From Pollination to Prosperity: Factors in Hybrid Seed Production

Hybrid technologies take advantage of Crop plants' heterosis for financial gain. Rice hybrids can yield 20–30% more than HYVs and result from an F1 cross between two pure line genotypes that are genetically distant from one another. Rice is a self-pollinated crop with a natural outcrossing rate of 0.3% and 3.0%. However, a higher outcrossing rate is necessary for hybrid seed production to produce substantial seed yields. As a result, making hybrid rice seed demands specialized methods, which must be fully comprehended before beginning this project. Selection of the field, isolation, timing of seeding, pattern of planting, the weather during flowering, roguing, synchronization of the flowering of the parental lines, supplemental pollination, and post-harvest procedures are some variables that influence hybrid seed production. The current effort intends to provide vital data for effective hybrid rice seed production, which will significantly benefit the organizations or people engaged in such a business. 

Some important factors that influence hybrid seed production

Favourable climate: 

The climate significantly influences the yield of seeds. Setting the seeding dates requires thorough knowledge of the locality's weather statistics. Planning the seeding of the parental lines should ensure that both parents flower during the most favourable environmental conditions. Conditions include the following: 

A daily average temperature between 240 and 30 °C  A relative humidity of between 70 and 80% The temperature differential between day and night should not exceed 80–10 oC (50–7 oC is ideal). Enough sunshine and a wind speed of 2 to 3 meters per second.It shouldn't rain nonstop for three days straight during the flowering time. If the daily mean temperature is between 20 and 35 degrees Celsius throughout flowering, the yield will suffer.

Location selection: 

Since it is well known that producing rice hybrid seeds is laborious, successful seed production requires a specific location with a fertile field, an adequate irrigation and drainage system, enough sunlight during flowering, and no significant disease or insect issues. Therefore, some requirements should be considered while choosing a location for manufacturing hybrid seeds.

Isolation: 

Because rice pollen grains are so small and light, they may move through the air at relatively low wind speeds and travel great distances. The seed production plots should be adequately isolated to guarantee the purity of hybrid seeds and prevent pollination by undesirable rice varieties. Numerous strategies can be used to avoid unintended pollination. These are listed below. 

  Space isolation

By maintaining varieties, planting, and maintaining at least a 100-meter buffer zone between hybrid seed production and CMS line maintenance plots and plots of other crops, varietal contamination in hybrid seed production can be avoided.

  Time isolation

Wherever it is challenging to have a space isolation, a time isolation lasting longer than 21 days might also work, it means the parental lines' heading stage in a hybrid seed production plot should be 21 days earlier or later than other kinds cultivated nearby.

  Barrier isolation

Natural geographical elements, such as mountains, rivers, and woods, can sometimes be the most effective barriers. A 30-metre-long crop barrier made of Sesbania, sugarcane, and maize would also serve as an isolation barrier. An artificial wall of polythene sheets and seed nets around 3 meters high can also be employed for small-scale seed production. But the best places to build are those with hills and mountains, which serve as natural barriers.

Seeding and transplanting

The hybrid rice seed production plot's seeding order for the pollen parent (R line) and seed parent (A string) relies on how long each has grown. Therefore, male parents (B/R line) must be sown at three staggered dates (at 3–4-day intervals) and transplanted following the patterns provided to achieve complete synchronization in parental lines and long-term availability of pollen.

Transplantation: 

It is essential to transplant the parental lines at the appropriate seedling age to guarantee healthy plant growth, full flowering synchronization between parental lines, and increased seed production. When they are between 21 and 25 days old, seedlings from both the A and R lines should be transplanted. Younger seedlings advance in blooming while more aging seedlings delay flowering (transplanting an older seedling can cause a half-day delay in flowering and vice versa). If the 'A' line seedling transplant is delayed, the 'R' line transplant must be postponed by the same number of days.

Roguing  

Hybrid rice seeds must be more than 98% pure for commercial production. The purity of the restorer and CMS lines must be more significant than 99% to achieve this criterion. To ensure complete isolation, it is also required to eliminate all rogues from the seed production plots. In hybrid seed production plots, roguing is the process of removing undesired rice plants. Undesirable rice plants deviate from typical rice plants in A or R line rows. Roguing assists in maintaining the purity of hybrid seed by preventing the off-types from interfering with the plants that are true to the type A-line. After some time, farmers use fertilizers and take care of the rice plant. After getting ripe rice, they harvest it.

Conclusion

The production of hybrid seeds has a positive economic impact while being more labor- and resource-intensive than conventional seed production. It produces more work opportunities and generates more net revenue—hybrid seed costs Rs. 250 and 270 per kg on the market. But unfortunately, the farmers that grow the hybrid seeds only receive Rs. 80–90 per kg. But it is for farmers; we can fill our empty stomachs daily. So, we should respect them.