1Which region is widely considered a major centre of origin of cultivated Asian rice?
Rice: origin
Easy
A.South and Southeast Asia
B.Southern Australia
C.Northern Europe
D.Central Canada
Correct Answer: South and Southeast Asia
Explanation:
Cultivated Asian rice, Oryza sativa, is widely associated with South and Southeast Asia.
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2Which continent produces and consumes most of the world's rice?
Rice: geographical distribution
Easy
A.Europe
B.South America
C.Africa
D.Asia
Correct Answer: Asia
Explanation:
Asia is the leading continent in both rice production and rice consumption.
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3Which Indian state is a major rice-producing state?
Rice: geographical distribution
Easy
A.West Bengal
B.Gujarat
C.Rajasthan
D.Himachal Pradesh
Correct Answer: West Bengal
Explanation:
West Bengal is one of India's leading rice-producing states.
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4What is the main economic use of rice?
Rice: economic importance
Easy
A.Production of rubber
B.Use as a staple food
C.Production of fibre
D.Use as a beverage crop
Correct Answer: Use as a staple food
Explanation:
Rice is primarily grown as a staple food and supplies carbohydrates to a large population.
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5Which useful product is obtained from the outer brown layer removed during rice milling?
Rice: economic importance
Easy
A.Cotton lint
B.Rice bran
C.Cane molasses
D.Jute fibre
Correct Answer: Rice bran
Explanation:
Rice bran is removed during milling and is commonly used to extract edible rice bran oil.
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6Which soil is generally suitable for lowland rice cultivation because it retains water well?
Rice: soil and climatic requirements
Easy
A.Dry desert soil
B.Coarse gravelly soil
C.Clayey loam soil
D.Shallow sandy soil
Correct Answer: Clayey loam soil
Explanation:
Clayey loam soil has good water-holding capacity and is well suited to lowland rice.
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7Which climatic condition is most suitable for rice growth?
Rice: soil and climatic requirements
Easy
A.Frosty and windy climate
B.Warm and humid climate
C.Cool and arid climate
D.Cold and dry climate
Correct Answer: Warm and humid climate
Explanation:
Rice grows best under warm, humid conditions with an adequate supply of water.
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8Which of the following is a commonly cultivated high-yielding rice variety in India?
Rice: varieties
Easy
A.Pusa Basmati 1
B.JL 24
C.Varuna
D.HD 2967
Correct Answer: Pusa Basmati 1
Explanation:
Pusa Basmati 1 is a well-known improved aromatic rice variety cultivated in India.
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9What is the usual first step in transplanted rice cultivation?
Rice: cultural practices and yield
Easy
A.Milling harvested grains
B.Threshing dried plants
C.Harvesting mature panicles
D.Raising seedlings in a nursery
Correct Answer: Raising seedlings in a nursery
Explanation:
In transplanted rice, seedlings are first raised in a nursery and later moved to the main field.
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10What is the process of moving rice seedlings from a nursery to the main field called?
Rice: cultural practices and yield
Easy
A.Transplanting
B.Threshing
C.Winnowing
D.Milling
Correct Answer: Transplanting
Explanation:
Transplanting means moving young rice seedlings from the nursery and planting them in the prepared main field.
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11Which region is considered the primary centre of origin of maize?
Maize: origin
Easy
A.Southeast Asia
B.Central America
C.Central Africa
D.Western Europe
Correct Answer: Central America
Explanation:
Maize originated in Central America, particularly in the region of present-day Mexico.
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12Maize is widely cultivated in which type of regions?
Maize: geographical distribution
Easy
A.Tropical and temperate regions
B.Only desert regions
C.Only coastal regions
D.Only polar regions
Correct Answer: Tropical and temperate regions
Explanation:
Maize is adaptable and is grown extensively in both tropical and temperate regions.
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13Which Indian state is a major producer of maize?
Maize: geographical distribution
Easy
A.Sikkim
B.Tripura
C.Karnataka
D.Goa
Correct Answer: Karnataka
Explanation:
Karnataka is one of the major maize-producing states in India.
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14Which is a major use of maize grain?
Maize: economic importance
Easy
A.Commercial fibre production
B.Natural rubber production
C.Tea beverage production
D.Food and animal feed
Correct Answer: Food and animal feed
Explanation:
Maize grain is widely used as human food and as an important ingredient in animal feed.
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15Which industrial product is commonly manufactured from maize?
Maize: economic importance
Easy
A.Maize starch
B.Natural latex
C.Raw silk
D.Jute fibre
Correct Answer: Maize starch
Explanation:
Maize is an important raw material for manufacturing starch and several starch-based products.
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16Which soil condition is most suitable for maize cultivation?
Maize: soil and climatic requirements
Easy
A.Permanently frozen soil
B.Deep waterlogged clay
C.Well-drained fertile loam
D.Highly saline marsh soil
Correct Answer: Well-drained fertile loam
Explanation:
Maize performs well in fertile loam soils that provide good drainage and aeration.
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17Which weather condition can seriously damage a maize crop?
Maize: soil and climatic requirements
Easy
A.Moderate sunshine
B.Warm weather
C.Severe frost
D.Light wind
Correct Answer: Severe frost
Explanation:
Maize is sensitive to severe frost and generally requires warm, frost-free growing conditions.
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18Which of the following is an improved maize variety or hybrid?
Maize: varieties
Easy
A.Sonalika
B.Pusa Bold
C.Jaya
D.Ganga 5
Correct Answer: Ganga 5
Explanation:
Ganga 5 is a well-known maize hybrid developed for cultivation in India.
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19Which sowing method is commonly used to maintain proper spacing in maize?
Maize: cultural practices and yield
Easy
A.Line sowing
B.Dense broadcasting
C.Deep puddling
D.Random flooding
Correct Answer: Line sowing
Explanation:
Line sowing provides uniform spacing and makes weeding, fertilizer application, and other field operations easier.
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20At which stage is maize generally harvested for grain?
Maize: cultural practices and yield
Easy
A.Before seed germination
B.During early seedling growth
C.At physiological maturity
D.Immediately after tasseling
Correct Answer: At physiological maturity
Explanation:
Grain maize is harvested at physiological maturity, when the kernels are fully developed and begin to lose moisture.
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21Archaeological evidence and the diversity of cultivated rice suggest that the primary centre of origin of Asian rice is associated with which region?
Rice: origin
Medium
A.Southern Africa and Madagascar
B.Central and western Europe
C.South and Southeast Asia
D.North America and Mexico
Correct Answer: South and Southeast Asia
Explanation:
Asian rice, Oryza sativa, is generally considered to have originated through domestication in South and Southeast Asia, where substantial diversity of the crop occurs.
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22A farmer in a warm, humid lowland region with seasonal flooding is selecting a cereal crop. Which characteristic makes rice especially suitable for this location?
Rice: geographical distribution
Medium
A.Dependence on very dry sandy conditions
B.Best growth under frost-prone highlands
C.Requirement for prolonged winter chilling
D.Tolerance of standing water during cultivation
Correct Answer: Tolerance of standing water during cultivation
Explanation:
Lowland rice is adapted to warm, humid environments and can grow under flooded or saturated soil conditions that would severely restrict many other cereals.
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23Which combination correctly matches major rice products with their source parts?
Rice: economic importance
Medium
A.Edible starch from roots and rubber from straw
B.Cane sugar from husk and latex from bran
C.Wool from husk and fiber from polished grains
D.Bran oil from bran and straw from stalk residues
Correct Answer: Bran oil from bran and straw from stalk residues
Explanation:
Rice bran can be processed for edible oil, while rice straw is used as animal feed, bedding, thatching material, and for other purposes.
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24Which field is generally most suitable for transplanted lowland rice?
Rice: soil and climatic requirements
Medium
A.Frozen upland soil with a short growing season
B.Level clay loam with good water-holding capacity
C.Steep gravelly slope with rapid drainage
D.Deep dry sand with very low nutrient retention
Correct Answer: Level clay loam with good water-holding capacity
Explanation:
Level clay loam soils retain water, support puddling, and reduce seepage, making them suitable for transplanted lowland rice.
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25Rice requires abundant water during much of its growth, but which condition is especially important during flowering and grain filling?
Rice: soil and climatic requirements
Medium
A.Warm weather without severe water stress
B.Very low temperature and prolonged drought
C.Frequent frost with dry atmospheric conditions
D.Continuous deep flooding over the panicles
Correct Answer: Warm weather without severe water stress
Explanation:
Warm conditions and adequate moisture during flowering and grain filling support pollination, grain development, and yield. Severe stress at these stages can cause sterility and poor grain filling.
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26A farmer wants a rice variety that can escape late-season drought by completing its life cycle quickly. Which varietal trait is most useful?
Rice: varieties
Medium
A.Early maturity
B.Very tall plant height
C.Long photoperiod sensitivity
D.Extremely late grain filling
Correct Answer: Early maturity
Explanation:
Early-maturing varieties complete growth sooner and can reduce exposure to terminal drought or delayed water availability.
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27Why is puddling commonly carried out before transplanting rice seedlings?
Rice: cultural practices and yield
Medium
A.To prevent the soil from holding nutrients
B.To promote rapid drainage from the field
C.To reduce water loss through soil pores
D.To increase soil aeration for deep roots
Correct Answer: To reduce water loss through soil pores
Explanation:
Puddling destroys large soil pores and forms a less permeable layer, reducing percolation losses and making it easier to maintain standing water.
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28Rice seedlings are often transplanted at a relatively young age because young seedlings generally establish more rapidly and produce:
Rice: cultural practices and yield
Medium
A.Fewer roots and weaker shoots
B.More productive tillers
C.Lower nutrient uptake throughout growth
D.Longer transplanting shock periods
Correct Answer: More productive tillers
Explanation:
Properly aged young seedlings recover quickly after transplanting and usually develop better root systems and more productive tillers than over-aged seedlings.
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29A rice field remains continuously flooded with unnecessarily deep water. Which management change is most likely to improve water-use efficiency without exposing the crop to prolonged drought?
Rice: cultural practices and yield
Medium
A.Increase the water depth throughout the season
B.Drain the field permanently after transplanting
C.Irrigate only once before sowing the nursery
D.Use shallow irrigation with periodic drainage
Correct Answer: Use shallow irrigation with periodic drainage
Explanation:
Maintaining shallow water and allowing controlled drying intervals can reduce water losses while preserving adequate moisture for rice growth.
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30Which situation is most likely to reduce rice yield even when the crop receives adequate nitrogen?
Rice: cultural practices and yield
Medium
A.Severe weed competition during early growth
B.Adequate moisture during flowering
C.Uniform plant spacing with healthy seedlings
D.Timely weed control during early growth
Correct Answer: Severe weed competition during early growth
Explanation:
Early-season weeds compete strongly with rice for light, nutrients, water, and space. This competition can permanently reduce tillering and final yield.
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31Maize is believed to have been domesticated primarily in which region?
Maize: origin
Medium
A.The Mediterranean basin
B.Northern China and Korea
C.The Nile valley of Africa
D.Mesoamerica, especially Mexico
Correct Answer: Mesoamerica, especially Mexico
Explanation:
Maize was domesticated in Mesoamerica, with Mexico recognized as a major centre of its origin and early diversification.
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32Maize can be grown over a wide geographical range mainly because it has:
Maize: geographical distribution
Medium
A.A dependence on permanent standing water
B.A strict requirement for one narrow latitude
C.Many maturity groups adapted to different climates
D.An inability to grow outside tropical lowlands
Correct Answer: Many maturity groups adapted to different climates
Explanation:
Differences in maturity duration and adaptation among maize varieties allow production from tropical regions to temperate areas.
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33Which feature explains why maize is important both as a food crop and as an industrial raw material?
Maize: economic importance
Medium
A.Its grain supplies starch, oil, feed, and processed products
B.Its pollen is harvested as the principal food grain
C.Its leaves produce most commercial vegetable oils
D.Its roots are the main source of edible sugar
Correct Answer: Its grain supplies starch, oil, feed, and processed products
Explanation:
Maize grain is used directly as food and livestock feed and is processed into starch, oil, glucose, ethanol, and several other products.
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34Which soil would generally provide the best conditions for a high-yielding maize crop under rainfed management?
Maize: soil and climatic requirements
Medium
A.Fertile, well-drained loam with adequate moisture
B.Very shallow gravel soil with low water storage
C.Waterlogged heavy clay with poor drainage
D.Highly saline soil without any amendment
Correct Answer: Fertile, well-drained loam with adequate moisture
Explanation:
Maize performs well in fertile, well-drained loam soils that provide moisture while allowing sufficient root-zone aeration.
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35A maize crop experiences drought around silking and pollen shed. What is the most likely effect on yield?
Maize: soil and climatic requirements
Medium
A.No effect because maize is insensitive during reproduction
B.Greater kernel number because water stress shortens flowering
C.Poor pollination and increased kernel loss
D.Improved synchronization of silking and pollen shed
Correct Answer: Poor pollination and increased kernel loss
Explanation:
Water stress during flowering can delay silk emergence, reduce pollen viability, and create a mismatch between pollen shed and silking, resulting in fewer kernels.
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36A farmer wants to maximize yield under uniform management and has access to quality seed each season. Which maize type is generally the most appropriate choice?
Maize: varieties
Medium
A.A volunteer crop from the previous season
B.A highly variable wild relative
C.An unselected local mixture
D.A recommended single-cross hybrid
Correct Answer: A recommended single-cross hybrid
Explanation:
Single-cross hybrids often provide high and uniform yield because of heterosis, but fresh quality seed is normally required for each crop season.
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37Which varietal characteristic is most valuable for reducing lodging losses in a high-input maize crop?
Maize: varieties
Medium
A.Very weak stalks with excessive height
B.Strong stalks with moderate plant height
C.Soft stalks with dense surface leaves
D.Thin stems with delayed maturity
Correct Answer: Strong stalks with moderate plant height
Explanation:
Strong stalks and moderate plant height improve standability and reduce lodging, especially when high fertility increases vegetative growth.
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38Why should maize be planted at an optimum and uniform spacing rather than at a very high plant density?
Maize: cultural practices and yield
Medium
A.To balance population with light, water, and nutrients
B.To eliminate the need for seed treatment
C.To prevent the crop from using soil nitrogen
D.To ensure every plant develops multiple ears
Correct Answer: To balance population with light, water, and nutrients
Explanation:
Optimum spacing provides enough resources per plant while achieving an adequate population. Excessive density increases competition and may reduce ear size and grain yield.
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39A maize farmer wants to apply nitrogen efficiently. Which practice is generally most suitable for reducing losses and matching crop demand?
Maize: cultural practices and yield
Medium
A.Split nitrogen applications, including one near rapid growth
B.Apply all nitrogen several months before sowing
C.Avoid nitrogen because maize fixes atmospheric nitrogen
D.Apply all nitrogen after physiological maturity
Correct Answer: Split nitrogen applications, including one near rapid growth
Explanation:
Splitting nitrogen applications improves synchronization with crop demand and can reduce leaching, volatilization, and other nutrient losses.
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40Which field condition is most likely to cause a major maize yield reduction during the first month after emergence?
Maize: cultural practices and yield
Medium
A.Severe weed competition during the critical early period
B.Timely interculture between maize rows
C.Uniform emergence with adequate soil moisture
D.Good drainage after moderate rainfall
Correct Answer: Severe weed competition during the critical early period
Explanation:
Maize is sensitive to early weed competition. Weeds can reduce plant growth and leaf area during the period when the crop is establishing its yield potential.
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41Which inference best supports the accepted origin of cultivated Asian rice (Oryza sativa) in the Yangtze basin of China?
Rice: origin
Hard
A.Its wild relatives occur exclusively in the African savannas
B.Its earliest domestication evidence is associated with humid river-valley settlements
C.Its primary domestication center was the Andean highlands
D.Its cultivation began in dry Mediterranean winter-rainfall zones
Correct Answer: Its earliest domestication evidence is associated with humid river-valley settlements
Explanation:
Archaeobotanical evidence and the distribution of related wild rice support an East Asian, particularly Yangtze-basin, origin for Oryza sativa.
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42A farmer in a humid tropical delta wants a rice type that flowers when day length decreases and is adapted to warm conditions. Which ecogeographical group is most likely suitable?
Rice: geographical distribution
Hard
A.Indica rice adapted mainly to tropical and subtropical regions
B.Aromatic rice restricted to Mediterranean environments
C.Japonica rice restricted to cool temperate uplands
D.Temperate japonica rice requiring long summer days
Correct Answer: Indica rice adapted mainly to tropical and subtropical regions
Explanation:
Indica types are widely grown in tropical and subtropical Asia and generally perform well under warm conditions and shorter-day seasonal environments.
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43Why can a rice-processing policy that increases the recovery of broken rice still improve food-system efficiency?
Rice: economic importance
Hard
A.Broken rice retains substantial starch and can enter food or industrial markets
B.Broken rice eliminates the need for drying after harvest
C.Broken rice contains more protein than intact rice grains
D.Broken rice has a higher milling value than whole kernels
Correct Answer: Broken rice retains substantial starch and can enter food or industrial markets
Explanation:
Although broken kernels receive a lower market price, they remain useful for flour, feed, brewing, starch, and other products, reducing processing losses.
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44Which soil condition most directly explains why puddling can benefit transplanted lowland rice but impair the following upland crop?
Rice: soil and climatic requirements
Hard
A.It converts all soil nitrogen into immediately available nitrate
B.It raises soil salinity while permanently increasing phosphorus availability
C.It reduces percolation but creates a dense layer that restricts root penetration
D.It increases deep drainage and improves aeration throughout the profile
Correct Answer: It reduces percolation but creates a dense layer that restricts root penetration
Explanation:
Puddling reduces water loss from the flooded layer, but the compacted puddled zone may restrict roots, drainage, and aeration for a succeeding non-puddled crop.
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45Rice plants show severe sterility during flowering despite adequate water and nutrients. Which weather event is the most probable cause?
Rice: soil and climatic requirements
Hard
A.High humidity during the grain-filling phase
B.Moderate rainfall during the tillering phase
C.A brief low-temperature episode during anthesis
D.A warm night during early vegetative growth
Correct Answer: A brief low-temperature episode during anthesis
Explanation:
Rice is particularly sensitive to chilling around meiosis and flowering; low temperature can disrupt pollen development and fertilization, causing spikelet sterility.
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46A variety is selected for flood-prone fields where plants may remain submerged for about two weeks. Which trait should receive the greatest priority?
Rice: varieties
Hard
A.High susceptibility to elongation under deep water
B.Strong photoperiod insensitivity with shallow rooting
C.Submergence tolerance associated with the SUB1 response
D.Photoperiod sensitivity causing very late flowering
Correct Answer: Submergence tolerance associated with the SUB1 response
Explanation:
SUB1-type tolerance limits excessive elongation and conserves carbohydrates during complete submergence, improving survival after flood recession.
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47Which varietal combination is most appropriate when a rice-growing region has saline irrigation water, frequent lodging, and a short transplanting window?
Rice: varieties
Hard
A.Salt sensitivity, vigorous elongation, and extended maturity
B.Tall stature, weak culms, and strong late-season photoperiod response
C.High plant height, shallow roots, and very late maturity
D.Salt tolerance, semi-dwarf stature, and suitable maturity duration
Correct Answer: Salt tolerance, semi-dwarf stature, and suitable maturity duration
Explanation:
The combination addresses the three constraints: salinity tolerance protects establishment, semi-dwarf plants reduce lodging, and suitable duration fits the available season.
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48In a transplanted rice field, seedlings are excessively old, planted deeply, and kept continuously flooded immediately after transplanting. Which yield loss mechanism is most likely?
Rice: cultural practices and yield
Hard
A.Enhanced nitrogen fixation and improved seedling vigor
B.Delayed establishment and reduced productive tiller formation
C.Reduced transplanting shock through deeper crown burial
D.Accelerated root growth and increased panicle initiation
Correct Answer: Delayed establishment and reduced productive tiller formation
Explanation:
Old seedlings and deep planting slow recovery, while early flooding restricts oxygen and encourages weak establishment, reducing productive tillers and final yield.
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49A rice crop has many panicles but a low grain yield. Grain sampling shows poor grain filling rather than excessive empty hills. Which yield component should be investigated first?
Rice: cultural practices and yield
Hard
A.Filled grains per panicle and grain-filling conditions
B.Plant population alone during early seedling growth
C.Number of hills harvested after threshing
D.Seed purity before nursery sowing only
Correct Answer: Filled grains per panicle and grain-filling conditions
Explanation:
Yield depends on panicles, grains per panicle, filled-grain percentage, and grain weight; abundant panicles cannot compensate for poor filling.
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50Which irrigation strategy is most defensible for a well-leveled lowland rice field when the goal is to reduce water use without exposing plants to severe drought?
Rice: cultural practices and yield
Hard
A.Allow shallow water depletion before re-irrigating while avoiding severe cracking
B.Maintain a deep standing-water layer from transplanting to harvest
C.Drain the field continuously from transplanting through panicle emergence
D.Irrigate only after permanent wilting symptoms appear in the crop
Correct Answer: Allow shallow water depletion before re-irrigating while avoiding severe cracking
Explanation:
Alternate wetting and drying can reduce unproductive water losses while maintaining adequate moisture, provided severe soil drying is avoided during sensitive stages.
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51A farmer incorporates large amounts of fresh, high-carbon straw immediately before rice transplanting. Which management adjustment is most appropriate?
Rice: cultural practices and yield
Hard
A.Account for temporary nitrogen immobilization and adjust nitrogen timing
B.Apply all nitrogen before incorporation to prevent microbial competition
C.Flood deeply and continuously to convert all straw carbon into nitrate
D.Eliminate all nitrogen because straw decomposition releases sufficient nitrogen
Correct Answer: Account for temporary nitrogen immobilization and adjust nitrogen timing
Explanation:
Microorganisms decomposing high-carbon residues may temporarily immobilize mineral nitrogen, so nitrogen placement and split timing should be adjusted.
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52Which distribution pattern best explains why rice is dominant in monsoonal Asian plains but also cultivated in irrigated regions outside Asia?
Rice: geographical distribution
Hard
A.It combines adaptation to warm seasons with the ability to exploit controlled flooding
B.It requires only cool climates and cannot tolerate standing water
C.It evolved exclusively under dryland conditions and avoids humid regions
D.It is restricted to naturally fertile soils with no irrigation requirement
Correct Answer: It combines adaptation to warm seasons with the ability to exploit controlled flooding
Explanation:
Rice thrives in warm environments and can use abundant or managed water, allowing extensive production in monsoonal plains and irrigated areas worldwide.
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53Which evidence most strongly links modern maize to teosinte rather than to an independent domestication from an unrelated grass?
Maize: origin
Hard
A.Teosinte is distributed only in regions where maize was never cultivated
B.Maize possesses a completely independent chromosome organization
C.Genetic and morphological continuity occurs between maize and teosinte populations
D.Modern maize has no homologous structures with any wild grass
Correct Answer: Genetic and morphological continuity occurs between maize and teosinte populations
Explanation:
Comparative genetics and morphology identify teosinte, especially Zea mays ssp. parviglumis, as the principal progenitor of cultivated maize.
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54Why can maize be grown across a wider range of latitudes than many tropical cereals?
Maize: geographical distribution
Hard
A.It has diverse maturity groups and strong photothermal adaptation
B.It requires identical day length and temperature in every region
C.It completes grain filling independently of temperature and radiation
D.It is insensitive to frost, drought, and heat during reproductive growth
Correct Answer: It has diverse maturity groups and strong photothermal adaptation
Explanation:
Variation in maturity, photoperiod response, and temperature adaptation allows maize cultivars to fit tropical, subtropical, and temperate production zones.
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55A region diverts a large share of maize from food to feed and bioethanol. Which consequence is most technically accurate?
Maize: economic importance
Hard
A.Demand becomes linked to livestock and energy markets as well as food markets
B.Feed and fuel demand removes all effects of storage and price variation
C.Industrial use guarantees higher grain yield in the field
D.Maize ceases to contribute protein or energy to human diets
Correct Answer: Demand becomes linked to livestock and energy markets as well as food markets
Explanation:
Maize is a food, feed, and industrial crop, so changes in livestock production, fuel policy, and processing capacity can influence its demand and price.
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56A maize field has adequate rainfall but remains waterlogged after storms. Which yield penalty is most likely if waterlogging occurs near tasseling and silking?
Maize: soil and climatic requirements
Hard
A.Greater oxygen supply to roots and enhanced pollen shedding
B.Earlier physiological maturity with no effect on grain filling
C.Poor root function and impaired pollination leading to barren or poorly filled ears
D.Improved nutrient uptake and increased kernel number per ear
Correct Answer: Poor root function and impaired pollination leading to barren or poorly filled ears
Explanation:
Waterlogging reduces root respiration and nutrient uptake; around flowering it can disrupt silk emergence, pollen function, and kernel set.
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57Why is a deep, well-drained loam generally preferred for high-yielding maize compared with a shallow compact clay soil?
Maize: soil and climatic requirements
Hard
A.It prevents all drought stress by storing unlimited plant-available water
B.It removes the need for nitrogen because roots mineralize soil organic matter completely
C.It supports extensive roots while balancing water retention, aeration, and nutrient supply
D.It produces maximum yield regardless of temperature during flowering
Correct Answer: It supports extensive roots while balancing water retention, aeration, and nutrient supply
Explanation:
Maize has a large, active root system and responds strongly to soil structure; deep, well-drained loam provides both moisture storage and oxygen.
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58A farmer wants to save seed from a high-performing maize hybrid for the next season. Why is this practice generally unsuitable?
Maize: varieties
Hard
A.Hybrid seed cannot germinate after it is harvested from mature ears
B.All saved hybrid seed becomes genetically identical to the female parent
C.The second generation always matures earlier than the original hybrid
D.Segregation in the progeny can reduce uniformity and hybrid advantage
Correct Answer: Segregation in the progeny can reduce uniformity and hybrid advantage
Explanation:
F1 hybrids are genetically uniform, but their saved seed segregates in the F2 generation, often causing variable plant type, maturity, disease response, and yield.
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59Which maize cultivar choice best matches a short, frost-limited growing season with a narrow harvest window?
Maize: varieties
Hard
A.A long-duration cultivar requiring an extended frost-free period
B.A late-maturing cultivar selected only for maximum tropical biomass
C.An early-maturing cultivar with reliable cold-season establishment
D.A strongly photoperiod-sensitive cultivar with delayed flowering
Correct Answer: An early-maturing cultivar with reliable cold-season establishment
Explanation:
Early maturity reduces the risk of frost before physiological maturity, while cold-tolerant establishment improves emergence and early growth.
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60A maize crop has adequate plant population and healthy leaves, but silks emerge several days after pollen shed during hot, dry weather. What is the most likely yield consequence?
Maize: cultural practices and yield
Hard
A.Greater ear length because silk growth is prolonged without stress
B.Higher test weight because drought accelerates fertilization
C.Asynchronous flowering causing poor kernel set, especially near the ear tip
D.Increased kernel number because delayed silks receive more pollen
Correct Answer: Asynchronous flowering causing poor kernel set, especially near the ear tip
Explanation:
Heat and moisture stress can delay silk emergence relative to pollen shed, reducing fertilization and producing partially barren ears.
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