In gymnosperms the cone is the female reproductive part and the pollen is the male reproductive part. Pine trees and other gymnosperms produce two types of cones. The male cone is called the pollen cone. ... A single tree usually produces both pollen and seed cones.
Yara Crop Nutrition
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Agronomic Principles
Crop Characteristics
Potatoes produce a fibrous root system. These roots are at best no more than 24in long. Thus potatoes are shallow rooted compared to cereals for example, which can root to at least 47in depth. As a result, potatoes are often unable to exploit nutrients and soil moisture at depth within a soil profile.
While root growth occurs when soil temperatures are between 50 to 95˚F (10 to 35˚C), best, most active root development is at soil temperatures of between 59 and 68˚F (15 and 20˚C).
Leaf (haulm) growth occurs at temperatures of between 44.6 to 86˚F (7 to 30˚C) , but optimal growth is at around 68 to 77˚F (20 to 25˚C). Optimum temperatures for stolon growth are similar.
effects of soil temperature on root development
The potato tuber is an enlarged portion of the stolon. The initiation of this tuber is triggered by short day lengths (photoperiods), and involves growth hormones. The colder the soil temperature, the more rapid the initiation of tubers and the greater the number of tubers formed. The optimum soil temperature for tuber initiation is 59 to 68˚F (15 to 20˚C).
Under these conditions, the potato plant will have short stolons and shoots. Longer day lengths delay tuber initiation and favor the growth of the stolon and shoot. High temperatures also reduce tuber formation. Late varieties seem to be more sensitive to long day lengths or high temperature conditions.
Low nitrogen and high sucrose levels in the plant favor the formation of more tubers.
Once formed, tubers grow rapidly, reaching a maximum rate of up to 1,249 lb/ac/day in temperate climates. See figure below:
potato tuber growth rate, germany
Physiological Aging
By planting sprouted seed, crop growth can be advanced. The magnitude of this response and its effect on increasing crop yield is related to the physiological age of the seed at planting.
Answer:
Cell membrane
Explanation:
Cell membrane is an important part in cell which performs various vital functions. It is not only a simple boundary that surrounds the protoplast rather it is a semi permeable membrane structurally made of proteins and lipid bilayer and regulates the transport of different materials across it.
It regulates the following transports -
- Disposal of wastes
- Export and import of nutrients
- Export and import of various ions
- Export and import of gases
