2. 2-row vs. 6-row http://barleyworld.org/FAQ_sheet.php
What is the difference between a 2-row and 6-row barley?
This is a story of seeds, heads, history, and perception. 2-row barley has 2 rows of seed on each spike (head) and 6-row barley has 6 rows of seed on each spike (head). Botanically speaking, a 2-row has 1 fertile floret per rachis node and a 6-row has 3 fertile florets per rachis node. Two genes control the trait: VRS1 and INT-C.VRS1 is cloned and the cloning of INT-C will soon be announced. Wild barley is 2-row. The 6-row trait was selected shortly after domestication. The current geographic distributions of 2-row and 6-row (and perceptions regarding their suitability for different end uses) are largely accidents of history.

3. Winter vs. Spring http://barleyworld.org/FAQ_sheet.php
What is the difference between winter and spring barley, and what the *%^&(+ is a facultative barley?
The three growth habit classes of barley are winter, facultative and spring. A winter barley is planted in late fall and is harvested the following summer. A spring barley is planted in the spring and harvested the same summer. If you plant a winter barley in spring, it will not flower, or it will flower too late. If you plant a spring barley in the fall, it will (in many temperate environments) die from low temperature injury. A facultative barley can be planted in the spring or the fall, and it is cold-tolerant. There are three principal physiological traits involved: vernalization sensitivity, photoperiod sensitivity, and low temperature tolerance. Vernalization sensitivity means the plant needs exposure to low temperature before it can flower. Winter barleys are vernalization-sensitive whereas facultative and spring types are not. Photoperiod sensitivity means the plant will not flower until the day length reaches a critical threshold. Many winter barleys, most facultative barleys, and few spring barleys are sensitive to short days. Low temperature tolerance is an induced trait. Winter and facultative barleys are more cold tolerant than spring barleys. Since the traits are controlled by different genes our bets are on photoperiod-sensitive, cold-tolerant facultative varieties.

4. Malt vs. Feed http://barleyworld.org/FAQ_sheet.php
Why some varieties are better for making beer than others
Barley malt is the perfect combination of starch, enzymes, flavors, and aromas for brewing, distilling, baked goods, cereals and confections. There are many types of barley malt – from light to dark – but all are variations on two principal themes: germination and kilning. Different end-uses require different malt quality specifications. Some of the principal characteristics used to define malting quality are protein (low, moderate, or high), malt extract (high), enzyme activity (moderate to high), and beta glucan (low).
Feed barley is used as food for animals. Varieties also differ in their feeding properties but unfortunately feed barley is simply sold by the ton. Feed barley prices are often so low that farmers grow other crops - if they can do so. As a consequence, barley’s adaptability to extreme climates makes it an important feed grain only in areas where it is unprofitable to grow (or import) maize.
Hooded barley is a unique type of feed barley that has hoods, rather than awns. These types are usually cut green for hay or silage. The lack of awns allows for easy chewing by the animals.
Malt
Feed
A rule of thumb is that good malt barley is good feed barley, but not the reverse. In general, malt barley commands a premium over feed barley, but yield less.  
Many genes determine malting and feed quality; two genes determine the hooded trait.
Forage

5. Malting barley variety development
Grain to Glass 11 – 13 years
Time frame
(yrs)
Activity
Amount of seed required for one malting quality assessment
Amounts of seed available and scale
2-3
Breeding and selection; initial agronomic assessment
Segregating generations
Doubled haploid populations
0g – 1 kg for breeding program
3-4
Preliminary to advanced agronomic testing and micro-malting of samples from multiple environments
200 grams
1 kg – 20 kg for breeding and extension programs
20 kg –100 kg for breeding and extension programs. Initiate large-scale increase of pure seed for commercial scale quality assessment and variety release 3
AMBA Pilot Scale Test must be rated satisfactory in 2/3 years of testing
7 kilograms/
location
2 locations
Large volumes for on-farm testing and commercial scale malting and brewing
AMBA Plant Scale malting and brewing trials must be rated satisfactory in 3/3 brewing trials
800
metric tons 3

6. Hulled, Hull-less, and Pearled Barley Foods
Barley grain comes off the plant in two “styles”: with adhering hulls and without adhering hulls. One gene (NUD) determines whether or not the hulls (lemma and palea) adhere to the grain. If the hulls adhere, the barley is (correctly) termed “hulled”. Most barley varieties in most of the world are hulled. The hulls can be removed by vigorous mechanical abrasion, in which case the barley is “pearled”. If the hulls do not adhere, the barley is said to be hull-less (or naked). Hulled, pearled, and hull-less barley grain all contain beta-glucan, a source of soluble dietary fiber that is responsible for lowering cholesterol. The Food and Drug Administration (FDA) ruled in 2006 that barley foods may carry a health claim specific to soluble fiber and coronary heart disease. Qualifying products may use the following claim: “Soluble fiber from foods such as [name of food], as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease. A serving of [name of food] supplies [x] grams of the soluble fiber necessary per day to have this effect.” Pearled barley has about the same cooking time as rice. Hull-less barley requires twice the cooking time (and liquid) as pearled barley.