Detailed Explanation of Key Techniques for High-Yield and High-Quality Cultivation of Black Rice

Black rice is an ancient and precious rice variety in China. It is rich in nutrients and has the functions of nourishing yin and replenishing blood, darkening hair and preventing aging. It has always been eaten as a tonic, and among the people it has the fine names of blood-nourishing glutinous rice, bone-setting glutinous rice, medicinal rice, longevity rice and monthly rice (eaten by women during confinement). Black rice is mainly distributed in Yunnan, Guizhou, Guangdong, Guangxi, Hunan and Shaanxi provinces. In the long course of cultivation, many precious farmer varieties have been formed, such as Yunnan Jinggu purple rice, Guizhou Huishui black rice, Guangxi Donglan ink rice and Hunan southwestern Hunan black glutinous rice. However, these varieties generally have tall plants, loose plant type, drooping leaves, long panicles with sparse grains, are not resistant to disease, are prone to lodging, and yield only 100-200 kg per mu (1 mu = 667 sq m, the same below).

In recent years, through methods such as systematic selection and breeding, radiation mutation and hybrid breeding, a number of dwarf, high-yield black rice varieties have been developed, such as Aixuenuo, Zixiangnuo, Xiangxuenuo, Zaoheinuo and Longqing No. 4. As long as cultivation methods are appropriate, the yield per mu can reach 300-450 kg, or more, and they are now planted on a large scale. To further develop black rice, its high-yield and high-quality cultivation techniques are introduced as follows.

(1) Sow early at the right time: Because black rice is a temperature-sensitive variety, sowing is required from March 10 to 15. This can extend its growth period and allow it to head, flower and pollinate before the arrival of high temperatures in late July, which helps increase yield and rice quality.

(2) Dry-raised strong seedlings with many tillers: Around the field, choose a plot (block) of sandy loam field or dry land that is sheltered from the wind, faces the sun and has convenient drainage and irrigation for film-covered dry seedling raising. Sow appropriately sparsely, sowing 4.5 kg per mu of seedling field, and the seed rate per mu of main field is 1.5 kg.

(3) Improve transplanting quality: Use an east-west orientation, wide rows and narrow plant spacing, and transplant large seedlings with soil. Plant enough basic seedlings per mu of main field, 300,000-320,000, so that they no longer tiller. The plant and row spacing for wide rows and narrow plant spacing is generally 10 cm x 22 cm. This can increase ventilation and light penetration, help healthy growth, produce large panicles with many grains, and improve rice quality.

(4) Apply more phosphorus and potassium fertilizer, and apply little or no lime: According to soil survey data, the available potassium content of general soil is relatively low, and phosphorus content is also very low in some areas. Therefore, increasing the application of phosphorus and potassium fertilizer is an important measure to improve the quality of black rice. Phosphorus fertilizer is mainly applied as base fertilizer, potassium fertilizer is mainly applied as a top dressing combined with the first cultivation, with a small supplementary application at the booting stage, and both phosphorus and potassium fertilizers can be sprayed on the leaves before and after heading. If black rice absorbs too much calcium, the cooked rice appears coarse and tastes poor. Therefore, fields cultivating black rice should apply little or no lime.

(5) Use as little pesticide as possible or none at all: Pesticide residues harm the health of humans, livestock and poultry and reduce the quality of black rice. Therefore, in pest and disease control, comprehensive control measures based mainly on agricultural control should be adopted, including selecting disease- and pest-resistant varieties, treating diseased rice straw, removing debris, shallow irrigation and exposing the field, drying the field at the right time, thoroughly removing barnyardgrass, and using local methods and local medicines to control pests and diseases, so as to achieve the goal of controlling and eliminating pests and diseases without pesticide residues.

(6) Do not cut off water too early in the later stage: If water is cut off too early during the maturity period of black rice, it will not only increase the rate of empty grains and reduce the 1000-grain weight and yield, but also affect the quality of black rice. Generally, black rice should have water cut off about 6 days before harvest.

(7) Harvest early at the right time: If black rice is harvested too late, the cooked rice will have no fragrance, and the grains will be both coarse and hard. Therefore, harvest when 85% of the rice grains are mature.

(8) Pay attention to improving the method of drying rice: If black rice is exposed to the hot sun after harvest, rapid dehydration and drying will increase the broken rice rate during milling. Therefore, at the beginning of drying, it can generally be spread 7-10 cm thick, and turned frequently to prevent excessive dehydration. In particular, do not spread it on cement ground for exposure to the sun.

(9) Accelerate propagation and continuously purify and rejuvenate: Black rice varieties are very precious. To accelerate breeding, sow sparsely to raise strong seedlings. When the seedlings have 7-8 tillers, the tillers can be separated one by one and transplanted as single plants. In this way, 100 g of seed can plant 1 mu of main field. Before harvest, select 30-40 grains from the upper part of the main panicle (that is, seeds from the strongly hereditary part) that have the characteristics of this variety, large panicles with many grains, and strong resistance, to use as seed for the next generation seed field or for the seed of a high-yield trial field, so as to continuously purify and rejuvenate, and improve yield and quality.