CPSC 116 Final Exam 2023 with complete solution questions and answers

What are some main morphological differences between monocots and dicots? monocots: 1 seed leaf, parallel leaf venation, flower parts groups of 3 dicots: 2 seed leaves, netted leaf venation, flower parts in groups of 4 or 5 Why is WUE better in C4 plants compared to C3 plants? C3 plants lose 97% of water to atmosphere, and in high light/temp conditions photorespiration occurs where O2 accumulates and CO2 is unavailable In C4 plants PEP transports CO2 to RuBisCo under bundle sheath cells, while diffusion of O2 is blocked by kratz anatomy What is the function of the phloem and the xylem? Phloem transports sugars, xylem transports water and minerals What is photorespiration? At high temps and light more O2 is produced by the plant which leads to RuBisCo binding to O2 instead of CO2. CO2 is then released. Photorespiration is always occuring and used for maintenance or growth What is the difference between soil texture and structure? Soil texture is the proportion of sand, silt, and clay Soil structure is the arrangement of soil particles and pore space between them What is Liebig's law of the minimum? surplus nutrients have no benefit until other limitations are relieved Which macronutrient has the greatest mobility in soil? Nitrogen is most susceptible to loss through NO3 and NH4+ What the 3Es of sustainability? Equity (society/people), Economy, Environment What are properties of agricultural systems with agroecology? Productivity, Stability, Sustainability, Equitability How does organic agriculture benefit from crop rotation? crop rotation can replenish soil nitrogen, reduce pest and pathogens, improve soil quality and soil fertility What is the 0.4% French Initiative? If we increase 0.4% a year the amount of carbon contained in the soils, we can halt the annual increase of CO2 in the atmosphere What are some basic organic standards? No inorganic fertilizers, no synthetic chemicals (herbicides, pesticides, fungicides), No GMOs What are the units of fertilizer analysis? N - P2O5 - K2O What are the benefits of using legumes in in organic agriculture? biological N fixation What are some typical small grains? Wheat, Barley, Rice, Oats Where is wheat primarily grown? EU > China > India > Russia > US What is the typical range of protein content in wheat? 9-15% protein What are some differences between spring and winter wheat? Winter wheat (70 bu avg, planted in fall harvest in summer, winterkill is a problem) Spring wheat (46 bu avg, plant spring harvest fall) What is the dilution effect? maintaining high yields without sacrificing protein is a major management challenge What are advantages of having tillers? Tillers compensate for empty space or takes advantage of good growing conditions How do insects impact winter wheat's planting date? Goal is to avoid planting before adult Hessian flies die, to prevent them from laying eggs in wheat fields. Less chance of aphids that carry Barley yellow dwarf virus. What is sustainable intensification? increase yield while decreasing environmental impact How do you calculate yield gap? Yield potential - Actual yield What are the most important variables influencing energy efficiency and net energy output? N fertilizer and fuel What are some options to increase water productivity in rainfed agricultural systems? Increase yields, Increase precipitation capture, Increase soil water storage, minimize losses all increase water productivity. Explain soil GHGs occurring in agriculture: CO2 (soil respiration, primarily offset by crop CO2 fixation), CH4 (flooded soils and livestock production), N2O (arable soils, N fertilizer and manure) Why is N2O such a concern? Fertilizer induced N2O emissions often represent over 50% of total CO2 equivalents for corn production What are the most influential factors when calculating carbon footprint? CO2 emissions related to inputs and fuel combustion, and changes in soil C What is evapotranspiration? Evapotranspiration is the combination of evaporation and transpiration What are the soil textures with the highest plant available water? silt loam, clay loam, clay hold the most water How do you calculate plant available water? Field capacity - Permanent Wilting Point Field capacity: The soil water content after free drainage (three days) of a saturated soil. Permanent Wilting Point: Water content at which soil has dried to the point that plants begin to wilt. Water is held to soil through cohesive and adhesive forces (matric potential) What is furrow irrigation? Crops in rows slightly elevated, sloped "furrows" between rows to convey water How do you increase WUE ratios? yield/ water applied, increase yield, prevent surface runoff, increase SOM, decrease evaporation What are the relative values of factors influencing soil water storage? Evaporation 30-50% Transpiration 15-30% Deep percolation: 10-30% Surface runoff: 10-25% What are the top 4 rice producing countries in the world? China, India, Indonesia, and Bangladesh account for 70% total global production What are the impacts of land leveling? Land leveling leads to better water management, improved germination/crop establishment, improved weed control, uniform crop maturity. What is puddling? When rice paddies are flooded to control weeds, manage residues, create hardpan to prevent water loss. What are some advantages of transplanting vs water-seeding? Transplanting: clean field- rice has a major head start Water seeding: Broadcast method What are some challenges of drill-seeding? drill seeded fields have problems with weed management and flash irrigation What are some harvest tradeoffs concerning waiting to for grain moisture to drop vs maintaining quality? Need to minimize risk of grain damage, dry down to less than 20% before harvest How does the U.S use its corn? Feed 40%, Fuel 31%, Export 8% What are the most expensive inputs for corn production? Fertilizer 43%, Seed 28% What percentage of corn planted is genetically modified? 90% of acres total of GE corn, 75% acres stacked (Bt and Ht) What are the effects of plant population on yield in poor vs excellent conditions? At excellent conditions and high plant population, yield plateaus At poor conditions and high plant population, yield decreases What does the black layer on corn seed mean? R6 stage, kernel has reached physiological maturity What is the Renewable Fuel Standard? Program that requires transportation fuel sold in the US to contain a minimum volume of renewable fuels. The goal is for 36 billion US gallons of renewable fuel to be used by 2022. What are 1st and 2nd generation biofuels? 1st gen: fuels that have been derived from sources like starch, sugar, animals fats, and vegetable oil. (Ethanol and biodiesel) 2nd gen: fuels that can be manufactured from different types of biomass. (switchgrass, Miscanthus) What are the limitations of 1st generation biofuels? First generation biofuels cannot produce enough biofuel without threatening fuel supplies also large carbon footprint. What are the advantages and disadvantages of biodiesel? Advantages: biodegradable and produces less air pollutants than petroleum-based diesel Disadvantages: expensive and not suitable for cold weather. What are some cellulosic biofuel sources Switchgrass, Miscanthus, energy cane. Which countries produce the most soybeans? US, Brazil, Argentina What is the meaning of indeterminate growth? vegetative growth occurs during reproductive growth What are the common soybean row width and seeding rates? 30in rows (100-150K plants), 15in row 175K plants What are the maintenance P and K rates for soybeans when compared to other crops? P2O5 0.85 lbs/bu, K2O 1.30 lbs/bu, very high compared to other crops What is the growth stage of soybean when flowering occurs? R1 beginning bloom (v6 to v10 stage), open flower at any node on the main stem, vertical root growth rates increase rapidly What are the yield components of soybeans? Number of plants and pods, seeds per pod, and seed weight