outcomes could have consequences for the chemical and optical conditions of the coastal environment.     

Vernonia galamensis,Potential new crop source of epoxy acid

Vernonia galamensis is a good source of seed oil rich in epoxy acid, which can be used to manufacture plastic formulations, protective coatings, and other products. Seed from a natural stand in Ethiopia contained 31% epoxy acid. Under cultivation in Kenya, this unimproved germplasm produced a substantial yield of seed with 32% epoxy acid. This African species has good natural seed retention and is a promising new crop for semiarid tropical areas.     

The profile of tropical alfalfa in Indonesia: A review

Alfalfa (Medicago sativa L.), or lucerne, is a subtropical plant popularly known as the “Queen of Forages”. It has a superior nutritional profile that includes high levels of crude protein, secondary metabolites, as well as macro and micro minerals, making it one of the best feed fodders in the world. Alfalfa is also highly adaptable to both warm and cold climates in addition to being highly nutritious. These features have led to the cultivation of alfalfa in tropical areas, such as Indonesia. Studies have been conducted on the vegetative and generative aspects of alfalfa cultivation in tropical regions to increase crop yield and sustainability. Progress in the cultivation and use of alfalfa in tropical regions has been encouraging and has led to the potential emergence of a new stock, namely tropical alfalfa, which is now a high-quality green forage source in tropical regions. Cultivation of tropical alfalfa provides breeders with a high-quality feed, leading to significant improvement in the condition and health of livestock and an increase in the production of meat, milk, and eggs. This review will be very important source of information not only for researchers but also for businessman who have a concern to develop alfalfa tropic either for feed or food (growth characteristic, function and nutrient content).