Maize hybrid Seed production techniques

Land Requirement

• Land should be free from volunteer plants. The previous crop should not be other varieties of the same crop. It can be the same variety if it is certified as per the procedures of certification agency.

Field Standards

A. General Requirements

Isolation

• Space isolation: Maintain a distance of at least 400 meters between the seed crop and any other maize field that has a different variety planted.
• Time isolation: Sow the seed crop a month earlier or later than neighboring maize fields.

Seeds and sowing
Seed rate

• Female parental line: 15 kg/ha;
• Male parental line: 10 kg/ha
• Female and male block ratio : 8:2

Pre-sowing seed management

• Soak the seeds in 2% KH2PO4 in the seed to solution ratio of 1:1 for 8 h.
• Coat the seeds with TNAU Vidhai Amirtham @ 11 ml / kg of seeds.

           
        Uncoated seed                    Coated seed                       TNAU Vidhai Amirtham

Season

• June - July and November - December.

Spacing

• 60 x 25 cm.

Planting ratio

• Sow the female and male parents in the ratio of 4:1 or 4:2..

Border rows

• Sow four rows of male parent all around the field for effective pollination and prevention of contamination by foreign pollen. .

Fertilizer requirement

• The crop requires NPK @ 250:75:75 kg/ha. Apply NPK kg/ha.
• Apply quarter of the dose of N; full dose of P2O and K2O basally before sowing.
• Place half of the dose of N on the 25th day of sowing and remaining quarter of N on the 45th day of sowing.

Rogueing

• Based on the distinct and diagnostic characters of inbred lines given during release of hybrids, remove off-type plants, diseased, late and weak plants. Rogue off-type plants that deviate from the given inbred with respect to root and stalk development, plant type, pigmentation, leaf and stem pubescence, tassel and ear traits, and seed colour..

Detasselling

• Detasselling is the removal of tassel from female parent. Detasselling is done when the tassels emerged out of the boot leaf, but before the anthers have shed pollen. Anthers take 2-4 days to dehisce after complete emergence. Only in few cases, the anthers start to dehisce before its complete emergence. In such cases, detasselling should be done earlier. Detasselling is done every day from the emergence of tassel and continued for next 14 days..

Precautions to be adopted during detasselling

• No part should be left on the plant as it may cause genetic contamination.
• Do not break the top leaves as it may reduce the earning of source material required to accumulate in sink [seed].
• Detasselling should be done only after the entire tassel has emerged but before anther dehiscence and immature.
• Mark the male rows with marker to avoid errors in detasselling process.
• Look out for shedders [shedding tassel] in female rows as they may also cause contamination.
• After pulling out the tassel, drop it there itself and bury in soil. Otherwise late emerging pollen from detasselled tassel may cause genetic contamination.
• Do not carry the tassel through the field as shedding pollen may lead to genetic contamination.