Quality Seed Production of Okra
Okra (Abelmoschus esculentus(L.) Moench) is an important vegetable crop of the tropic and sub- tropic It is grown during summer and rainy season and hence classified as warm season crop. Okra is cultivated for its immature edible fruits known as pods; the mature fruits are also dried and stored in parts of Africa for local use in high temperature season. The average productivity of okra in India is 9.8 t/ha (NHB-2001), which is less than the productivity (15t/ha) realized through the trails. The low productivity in okra is attributed poor see replacement due to the limited availability of quality seed and high incidence of pests (jassids, white fly and borers) and yellow vein mosaic virus (yvmv) which severely affect the crop during the khairf in the north. Since, the hybrid seed is marketed by the private sector companies in sizable amount and cover the smaller area. Thus, the larger area is sown through the op varieties seed across the country. Therefore, to boost the productivity there is a need to strengthen the production of quality seed. This could be made possible by organizing the seed production of the op varieties the in a compact area/seed village concept which can help an improving the seed replacement rate (SRR).
Land requirement: Select fields on which the okra crop was not grown in the previous seasons, unless the crop in the previous season was of the same variety. The soil should be fertile, and field should be leveled, well drained, free from perennial weeds viz. motha (Cyprus rotandus) and santh (Trinthema) and soil borne fungus (Fusarium wilt). The pH of the soil should be between6to6.8
Where to get the seed? The seeds of high yielding varieties and of various classes are available with ICAR institutes (IARI and IIHR)/SAU(PAU and CCS HAU)/.NSC/SFCI for further multiplication can be purchased from them by advance indenting.
Isolation and pollination; The seed production plot must be isolated from the field of the other varieties and from the same variety not confirming the varietial purity and wild species at least 200m for quality seed. The flowers of the okra are cross-pollinated by insects (butterfly) although self-fertilization may also occur.
Time& method of sowing: In north India, okra can be sown from February to July and in south through out the year. The seed crop is best timed so that pod repining does not coincide with the rain or repining should occurred under relatively in dry conditions. The best time for sowing in north India is 15th June to25th June for kharif and last week of February for summer. However, summer seed crop gave less yield than the kharif being short growing period but scape from the virus. The delayed sown seed crop result lower seed yield and poor seed quality (Table-1). The seed crop should be sown in rows on the flat beds at 2-3 cm depth. The seed can be sown behind the plough or drill but depth of the sowing should be monitored.
Manure and fertilizer: 10-15 card load of well-rotted FYM should be incorporated in the selected field 30-45 days before the final preparation of the plot. The Chemical fertilizer NPK should be applied in 1:2:1 ratio at the time of sowing/final field ploughing. However, 40-60kg nitrogen/ha should be applied in 30-45 days old crop through top dressing to boost the growth.
Seed rate and spacing: During kharif; sowing rate of 8kg/ha and12-14kg/ha for summer crop is ideal. The plants are thinned to 30-45cm apart in row according to the season and vigour of the variety. However, row spacing of 60cm and 45cm is suggested for rainy and summer season respectively. It is also suggested that after10-15 of rows a gap of two rows should be left to facilitate the rouging and inspections.
Flowering and rouging stages: The most of the okra varieties are short day in nature and does well at 30-40 C temperature but exceptions are also there. It is believed that seed crop thrive well in areas with a relatively lower day and night differential.
Rouging should be begin with uprooting and destroying of the YVMV affected plants soon they are noticed and this should continued up to three fruit stage. Before flowering; the plant height, growth habit, pigmentation over the leaf, stem petioles etc. should be checked. At flowering; the flower size colour intensity and pigmentation over the base of the petals should be examined and the plants showing the variation should be uprooted. At fruiting; fruit shape, colour , and nos .of the ridge should be checked and the plant affected with YVMV must be removed and buried.
Major pests, diseases and their control: Among the pests; borers, jassids, white fly, red spider mite and pollen eating beetle are the major ones, which could be controlled through the efficient use of modern age chemicals and integrated pest management approach. The fusarium wilt, yvmv, powdery mildew and leaf enation blight are the chief diseases of the okra seed crop. The wilt attacked on germinating seed and seedling at early crop growth stage. The yvmv can attack at any stage of the crop and transmitted by the white fly, hence the check on white fly is necssary. However, the leaf enation blight appears late crop growth stage and lead to the complete defoliation. Adopting the crop rotation, solarisation of the plot in May and June, seed treatment and spraying of the suitable fungicidal spray of the diathane M-45 or ridomil these diseases can avoid/ controlled.
Harvesting and threshing: The maturity of pods in okra occurs in a sequential order on the plant, therefore the repeated harvesting of the pod is recommended. The angular fruited varieties of okra have a tendency of shattering and delayed harvesting lead to the lose of seed yield. At maturity the pods turn grey to brown and that is the ideal stage of the harvesting of the pods otherwise pod may split. The pods are harvested manually and it should be done preferably in forenoon before 11 am. Seeds are extracted from hand-harvested pods when they are dry and brittle. The most efficient method of seed extraction by hand twist the pods open, or the pod are flailed by hand or with thresher.
What to be cared? : It is recommended that an initial 1-3 pods depends upon the variety should be harvested for fresh pods for fresh market to encourage the growth and flower development. The last few pods/ terminal pods borne in clustered should also be avoided being seed is poorly developed in them (Table-2). The pods damaged by the insects may be avoided at the time of harvesting and threshing, otherwise, the discolored seed will pose the problem & reduced the physical quality of the lot and it is very difficult to remove these discolored seed mechanically form the lot. Before threshing the pods the pods should be dried thoroughly to enhance the machine efficiency and seed recovery otherwise, good amount of seeds will remained in the base of the pods.
Seed yield and 1000-seed weight: The seed yield is greatly influenced by the variety, season, location and management practices Under normal conditions the seed yield of 10-12 q / ha can be obtained. However, in certain pockets of Gujarat and AP the higher seed yield of 18-20q/ha have been achieved.
The 1000-seed weight of okra seed varies from50-67gm.
Table-1:Effect of sowing time on growth characters, seed attributes and seed quality in cv. A-4
||Days to first flowering
||No. of pod/plant
||No. of seed /pod
||Seed vigor index
Table-2-Effect of pod position on seed yield and quality in okra cv. A-4
||No. of seed /pod
||Seed yield/pod (g)