the main object of crop cultivation research is ().
there are some differences in crop species and technical level in different regions, because of the ( ) results of crop cultivation.
different crops are planted in different seasons because of the ( ) results of crop cultivation.
the following are not crops ( ).
crops can be ided into c3 crops and c4 crops according to the ()way of assimilation.
with good varieties, it will be able to produce high yield.
the goal of crop production is only to achieve high yield.
the origin and formation of crops are the product of natural selection and human labor.
rape is a common oil crop.
generally, the yield of crops is ided into biological yield and economic yield.
wheat belongs to ( ).
the dry weight of wheat kernel in ( ) reached the maximum.
the yield per unit area of wheat is composed of spikes per unit area, ( ) and kernel weight.
the basis for determining the appropriate sowing date of winter wheat is ( ) and the characteristics of variety development.
currently cultivated common wheat is diploid.
the whole life of wheat refers to the process from seed germination to the generation of new seeds.
the higher the temperature, the faster the grain filling rate of wheat.
the processing quality of wheat grain can be ided into primary processing quality and secondary processing quality.
the earlier spring wheat is sown, the better.
how many seed roots are there in rice?
what is the beginning of the reproductive growth period of rice?
which continent in the world has the largest area of rice cultivation?
at what time did the root system of rice grow?
what is the critical period for determining the panicle number of rice?
the cold resistance of japonica rice is stronger than that of indica rice.
cultivated rice is a member of the genus plant taxonomy in the cruciferous family.
the root of rice can be ided into white root, yellow root and black root in appearance, and yellow root has the strongest activity.
china is the largest rice-growing country in the world.
( ) is the world's largest corn producer.
the important sign of physiological maturity of corn is ( ).
with the increase in planting density, corn production can continue to increase.
the following non potato related names are ( ).
potato originated from ( ).
potato chips grow at the top of ( ).
the main product organ of potato is ( ).
the storage temperature of edible potato is about ( ).
potatoes originated in china.
the growth period of tuber is the critical period of potato water requirement.
the starch content of potato tuber is about 12% - 22%.
which country has the largest cotton planting area in the world in 2018?
the most important factor causing the shedding of cotton is ( ).
what is the most widely used growth regulator in cotton production?
the main component of cotton fiber is cellulose.
cotton cannot be harvested by machinery.
the yield components of rape are composed of four factors: number of plants per unit area, number of pods per plant, number of seeds per pod and ( ).
the fruits of rape are developed from ( ).
what is on the stem segment or branch of the upper part of the main stem?
spring rape refers to the rape that be sown in（）and harvested in autumn.
press oil from rape flowers and leaves in production.
the root of rape is straight root.
rape is not sensitive to light and temperature.
rape mainly depends on pod photosynthesis to form yield, but leaf photosynthesis has no contribution to yield.
soybean is a typical ( ) crop.
the raw material of tofu is ( ).
soybean top dressing time is generally ( ) .
soybeans are ( ) crops.
soybeans should not be used to extract oil.
soybean seeds can also germinate below 0 ℃.
millet originated from ( ).
the lowest temperature of millet germination is ( ).
millet is ( ).
the root of millet is ( ).
millet originated in the united states.
the roots of sorghum are straight roots.
sorghum is a light loving crop. in the process of growth and development, sufficient light conditions are required.
sorghum has strong ability of drought resistance. it can not only resist soil drought, but also atmospheric drought.
wheat belongs to ( ).
common wheat currently cultivated is ( ).
wheat originated from ( ).
in the comprehensive external conditions required for the vernalization stage, the leading role is ( ).
generally, there are () wheat seed roots.
tillers growing from the main stem of wheat are ( ).
the optimum temperature for wheat grain formation and filling is ( ).
the dry weight of wheat grain reached the maximum value in ( ).
the quality of wheat grain includes ( ) and processing quality.
( ) endosperm wheat is suitable for making biscuits.
( ) wheat can be used to produce higher grade bread.
the basis for determining the suitable sowing date for winter wheat is ( ) and cultivars development characteristics.
the irrigation technology mainly involves irrigation quantity and period and ( ).
() is the leading factor of crop yield and quality, and is the internal factor.
the research content of crop cultivation should be adjusted with the change of ().
it can be said that the foundation of human culture starts from (), which has been confirmed by the development history of human society and archaeology.
the purpose of understanding the origin of cultivated plants is ().
central china and () are the world's largest agricultural birthplace and the origin center of cultivated plants.
the harvest of the products people need for cultivation purposes is called ().
from the formation process of crop yield, all kinds of crops can be ided into three stages: early growth stage () and late growth stage.
the panicle of rice is () inflorescence.
there are () seed roots in rice.
the key period to determine the panicle number of rice is () period.
generally, () is used as a marker of the beginning of rice reproductive growth period.
the world's largest rice growing continent is ().
the cold resistance of japonica rice is higher than that of indica rice.
the most important mineral element affecting rice tillering is ().
generally speaking, the product organ of potato is ().
the fruit of potato is ().
potatoes belong to the () family.
what family does cotton belong to in botanical classification？
what is the most cultivated cotton in the world?
what is the main part of cotton fiber?
rapeseed roots can secrete organic acids and dissolve insoluble ( ) in the soil.
each flower of rape has 4 calyxes, 4 petals and ( ) stamens.
how many pistils does each rape flower have?
rape is a ( ) crop.
soybean originated in ( ).
the soybean flower has ( ) stamens.
soybeans are ( ) crops.
soybean pods are developed from the ( ).
the seed navel of soybean is the scar left on the seed coat after the seed is free from the ( ).
millet originated in ( ).
the period when the millet needs the most water is from ( ).
millet is a ( ) crop.
sorghum for brewing requires grain starch content not less than ( ).
corn belongs to ( ).
( ) is recognized as the king of feed.
the spikelets of millet are born on ( ) branches.
there are 2 glumes in each spikelet of millet, and there are ( ) all flowers in it.
sorghum is a ( ) crop.
insufficient moisture from the sorghum ( ) will cause "jam drought".
the maximum period of sorghum water requirement is from ( ).
the critical period of sorghum water requirement is ( ).
sorghum spikes are ( ).
() is the world's largest corn producer.
with the increasing density of corn planting, ( ).
the following c4 crops are ( ).
the corn root system is composed of radicle and ( ).
( ) corn is more suitable for high-density planting.
the period when corn needs the most fertilizer is ( ).
which of the following is not the main function of the root ( ).
corn should be planted during ( ).
the total output ranks first among cereal crops ( ).
the main root system of corn is distributed in ( ) soil layer.
the longest, widest and largest leaf area of corn is generally ( ).
the main root system of corn is ( ).
the processing quality of wheat grain is ided into ( ).
the wheat population structure include ( ).
the distribution of wheat population refers to the distribution of wheat plants in ( ) directions.
currently cultivated common wheat is diploid.
according to the sowing season, wheat can be ided into spring wheat and winter wheat.
wheat is one of the most important food crops in china, which is mainly used in industry.
the whole life of wheat refers to the process from seed germination to new seed generation.
wheat seed belongs to caryopsis in botany.
the cortex of wheat seed protects embryo and endosperm.
there is no relationship between the appearance of tillers and the appearance of main stem leaves.
the high tiller of wheat is easy to form ear.
the higher the temperature, the faster the grain filling rate.
the later the wheat harvest, the better.
the earlier the spring wheat is sown, the better.
the later the wheat harvest, the better.
the processing quality of wheat grain can be ided into primary processing quality and secondary processing quality.
the research of biological high technology will not promote the development of crop cultivation.
rice is grown on every continent in the world, but mainly in asia.
the difference of growth period of rice varieties is mainly the difference of vegetative growth period.
there are only two forms of incomplete leaf and complete leaf in rice leaf.
the fundamental difference between early rice and late rice lies in their response to temperature.
the growth period of rice varieties increased with the elevation.
potato and solanum tuberosum are two other names of potato.
potatoes originated in china.
potatoes like warmth.
china was the world's largest producer of cotton in 2018.
the vegetative growth of cotton is the basis of reproductive growth.
the main component of cotton fiber is cellulose.
the maturity period is the period during which cotton consumes the most water during the growth period.
rapeseed is not only an important source of edible oil and protein feed, but also an important industrial raw material.
millet is a frost resisting crop.
millet is drought tolerant.
millet is a c4 crop with high net photosynthetic intensity.
sorghum has a strong drought resistance, not only can resist soil drought, but also can withstand atmospheric drought.
sorghum is a light-loving crop. during the growth and development process, sufficient light conditions are required.
corn first originated in china.
sweet corn is generally used as fresh food and canned.
the main function of corn leaves is photosynthesis.
the country with the highest yield of corn in the world today is china.
maize plants have less leaf hair on the surface of the basal leaves.