How to save hybrid rice? What hinders development?

The data show that in recent years, the declining trend of hybrid rice varieties is very obvious. the number of varieties with an annual extension area of more than 1 million mu has increased from 46 in 2002 to 59 in 2004 and then decreased to 29 in 2012. The number of varieties with an annual extension area of more than 5 million mu has decreased from about 9 in the early stage to 1 per year at present, and there have been no varieties with an annual extension area of more than 10 million mu since 2007. The average annual extension area of the main popularized varieties of hybrid rice decreased significantly from 2.133 million mu in 1993 to 374000 mu in 2012, with a decrease of 82.5%.

"Save hybrid rice!" It is the proposal that the reporter heard most at the demonstration meeting of "C Liangyou Huazhan" varieties in the upper reaches of the Yangtze River on August 26. In fact, as early as three years ago, Professor Chen Liyun of Hunan Agricultural University issued an appeal to save hybrid rice: to take saving hybrid rice as a major issue to solve China's food security and save the national seed industry.

"rescuing hybrid rice is a systematic project, which is beyond the reach of several people and units. It is necessary to have policy support; to identify the problems that hinder the development of hybrid rice and the technical keys to solve them; to carry out multi-disciplinary collaborative innovation; and to strengthen the close cooperation of multi-sectors and multi-industries, under the framework of top-level design, each does its own thing. " Chen Liyun said, "only in this way can hybrid rice regain its youth."

What hinders development?

The advantages of the past turned into disadvantages.

In the past, the successful application of hybrid rice in China is mainly attributed to the yield advantage (generally increasing by more than 10%), the seed price advantage (the seed price per kilogram of hybrid rice was less than 12 yuan before 2008), and the seedling raising technology advantage (the field seed quantity of hybrid rice is only 10% and 20% of that of conventional rice).

Nowadays, with the continuous improvement of the breeding level of conventional rice with high quality and high yield, the yield difference between hybrid rice and conventional rice is narrowing, and the yield of some high-yielding conventional early rice varieties planted in production is close to the level of early hybrid rice. due to factors such as the sharp increase in labor prices, the high price operation of seed companies and the high R & D costs of seed enterprises, the seed price of hybrid rice is about 10 times higher than that in the early stage of development. With the rapid popularization of direct seeding and mechanical transplanting, the planting density of raising seedlings is high, and tillering will not be produced in the seedling raising period. it is necessary to increase the amount of seeds used to ensure the basic seedlings, resulting in a doubling of the amount of seeds used in the field of hybrid rice, resulting in the continuous reduction of the planting area of hybrid rice.

Lack of varieties suitable for large-scale production

Direct broadcast, machine insertion and machine collection are the main technologies of large-scale production. The biggest advantage of direct seeding is its low cost, saving more than 200 yuan per mu; although the production cost of transplanting rice seedlings by machine is about 100 yuan per mu more than that of direct seeding, the grass damage is well controlled, which can alleviate the seasonal contradiction to a certain extent, and the yield can be increased by prolonging the growth period of varieties, which is the key development direction in the future.

However, the biggest changes in the characters of hybrid rice required by direct seeding and mechanical insertion were the increase of seed use in the field and the shortening of growth period. In the case of wheat stubble rice, the growth period of varieties is usually 5-10 days shorter than that of traditional transplanting methods; if double-cropping rice is double-cropping rice, the growth period of early rice varieties is 5-8 days shorter than that of mid-maturing late rice varieties such as Wufengyou 308.

The biggest change of mechanical harvest on the characters of hybrid rice is the strong lodging resistance, especially the lodging resistance of direct seeding rice. Once the variety lodging, in addition to the yield and quality affected, machinery can not be harvested, each mu will increase the cost of manual harvesting of more than 200 yuan. With the popularity of machine harvest and the rise of wages, the lodging resistance of varieties has become the preferred character of farmers.

The improvement of the degree of mechanization in modern agricultural production shortens the growth period of hybrid rice, resulting in a decrease in yield, an increase in seed consumption and a poor benefit of planting rice.

How to improve the competitiveness?

Modern agriculture has put forward higher requirements for hybrid rice, but the urgent task is to reduce the seed price of hybrid rice, cultivate varieties with suitable growth period, and greatly improve rice quality without affecting yield.

Lowering the price of seeds is the last word.

"Farmers want less input and more output. In the final analysis, the price of seeds should be low." Chen Liyun said, "at present, it seems to be effective to reduce the seed price of hybrid rice by relying on scientific and technological progress."

The seed production yield and seed commercial value of hybrid combinations were greatly improved by breeding parents with ultra-high outcrossing seed setting rate. The rice dual-purpose genic male sterile lines Chuang 5S (Qiongshendao 2013020) and Yun 9s (Xiangshendao 2012022) bred by Chen Liyun have excellent agronomic characters, and their sink capacity is close to that of the control hybrid rice in the regional test, so they have the potential of super high yield in seed production. The stigma exsertion rate is high, vigor is strong, compatibility is good, and the outcrossing seed setting rate can reach more than 75% when the parents meet at this flowering stage. Flowering habits are little affected by abnormal weather, in high or low temperature conditions, there will not be a large number of glume closure; not easy to sprout on the ear; seeds do not split glume or rarely split glume, seed bud rate is high and stable. Compared with the rice dual-purpose genic male sterile lines currently used in large-scale production, the yield of seed production can be increased by more than 30%.