Seed production in wheat hybrid seed and others

Seed production in wheat hybrid seed and others

1. Seed production in wheat Dr. Sheeja K Raj Assistant Professor (Agronomy)

2. Wheat is the staple food for over ten billion people in as many as 43 countries of the world. Wheat provides nourishment to 35% of world population. Wheat cultivation has traditionally been dominated by the northern region of India. The northern states of Punjab and Haryana Plains in India are the major wheat producers. The other major wheat production states are Uttar Pradesh, Punjab, Haryana, Madhya Pradesh, Rajasthan, Bihar, Maharashtra, Gujarat, Karnataka, West Bengal, Uttaranchal, Himachal Pradesh and Jammu & Kashmir.

3. Wheat in India Second most important winter cereal after rice. Bread wheat contributes approximately 95% to total production Remaining 4% from durum wheat and 1% from Dicoccum 11/12/2010 3

4. Seed production in wheat Family : poaceae Chromosome number: Diploid : 2n =14, Tetraploid : 2n = 28, Hexaploid : 2n = 42 Floral biology of wheat : The inflorescence of wheat is called spike consisting of spikelets (15-20 no.) Spikelets are borne on zig zag rachis in two alternate rows with a terminal spikelet. The spikelets are sessile and each spikelet contains 3-7 florets. Only lateral florets are fertile and the central ones may be sterile. At the base of each spikelet, there are two oppositely placed empty glumes. Each floret comprises of a lemma ending in awn, a palea , 2 lodicules, androecium & gynoecium. The androecium consists of 3 stamens with thin filament & large bilobed anthers. Gynoecium consists of monocarpellary superior ovary with two feathery stigma.

5. Main Culm flowers first & the tillers bloom later in order of their formation . Flowering starts at approximately 2/3 from the base and proceeds in both the directions. Blooming remains throughout the day & it takes 3-5 days for completion . Flower opening is usually during warmer part of the day i.e. , between 9 am to 2 pm and peak period between 10 am to 1 pm Anther dehiscence takes place simultaneously & hence the crop is highly self- pollinated ( < 1% cross pollination)

6. Seed development Stages in Wheat Kernels at various stages during grain filling: a) kernel at watery ripe b) kernel at late milk c) kernel at soft dough d) kernel at hard dough showing loss of green color e) kernel ripe for harvest Physiological maturity: When the kernels have attained maximum dry weight it is physically matured. Note the green color is gone from the peduncle and head parts . 11/12/2010 6

7. Wheat seed multiplication : To maintain the purity, a generation system of seed production is followed. In India four to five generation are commonly adopted. Breeder seed- Foundation seed I – Foundation seed II- Certified seed I- Certified seed II Breeder seed- Foundation seed I-Foundation seed II- Certified seed

8. Climate: Optimum temperature for germination is 20-22 C, vegetative growth 16-22 C and during grain development wheat requires a mean maximum temperature of about 25 C for at least 4-5 weeks. Land requirement : The land selected should not be cultivated with the same crop in the previous season, should be free of volunteer plants and weeds, well drained, fertile with good irrigation and drainage facility and with neutral pH.

9. Isolation distance : Normally a self-pollinated crop (Cleistogamous). 1-4 % Cross pollination sometime occurs. Wheat seed field should be isolated from all sources of contamination (genetic, physical and pathological).

10. Field standards Contaminants Minimum distance (m) Foundation Certified Isolation distance     Field of other varieties 3 m 3 m Field of same variety not conforming varietal purity 3 m 3 m Field of wheat, rye, triticale with infection of loose smut disease in excess of 0.1 % and 0.5 % 150 m 50 m Specific requirements Maximum permitted (%) Off types) 0.05 0.20 Inseparable other plants 0.01 0.20 Plant affected by seed borne (loose smut disease) 0.1 0.50

11. Popular varieties : North western plain zone : Irrigated normal sown: PBW 621, PBW 550, WHD 943 (d), WH 1021, WH 896 (d), HD 8521, HD2687 etc. Irrigated late sown: UP 2338, UP242, PBW 509, Raj 3777 etc. Rainfed: PBW 396, PBW 527, C306, WH1080 etc. North Eastern Plain zone Irrigated normal sown: DBW 39, CBW 38, HD2733, HD 2402, HD2733, Raj 4120 etc. Irrigated late sown: HP 1633, HP 1209, HUW 234, HP 1744, DBW 14, K9533 etc. Rainfed: K 9341, K307, HD2888, MACS 6145 etc.

12. Central zone Irrigated normal zone: DL803-3, MPO 1106, GW 366, GW322, HD 2236, GW 273 etc. Irrigated late sown: MP3288, MP1203, HD 2932, GW 322, Swati etc. Rainfed: MP 3020, C 306, Sujata, HI 1531, HI 1500, JSW 17 etc. Peninsular Zone Irrigated normal zone: MACS 6222, Raj 4037, Ra 4083, HUW 510, DWR 1006 (d) etc. Irrigated late sown: HD 2501, HD 2932, HD 2833, PBW 533, HUW 510, DWR 195 etc. Rainfed: Bijaga yellow, MACS 2846, HD 2781, K9644, PBW 596 etc.

13. Seed selection & seed treatment Seed Selection : Seeds used for seed production should be of good quality certified seeds from an authentic source. Seeds should be healthy, uniform in size and free from the insect or disease attack and with good germination percentage. Seed treatment: Selected seeds should be treated in order to improve the germination potential, vigour and resistance to pest and diseases. Seeds can be treated with Trichoderma viride @ 8 g/kg of seed and dried in shade. Seeds can be treated with a mixture of biofertilizers Azotobacter and PSB, biofertilizer like Bacillus / Aspergillus @ 20 g/ kg of seed. Shade dry the seeds and sow within 6 - 8 hours of treatment. Seed can also be treated with Vitavax 75 WP or Bavistin @ 2.5 g/kg of seed to prevent from seed borne diseases

14. Time of sowing Zones Optimum sowing time Northwestern plains Second fortnight of November for short duration varieties First fortnight of November for long duration varieties Northeastern plains and central zones Second weak of November for short duration varieties First weak of November for long duration varieties Peninsular zone October second fortnight for all the varieties

15. Method of sowing: The seed crop is sown in rows with a seed drill, or sow behind the plough in furrows. Seed drill should be thoroughly cleaned and checked before use. Depth of sowing: Seed should be placed 5-6 cm below the soil surface where sufficient soil moisture is available to enable germination. Deep sowing delays the emergence, resulting in weak seedlings and poor yield. Seed rate: The recommended seed rate for seed crop is 80 kg/ha for timely sown crop and for late sown crop-100 kg/ha. The seed should be treated with systemic fungicide to control loose smut. S pacing: The row distance for seed crop should be kept at 22 to 23 cm to facilitate rouging and inspection work. For late sown row spacing should be15-18 cm.

16. Fertilizer Recommendation : NPK recommendation: 80-120: 50-60: 40 kg NPK per ha. Full P and K and half N should be applied at the time of sowing, or just before sowing and remaining half N at the time of first irrigation. In rainfed conditions, entire dose of fertilizer should be applied at the time of sowing. 15 to 20 kg/ha zinc may be given at the time of sowing in case of deficiency. Irrigation : Depending on the soil, four to six irrigations may be given. The first irrigation should be given at crown root initiation stage, about 30-35 days after sowing. Other irrigations should be given at late tillering, late jointing, flowering, milk and dough stages. Two to three extra irrigations may be given on light soils. Crown root initiation and heading stages are the most critical to moisture stress.

17. Weeding : Important broad-leaved weeds infesting wheat are Chenopodium album Chenopodium murale Fumaria sp. Melilotus alba Anagalis arvensis Cirsium arvense Carthamus oxycantha Asphodelus tenuifolius

18. Important grassy weeds infesting wheat are Phalaris minor Avena fatua Lolium temulentum Lolium rigidum Polygonum monosepeliensis Poa annua

19. Weeding is important during early stages of cultivation. Critical period for crop weed competition is first 30-45 DAS. Weeds can be controlled by periodic hoeing and manual weeding. For rainfed crop two manual weeding is enough. For irrigated crop, a minimum of three weeding during 20-25, 40-45 and 60-65 days after sowing. For control of broad-leaved weeds spray 2-4 D @ 0.5kg/ha in 750 liters of water or Metsulfuron methyl 4 g/ha or Carfentrazone ethyl 20 g/ha applied at 25 to 30 DAS. For the control of grassy weeds pre-emergence application of Pendimethalin (stomp) @ 1 kg/ha in 750 liters of water or post emergence application of Isoproturon @ 1 kg/ha or metribuzin 200 g/ha or sulfosulfuron 25 g/ha or Fenoxaprop-p-ethyl @ 100 g/ha in 750 liters of water at 30 DAS.

20. Field Inspection: The first inspection should be carried out after ear-emergence when seed has started to fill. Latter inspection at the maturity stage. During inspection parameters such as isolation requirement, off types volunteer plants, diseased plants etc., are to be checked.

21. Rouging: Rouging should be done from vegetative phase to harvesting phase. The seed production field should be checked for off-types and diseased plants and rouged off. Major rouging is done before flowering stage to assure the genetic purity of the seeds. Off-types are identified by plant type, plant height, days for flowering, leaf colour , panicle shape and colour of glumes etc. Maximum percentage of off-types permitted at the final inspection is 0.050% for foundation seed production and 0.20% for certified seed production.

22. Diseases   Flag smut, loose smut Seed treatment with carboxin @2.5 g/kg seed or carbendazim 2.5 g/kg seed or Tebuconazole 1.00 g/kg seed two days before sowing Kernal bunt Use healthy seeds, seed treatment with thiram @ 2.5 g/kg seed, spraying of propiconazole 0.1 % at ear head emergence stage Rust disease As soon as yellow rust is observed in the field spray Propiconazole or Tebuconazole @ 0.1 % Pests   Termite Seed treatment with chlorpyriphos (500 ml of chlorpyriphos in 5 litres of water for 1 quintal of wheat seed) Army worm Spray methyl parathion/ Spinosad Aphids Imidacloprid 20 g/ha Seed gall nematode Use clean seed

23. Harvesting : Harvesting is done soon after the maturation of the seeds turn green to straw yellow in colour . Ear heads should be harvested when the seeds attain maximum physiological maturity. Irrigation to the seed plot should be withheld at this point to facilitate the drying of the crop/ seeds. Crop should be harvested with their panicles intact.

24. Threshing and Processing : Harvested plants should be stacked on a clean floor of the threshing yard free from other varieties. Harvested plants with a moisture content of 15% should be threshed by hand beating or threshers. This level of moisture content is safe for threshing without any mechanical injury to the seeds. Threshed grains are winnowed and cleaned. Cleaned seeds are dried to attain a safe moisture content of 12 – 13 % and graded using a suitable sieve to remove chaffy, under and oversized seeds.

25. Drying and storage The cleaned and graded seeds are dried to attain 12 - 13% of moisture content. Normally the seeds can be stored for one year under ambient storage conditions without losing much of the germination potential

26. Seed standards Factor Foundation seed Certified seed Pure seed minimum 98 % 98 % Inert matter maximum 2 % 2 % Other crop seed maximum 10/kg 20/kg Total weed seed maximum 10/kg 20/kg Objectionable weed maximum 2/kg 5/kg Seed infected with kernel bunt (maximum) 0.05% by number 0.25 % by number Germination (minimum) 85 % 85 % Moisture (maximum) 12 % 12 % For vapour proof container 8 % 8 %