HYBRID PADDY : GUIDELINES FOR TRIAL SEED PRODUCTION : AK Gupta, Ph.D

These guidelines have been provided to primarily help in successful hybrid rice seed production. Timely operations would help to raise the best crop with proper synchrony of male and female and high seed yield.
Seed Rate: For ¼ ac trail 1.25kg Female and 500g male has been issued, divide male in three equal parts to make three male sowings on different staggered dates.

SELECTION OF FIELD :
The selected fields should have fertile soil, assured irrigation and good drainage system.

NURSERY RAISING :
: ** Female and male nursery should be sown on separate seed beds so as to avoid any chances of mixture.

LAND PREPARATION, FERTILIZATION AND METHOD OF SOWING :
Nursery area should be well puddle (a week before sowing), levelled and kept weed free. It should have adequate water for irrigation and good drainage system.
Provide adequate fertilizer to nursery beds i.e for each 40 sq. metre area of nursery bed, provide 0.36 kg Urea, 0.36 kg DAP and 0.28 kg MOP at the time of sowing.
Soak @ 1 Kg. seed in 1.6 liters of water containing 2 gms of ceresan-wet for 8-10 hours. Pregerminate this wet treated seed by incubating in warm moist conditions for 36-48 hours or until germination.
Broadcast these pre-germinated seeds on drained beds at the rate of 1 Kg seed per 40 sq.metre. It is very important to sow the seed as mentioned above to get healthy seedlings. Thick sowing of seeds would lead to weaker seedlings .
Keep the nursery beds moist, for the first few days. Do not flood the beds. When the seedlings are about 1 inch high, keep the beds submerged in a shallow layer of water.
Top dress the seed beds with 0.28 kg Urea /40 sq. metre area, 10 days before transplanting. Seedlings will be ready for transplanting in about 35 days. Transplant male when 2nd male is 35 day old.
If the seedlings in the nursery show the yellowing to whitish of leaf tips, spray them three times with 0.5 - 1% ferrous sulphate solution 5 gm/ litre.

ISOLATION :

Distance isolation is the best isolation for raising the hybrid seed production plots. An isolation distance of 100 metres is recommended to obtain pure hybrid seed. This means that no other variety of rice should be grown in vicinity of 100 metres except the pollen parent. In cases, where somehow, distance isolation is not available, a minimum of 3-4 weeks time isolation is possible. Care should be taken that the other variety having time isolation should not flower within 3-4 weeks period of the hybrid seed production plot.
ROW RATIO : 2:6 Two rows of male : Six rows of female
ROW DIRECTION :Row direction should nearly be perpendicular to direction of the wind prevailing in the area at the time of flowering to promote out-pollination.
PLANTING PATTERN :
Transplant male seedlings in the main field 35 days after second sowing of male parent in paired rows 15 cm apart. Within a row, transplant single seedling of male nursery per hill in such a way that seedlings of three different ages may alternate each other systematically.
Next set of paired rows of male nursery should be transplanted leaving a gap of 135 cm with the help of planting board, for planting the female seedlings at a later date.
Continue transplanting paired set of male rows throughout the field, following the above pattern.
Keep all extra seedlings of male nursery in one corner of the field for gap filling.
Gap filling should be done within one week of transplanting in the male line after which all remaining male seedlings should be destroyed.
Start transplanting female line 35 days after sowing i.e. after planting the male lines. Six lines of female nursery are transplanted between 2 sets of rows in such a way, that outer rows of female line are 30 cm away from the male line, but each female line is 15 cm away from each other. The figure for transplanting pattern has been appended for your reference. In summary, the spacings would be as follows :
Among male rows 15 x 15 cm
Among female rows 15 x 15 cm
Between male and female rows 30 x 15 cm
FERTILIZERS SCHEDULE :- Avoid excessive use of nitrogenous fertilizer to check excessive vegetative growth. Following schedule is recommended (in kg/ha).
@ 36 N, 24 P2O5, 24 K2O kg/ acre)
Time of application DAP Urea MOP
(kg) (kg) (kg)
Basal at the time of transplanting 52 6 40
3 weeks after transplanting - 27 -
6 weeks after transplanting - 27 -
Apply 1/3rd nitrogen, whole of DAP and MOP at last puddling. Broadcast the remaining Nitrogen in 2 splits i.e., three weeks and six weeks after transplanting.
ROGUING :
In order to produce pure hybrid seed rouging must strictly be followed. In addition to strict isolation distance of 100 m, following additional points must be kept in mind while rouging :
TIME OF ROGUING:Early morning time is the best time for rouging. Care should be taken to complete this activity before start of anthesis so as to avoid any contamination. The rogue plants must be uprooted and destroyed. Normally the following kinds of plants are observed in the field:
MAINTAINER PLANTS : These plants have more or less similar appearance as the female plants but are 3-5 days earlier in flowering than the female line. Moreover these plants have yellow, plumpy and dehisent anthers compared to white, empty and shrivelled ones in the female.
OTHER OFF-TYPE PLANTS : Based on plant height, growth duration,spikelet number, shape and size, leaf colour and size and other morphological traits off-type plants can be identified and removed.
Note : Rouging should be undertaken from booting stage till the end of flowering.
GIBBRELIN APPLICATION AND SUPPLEMENTARY POLLINATION:
GA3 plays an important role in hybrid rice seed production. It helps in resulting better exertion of panicle from the leaf sheath thus better outpollination. GA3 spray should be done twice first at about 5-10% flowering and second one day after the first spraying Normally evening time is the best time for spraying GA3 when there are no dew drops on the crop. Effect of GA3 would be washed if it rains within 6 hours of spraying.
To prepare solution use 12 gm of GA3 for first spray and use 8 gm of GA3 for second spray per acre. Since GA3 is not soluble in water directly, dissolve 1 gm of GA3 in 5-10 ml methyl alcohol or rectified spirit and then add desired quantity of water to make the final solution. Normally 175-200 litres of water is sufficient to spray one acre crop. While spraying, care must be taken to spray uniformly .
SUPPLEMENTARY POLLINATION :
Shaking of male parent panicles by a long bamboo stick or rope pulling during anthesis (normally between 0900 hrs to 1200 hrs) period helps in spread of pollen grains widely and evenly. This helps in enhancing rate of outpollination and thus higher seed set on female panicles. It is advantagous to carry out supplementary pollination only during anthesis period. Supplementary pollination without anthesis is of no use.
Note : All sprays during crop flowering stage must be takenup only during evening hours.
HARVESTING :
MALE PARENT : Male rows should be harvested from ground level 3-4 days earlier than the female rows. After harvest, check each line thoroughly for any drop out panicles of male parent. Any negligence at this stage can cause admixtures in hybrid seed. All the harvested male rows must be stacked separately away from the threshing floor.
FEMALE PARENT: Before harvesting female rows, check thoroughly for offtypes and dropped out panicles of male parent and ensure their complete removal. Harvest the female rows and stack them near threshing floor which must be away from male stack.
THRESHING :
Ensure complete cleaning of threshing floor by thoroughly checking any drop-out seeds. Preferably use a new area for threshing female seed. Female parent should be threshed before male parent to avoid any admixtures.
Dry threshed seed in thin layers for 2-3 days. Delay in drying leads to deterioration of seed quality and germination.
Pack the dry seed in new gunny bags and label them lotwise before despatching to the company.