Sowing healthy seeds or seedlings leads to the healthy and better harvests. Present agriculture technologies enforces to produce sturdy and healthy seedlings
Some of the seeds of vegetable crops like tomato, brinjal, capsicum and cucurbits are first raised in nursery under protected conditions to achieve maximum germination count and healthy plant establishment and then transplanted to main field.
Farmers and nursery managers are raising seedlings in plug trays or portrays to produce the healthy seedlings. Soil less media with coco-peat, vermiculite and microbial consortium is usually used to sow the seeds and the rooting media. Sowing is done manually and also with seed sowing machine.
Importance of vegetable seedlings production in protected nursery
- Less loss of expensive seeds
- Proper seed germination, uniform growth, least seedling mortality
- Least pest and disease incidence
Components and process involved in modern nursery raising system
Seeds, Seedling tray, media, mechanization, irrigation, nutrients, protected structure, light and seed pelleting and priming, biological enhancement and hardening.
Different sized trays with varied numbers of cells are used to grow the seedlings in vegetable nurseries. The number of cells in portray varies from 72 to 800 cells per standard tray (53.7 X 27.5 cm). Size of the cell is important as it controls the amount of media used as well as water holding capacity. Seedlings produced in larger cells are taller and have greater dry weight than those grown in small cells
The chemical and physical properties of the growing media is a key factor for successful nursery production.Optimum root growth is largely dependent on physical characteristics of media like water, aeration and nutrient holding capacity of the media.
Sterile growing media must be used and may or may not be inert, but it should have proper cation exchange capacity (CEC) which is associated with pH and nutrient absorbing capacity. Coco peat which is a byproduct of extraction of fiber from coconut husk a 100 % natural, biodegradable, fibrous and spongiest material is normally used as main ingredient of nursery growing media. It has high C: N ratio, high water holding capacity about seven to nine times of its own weight.
Coco peat has antifungal and antibacterial properties. For additional benefits to growing seedlings biological agents like biofertilisers and Trichoderma viride and Pseudomonas fluorescens are usually mixed to media. Normally approximate 1.2 kg of cocopeat is required for filling one portray.
Better germination of seeds depend upon the temperature and usually should be warm with uniform moisture in the media. Customized germination chambers are designed to use in nurseries for better germination. Black polyethylene sheet is used to cover the portrays after sowing to facilitate warmer temperature to initiate germination.
Ideal temperature in root zone required for some of the vegetable seeds to germinate
Tomato and Brinjal 210 C – 240 C ; Chilli and capsicum 28 0 C to 320 C
The ideal root zone temperature is 26 0C to 290 C during the first four weeks of growth of seedlings and 20 0C to 26 0C during the fifth and sixth weeks.
Seedlings should be irrigated regularly for better growth and development of the seedlings. Nursery growers use rose can or flush boom to irrigate the seedlings. Over watering also is dangerous for the growing seedlings as there might be chances of developing foliar diseases, collar and root diseases.
Nutrition for growing young seedlings is very much necessary apart from the nutrients present in the cocopeat or growing media. The nutrition is supplied through foliar application for the growing seedlings.
For better root growth phosphorous is required with little nitrogen sso 12:61:00 root drenching may be applied once at 12th day after germination. Once micronutrient mixture may be sprayed 15 days before transplanting. Deficiency of any nutrients may lead to poor and stunted growth of plants and resulting in poor performance.
Young growing seedlings requires extra protection at the younger stage as they are soft and tender so that the sucking pests are very much attractive to suck the juice and at the same time they act as vectors to spread many contagious and deadly diseases those may occur later in plant development stages.
These kind of chances are more when the seedlings are raised outside the protected structure or open field.Protective structure also protect the young seedlings from adverse climatic conditions like rain, wind, heat and many diseases.
In protected structures, poly house kind of structures are constructed with transparent UV stabilized polyethylene film 200 micron thickness as covering the poly house roof. A retractable or movable shade nets, at about 11 feet height are provided for regulating heat and light in the ploy house.
The sides of the poly house structure is usually covered with 200 micron thick polyethylene film to a height of 3 feet from the ground level, to have better protection from rain splash. From 3 feet height the side wall is covered with 40 micron white colored insect proof net from all the four sides.
Shade net nurseries
A shade net nursery is usually erected using GI pipes or stone slabs as a support. HDPE green or black colour UV stabilized shade net of 50 to 75% shade intensity is used to cover the nursery area at a height of 6.5 feet. Strong stainless wire grid is provided at the top of the structure as support for shade net.
UV stabilized 40 % nylon insect proof net mesh is fitted on all the four sides of the nursery to prevent insect entry. Polythene sheet is to be provided to pull over the pro-trays in the event of rainfall by way of making low tunnel structure.
The structures should be provided with an ante chamber with two doors constructed at opposite directions where entry or exit to the poly house is made through the first door and then after closing the first door, the second door is opened to make an entry into the poly house.
Both the doors are not opened at single time or simultaneously so that pest entry into the protected structures is not given a chance to enter and attack the young seedlings. A small concrete trough of 2 meter length, 1 meter breadth and 2 inch depth should be prepared between the two doors of antechamber for facilitating washing legs in the disinfectant solution (Potassium permanganate) to prevent any contamination inside the nursery structure.
Light requirements for seedling growth and development is very important and very crucial. Structure need to be constructed in such a ways that sufficient light is ensured for seedling production.
Hardening is the process of gradually exposing grown up seedlings to the normal climatic condition from protected condition to reduce stress and reduce transplanting shock when seedlings are transplanted to the main field.
Hardening may be done by increasing light intensity slowly or exposing transplants under full sunlight, reducing irrigation or watering and fertilizer application.
Pest and disease management.
- Cleanliness and hygiene in the nursery, among the crate or portrays is most important role in the control of pests and diseases.
- Regular sterilization of the growing media, structures, tools and trays must be done with use of steam or chemical.
- Disease prevention may be effective with proper and effective ventilation and air movement within the nursery area.
- Pests and diseases that could affect the growth of healthy seedlings to be understood and effective measures need to be planned well in advance.
- Pesticides application should be carried out with extra care and be aware that greenhouse/ Nursery raised plants may be more sensitive to chemicals than in the open field.
K SANJEEVA REDDY,
Senior Agronomist, BigHaat.
For more information kindly call on 8050797979 or give missed call on 180030002434 during office hours 10 AM to 5 PM
Disclaimer: The performance of the product (s) is subject to usage as per manufacturer guidelines. Read enclosed leaflet of the product(s) carefully before use. The use of this product(s)/ information is at the discretion of user.
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