HYBRID SEED PRODUCTION BASICS

Hello friends, welcome back to my youtube channel journey with Vijay Kumar Srivastava. Today we are going to study the topic hybrid seed production basics. Before presentation, I would like to introduce myself. I am Vijay Kumar Srivastava. I have done MS agriculture with a specialization in agronomy from J.B.Pant University of Agriculture and Technology, Pantnagar in 1996 and presently associated with seed industry. So let's proceed to the presentation. What is hybrid seed? The seed F1 generation produced from a cross between genetically dissimilar parents and the hybrid bigger or heterosis is the absolute phenomenon where expression of the characteristics such as growth related traits flowering and yield fall outside the range of its parents with superiority. Hybrid is produced by crossing between two or more genetically dissimilar parents. Pollen from male parent which is pollen parent will pollinate fertilize and seed sets in female which is seed parent to produce F1 hybrid seeds. For production of a hybrid crossing between two parent is important. The crossing process will result in heterosis. In self-pollinated crops, it is difficult to cross but in cross-pollinated crops, it is easier. Cross-pollination results in genetic heterogeneity and so wider adaptations. Now to study the desired traits of hybrids. Hybrids are having the some characteristics by which it is familiar. It is beneficial to the farmers like better yields, greater uniformity, improved quality, disease resistance, insect pest resistance and wider adaptations. In case of field crops, the hybrid seeds are popular in crops like maize, corn, sorghum, pomegranate, rice, cotton, sunflower, safflower, pigeon pea, castor and mustard. In hybrid seed production, two parents are used like first female parent which is CMS line A line and second is male restorer R line. In hybrid seed production of some crops like maize, corn, pomegranate, sorghum, rice, mustard, sunflower, castor, sorghum, sorghum sudangrass, female parent A line is esterile plant. In case of maize, female detaching is done to make female esterile. While in some crops like cotton, okra, chili, tomato, we have to follow emasculation process to make female esterile. To get best hybrids, two points are very very important in hybrid seed production. First, CMS A line means female desirable characteristics and second, restorer line R line desirable characteristics. Desirable characteristics of A line female can be described as a stable and complete male esterility, good out-crossing ability, good combining ability, desirable traits, high seed yield and good seed characteristics. Restorer male line plays an important role in increasing heterosis as well as increasing hybrid seed yield in seed production plots. The desirable traits of R line like first, a strong and stable fertility restoration over seasons and locations, highly vigorous plant growth habit with tall plant height, good pollen production, long shading period, complete desiccant of anthers and high amount of residual pollen, multiple disease and pest resistance and good out-crossing and combining ability. Now we will go through prerequisites for a good hybrid production. It refers to the optimum conditions which are needed like first one, a stable cytoplasmic genetic male esterility system, adaptability across environments, perfect synchronization flowering between male and female parents, height of the male and female parents, stigma receptivity and pollen dispersal, ease in production, high and economical seed yields and high level of yields on commercial scale crop. Here we have represented the hybrid seed production process in maize crop. Here we are using R line and A line. The female to male sowing ratio generally vary from 4 is to 1 to 6 is to 2. In case of female de-tasseling process is done to make female sterile. De-tasseling is a process of removal of tassels from female plant. Male parent is fertile and the out-crossing takes place through wind movement and the crop pastages vary from sowing to vegetative to bootleaf pastage. In bootleaf pastage we have to do de-tasseling process. After that there will be flowering, cross-pollination will take place, seed development and after that there will be maturity and harvest. After crossing over we have to harvest male first and it should be removed from the field and the seed parent female parent is used for harvesting as a F1 hybrid seed and this harvested seed is used for commercial cultivation. Here we have shown the mechanism of hybrid seed production in rice. Here also R line and A lines are used and the generally female to male row ratio is followed 6 is to 2. Female is a sterile parent and male is fertile and out-crossing takes place through wind movement. In case of rice the pollen is bulky. So supplementary pollination is followed to maximize the out-crossing and the various stages of seed production of crops are nursery raising of both male and female parents after that transplanting, bootleaf pastage, flowering stage, then cross-pollination, seed development and maturity to harvest. Male is harvested first just after completion of flowering and male should be chopped out and at last after female seed parent maturity, we have to harvest separately and this female seed parent harvesting seeds will be treated as F1 hybrid seeds which is used for commercial cultivation. Here we have shown the hybrid seed production of millet. Here also R line and A lines are used and the female to male row ratio is generally followed from 8 by 2 to 12 by 2 depending upon the floral behavior of parents. Female parent is sterile and male is fertile and the out-crossing cross-pollination takes place through wind movement and there are various crop stages from sowing to harvest like sowing to vegetative then bootleaf pastage, flowering stage, cross-pollination, seed development stage and maturity and harvesting. Here also just after pollination completion we have to harvest male. It should be chopped out and should be removed from field and at last the female seed parent is harvested and this harvested produce will be used as F1 hybrid seed and this is distributed for commercial cultivation. This is about sorghum hybrid seed production. The production method is common where the crossing between A line and R line takes place to develop F1 hybrid seed and here also female is sterile and male is fertile and out-crossing takes place through wind movement and the female produce harvested produce will be used as F1 hybrid seed. Here we have represented mustard hybrid seed production. In case of mustard seed production also male sterile line R and female sterile line A lines are used and the row ratio is generally followed 6 by 2 or it may vary depending upon the floral behavior of both parents. Female is sterile male is fertile and the out-crossing takes place through honey bees. In case of mustard the pollen is bulky heavy so movement is a problem. So in this case, we are generally using bee hives and the because of movement of honey bees from male parent to female parent because of attractive yellow flowers cross-pollination takes place and it will result in significant improvement in yields. And there are various crop stages like sowing, vestative stage, flowering stage, cross-pollination stage after that silica formation then seed development and maturity and harvest stage. In case of mustard also just after completion of pollination the male should be chopped out. It should be removed from field and at last maturity female is harvested and that seed parent female harvested produced is used as F1 hybrid seeds, which is used for commercial cultivation. In case of castor hybrid seed production also A line and R lines are used and the generally row ratio is followed a 3 by 1 and the isolation distance is needed 300 meters to avoid any contaminations. Now we will study about cotton hybrid seed production. Here also female A lines and male R lines are used but in cotton the production method is differing from other crops. Here female and male parents are sown in separate isolated blocks instead of row arrangement. Female and male plant population ratio is generally maintained 75 by 25 and there is emasculation and hand pollination practice in cotton hybrid seed production where the emasculated female stigma is crossed with male pollen. So after cross the harvesting of female produce will result as a F1 hybrid seed and here also after completion of crossing pollination the male should be removed and the female produce is used as a hybrid seed. Next is sunflower hybrid seed production here also A line and R lines are used. A line is a straight line which shows no pollen production and R line is having the pollen production capacity. In case of sunflower female and male parents are sown in separate isolated blocks and the female to male plant population ratio is generally maintained 75 by 25. As the crossing method is concerned in case of sunflower also hand pollination method is followed. First male pollen is collected separately and this pollen is used to cross pollinate female. Female head is crossed manually by hand pollination method with collected male pollen powder using cotton cloth or puffs which is gently rubbed on the female heads. In female the stigma opening takes a cycle of 15 to 20 days and stigma opening takes place from outer sides. So every day we have to pollinate the stigma of the female head and the crossing will take 10 15 to 20 days period. Here also after pollination the male line should be harvested and it should be separated from the field and after maturity of female crop this is harvested separately and this harvested produce will be used as hybrid seed. In hybrid seed production there are some important practices about which we will study here. Like first one is a staggering. A staggering refers differential showing of male and female parents means difference between showing dates of both parents to achieve proper synchronization of flowering of both parents during hybrid seed production. A staggering depends on flowering behavior of both male and female parents. The parents which is having the nature of long duration to take flowering stage should be planted early and the parent which is having less duration requirement to reach flowering stage should be planted later. So the aim of a staggering is to match the nicking of both parents. Then seed rate The number or quantity of seeds planted per unit of area in acres or hectares to ensure optimum population for maximum yield is called seed rate. Female seed rate is higher than male as generally female and male plant population ratio is 80 to 20 in case of wind pollination crops and 75 by 20 in manual pollination crops. Then spacing which refers planting or showing of seeds maintaining desired distance between row to row and seed to seed. Now planting ratio or row ratio. It refers to the showing arrangement of rows of female and male parents. Example 4 is to 1 means four lines of female and one line of male. Planting ratio or row ratio is followed in hybrid seed production where two parents are used male and female. This is depending on growth and flowering behavior of both parents and aim to get maximum yields. Depending on floral behaviors the row ratio can be altered. In some crops like cotton and sunflower female and male parents are shown in separate isolated blocks instead of row arrangement. Generally female and male ratio is maintained 75 by 25 where male population should be adequate to supply pollen to female for crossing. Isolation is one of the important parameter in seed production to achieve the best quality. There are isolation standards varying from crop to crop and for best genetic purity it should be complied strictly where isolation is the state of being in a place or situation that is separate from others. In seed production one field separated from another field of same crop with different variety. What is the isolation distance? Isolation distance is the minimum separation required between two or more varieties of the same species of the crop for the purpose of keeping seed pure and to avoid contamination. In hybrid seed production if there is female contamination with foreign pollen or physical admixture, it will result on impact of hybrid performance. The isolation is of three types. First one is distance isolation or special isolation to be maintained recommended isolation distance as per the crop standards. Second is time isolation or temporal isolation to be followed to escape flowering simultaneously within seed and other plot and third is physical barrier isolation where the topographical surface features natural obstacles, tall crops or artificial obstacles are used. Now to study about distance or special isolation the special separation required between a seed field and other sources of genetic and physical contamination especially between varieties of cross-pollination. In case of a special isolation, there are three parameters like first more the extent of out crossing wider the distance means depending upon the crossing nature the crop to crop the distance will vary. The crop having maximum out crossing needs more distance like in case of corn the isolation distance is varying from 250 to 400 meters. In case of perl millet it is 200 meters, in case of sorghum it is 100 meters, in case of rice it is 100 meters, in case of sunflower the isolation distance is 1000 meters, in case of mustard 1000 meters and in case of castor 300 meters. So depending upon the crop nature we have to follow these minimum isolation criteria. Second higher the class of seed wider the distance like in case of breeder seed which needs higher purity the the isolation distance will be more than foundation seed. While in case of foundation seed the isolation distance will be greater than certified seed. So as the class is high there will be more isolation distance. Third is in hybrid seed production wider the distance than that of variety. In case of hybrid seed production the isolation distance requirement is more compared to varietal seed production. Second type of isolation is time or temporal isolation. Crop of seed production should be sown early or late by margin of 20 to 30 days depending on parent nature then neighboring fields of same crop of other variety to avoid same time flowering and to prevent entry of foreign pollens in the field of production. So the main aim is to avoid the flowering of same time or overlapping of flowering which may cause contamination. Third type of isolation is physical barrier isolation. In surrounding of crop of seed production particularly on bunds crop of well plant height and densely planted should be grown to prevent entry of foreign pollens in the field of seed production. Means this is the method where the barriers are used like plant hedges or tarpaulins or other physical methods to avoid contamination from foreign pollen. Other practices are roguing which refers to the act of identifying and removing plants with undesirable characteristics from agricultural or seed production fields. Rogues are removed from the fields to preserve the quality of the crop being grown. Then synchronization or nicking. Simultaneous flowering of male and female parents in hybrid seed production is known as synchronization or nicking. Synchronization in flowering between the parental lines assumes greater importance as the seed set on female parents depend on the amount of pollen supplied from the male parent during flowering period. So nicking and synchronization is very very important to get the optimum yields. After that flowering which refers to the full blooming of the reproductive parts of the plants where pollen moves from male organ to female stigma for pollination. In hybrid seed production another process is emasculation which refers to the removal of male organs estamans or anthers or killing the pollen of a flower without damaging the female reproductive organ. In bisexual flowers emasculation is essential to prevent of self-pollination. In some crops hybrid seed production like cotton, okra, chili, tomato etc. emasculation process is followed to make female sterile. Then pollination. The movement of pollen from the anthers to the stigma by wind is known as pollination. Female stigma is essential for seed set and therefore crucial in seed production. In case of hybrid seed production pollen transfer from male plant to female plant stigma takes place and cross pollination through wind blowing like in crops corn, perl millet, sorghum, rice is taking place. After that hand pollination or manual crossing method. In case of some crops like cotton, sunflower and vegetables there is pollination done by hands using levers instead of wind pollination. Harvesting. In case of hybrid seed production first male parents should be harvested and completely taken out from fields. After thorough checking then female parents should be harvested. This harvested produce is treated as F1 hybrid seed. Then post harvest and processing. After harvesting there will be various plant processing activities as threshing, drying, mechanical cleaning, specific gravity cleaning, seed treatment, packing, distribution placement and finally sales of the produce of hybrid seed. So this presentation was all about hybrid seed production basics and hybrid seeds. Hope this will be very very useful to all of you. Now my presentation ends here. I have given here my youtube channel details journey with Vijay Kumar Srivastava. Having request please visit the channel subscribe it and provide your kind and valuable feedback for further improvements in next coming presentations. Thank you.