If it weren't for Xiang Yan being an obvious oriental face, all the Persian envoys would have suspected that Xiang Yan was born and raised in Persia.

Otherwise, how can you be so clear about what Da Zhou doesn't have at all?

And that's not just a simple way to know the crop.

The things he said didn't even know the Persian officials.

After all, they don't go down to the ground to plant and harvest it themselves.

Xiang Yan's detailed cognition sounded like he had planted it himself, planted it for many years, and carefully observed and studied it in the process of planting.

Seeing that Xiang Yan knew the fresh seeds brought by the Persian officials, Zhao Longji also asked with interest:

"Why, the virtuous son-in-law knows this thing? What's the use of it, how do you look quite happy. ”

Xiang Yan looked at Zhao Longji excitedly:

"Your Majesty, with this thing, I can raise at least half more of the population in Da Zhou!"

Corn has strong drought tolerance, cold tolerance, barrenness tolerance and excellent environmental adaptability, and has high nutritional value.

Corn is an important source of feed for animal husbandry and animal husbandry, and is also one of the indispensable raw materials for food, medical and health care, and chemical industries.

Corn straw as livestock feed is one of the most efficient ways to use straw, and can bring certain economic benefits.

Manure, a by-product of corn stover processing and used as feed, is a good raw material for farmland.

The direct use of straw resources to produce biogas can effectively alleviate the problem of rural energy shortage.

Listening to Xiang Yan say this.

Not only Zhao Longji was surprised, but the Persian officials were even more surprised!

Some of these things that Xiang Yan said didn't even think of the Persians!

If this knowledge is transmitted back to Persia, perhaps it will be praised and rewarded by the king of Persia!

I didn't expect that the envoy Da Zhou would have such an unexpected joy.

After seeing the corn, Xiang Yan's interest was also aroused, and she hurriedly went to see the third and last cloth bag on the table.

Sure enough, the contents of this bag did not disappoint Xiang Yan.

"Sweet potato!"

"That's a good thing!"

It is more than 2 meters long, lying on the ground obliquely, the leaves are usually broadly ovate, 4~13 cm long, 3~13 cm wide, the corolla is pink, white, lilac or purple, bell-shaped or funnel-shaped, 3~4 cm long.

The capsule is ovate or oblate.

There is a pseudoseptum, divided into 4 chambers, with underground tuber roots, the tuberous roots are spindle-shaped, and the outer skin is earthy yellow or purplish-red.

It likes temperature, is afraid of cold, is not cold-tolerant, likes light, and is a crop that is not tolerant to shade.

The tuber root is "as big as a fist, the skin color is vermilion, the heart is crisp and juicy, it can be eaten raw and cooked, the yield is high, and the wide variety is barren".

Adaptable, no place is not suitable.

The yield is so high, "dozens of stones per acre, twenty times better than the seed valley"!

"Twenty times!"

Zhao Longji was frightened by this number.

"Son-in-law, are you telling the truth? Is there really such a terrifying yield? ”

Xiang Yan is categorical:

"It's true, it's true!"

At this time, even Zhao Longji's face showed joy.

Xiang Yan continued.

In addition, "moist and edible, or boiled or ground into powder, raw food such as arrowroot, cooked food such as honey, taste like water chestnut", presumably it will soon be popular all over the country!

"After the floods in the south of the Yangtze River, we have not completely shaken off the impact of the lack of harvest and the displacement of hungry people. The appearance of sweet potatoes is undoubtedly the dawn of Jiangnan's rapid recovery! ”

"And sweet potatoes are also a longevity food."

Its function is to quickly neutralize the acids produced in the human body by rice, noodles, meat, eggs and other foods, maintain the weak alkaline balance of the human blood, and convert the carotene ingested into the human body into vitamin A.

Whether it is raw or cooked sweet potatoes, there is mucin. And this mucin is a mixture of polysaccharide proteins, which are collagen and polysaccharide substances.

It can effectively prevent the deposition of fat on the cardiovascular wall, maintain and increase the elasticity of the arterial blood vessel wall, reduce the accumulation of subcutaneous fat, and prevent the atrophy of connective tissue in the liver and kidney.

It can also prevent fatigue, restore energy, prevent constipation, and strengthen longevity.

"In addition, sweet potatoes also have the effects of replenishing deficiency, invigorating qi, strengthening the spleen and stomach, and strengthening the kidney and yang."

It can treat dysentery, diarrhoea, damp heat, pediatric chancre and other diseases.

The milky white slurry in raw potato wedges is a good medicine for laxative, blood circulation and inhibition of muscle spasms.

It has a special effect on the treatment of eczema, centipede bites, shingles and other diseases.

The method is to mash the raw potato pieces, squeeze the juice, and apply them to the affected area, which can be cured several times.

"Sweet potatoes are all over the body as a high-quality feed for fattening pigs."

It can be eaten on its own or mixed with other grains, such as corn, barley, or grass and leaves.

Leaves and vines can be eaten fresh, but also dried and crushed, scalded and boiled with grain bran.

Pig body shape (skeleton elongation) or 1 month before slaughter, eat cooked potato pieces alone or mixed with corn, the effect of fattening and strengthening is particularly good, just like the use of "fertilizer", generally 0.5-0.8kg of meat per day.

However, it is necessary to avoid eating potato nuggets from black spot disease to prevent fat pigs from being poisoned and dying.

"It's just that there are a few taboos about eating sweet potatoes."

The latter words were addressed to the Persian envoys, and they were also regarded as a kind of gratitude for their introduction of the Great Zhou to sweet potatoes.

Eating cold sweet potatoes is easy to cause stomach and abdominal discomfort. Sweet potatoes produce acid in the stomach, so patients with stomach ulcers and hyperacidity should not eat them.

Rotten sweet potatoes (sweet potatoes with black spots) can be poisoned and inedible.

Sweet potatoes contain "gasification enzymes", don't eat too much at a time, and eat them with rice noodles, and eat them with pickles or drink some vegetable soup to avoid heartburn, spitting sour water, bloating and gas.

"There are also a few things to pay attention to in the growth habits of sweet potatoes."

Sweet potatoes are warm-loving, cold-tolerant, and not cold-tolerant, and the suitable growth temperature is 22-30 °C, and the growth stops when the temperature is lower than 15 °C.

The temperature of the budding stage should be 18-22 °C, and the temperature of the germination period will affect the germination rate.

The temperature at the seedling stage should be 22-25 °C, the stem and leaf stage should be at 22-30 °C, and the temperature at the stem and leaf stage should not be lower than 16 °C, otherwise it will hinder its growth or even stop growing.

If it is lower than 8°C, it will cause the plant to wither and die after frost.

The temperature of the root stage should be 22-25°C. The right temperature can promote the good growth of plants in each growth period, and ensure the rapid number and expansion of roots.

As for the problem that the Persians couldn't understand Celsius and had no way to measure the temperature, Xiang Yan didn't think much about it.

After all, if this knowledge is told to them, even if it is limited by technology and conditions, Xiang Yan believes that they should be able to find a way to use this knowledge.

Sweet potatoes love light and are short-day crops. In the process of plant growth, the light energy requirement is high, and it is a non-shade-tolerant crop, and the longer the light energy time is from the stem and leaf stage, the longer the growth period, the higher the photosynthetic efficiency, and the opposite will reduce the photosynthetic efficiency and affect the plant growth.

The sunshine time should be four to five hours a day, sufficient light can not only promote flowering and the formation of roots, but also make more nutrients accumulate on the roots and promote the expansion of roots.