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Environmental factors affecting seed development and maturation
The document discusses various climatic and environmental factors that affect seed development and quality in crops. It states that moderate temperatures are required for flowering and pollination to produce good seeds, while high temperatures can cause poor pollen development and seed set. Excessive rainfall, humidity, or winds can damage seeds and cause losses. Nutrition, soil moisture, and plant hormones also influence seed maturation and quality. Proper management practices like weed control are necessary to optimize seed production.
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Discusses key environmental factors like weather, temperature, and soil moisture essential for seed growth.
Explains how moderate and extreme temperatures during flowering affect seed set and quality.
Highlights how excessive rainfall can harm seed maturation, seed quality, and lead to diseases.
Identifies issues like poor seed set and dormancy related to temperature and humidity influences.
Outlines the role of nitrogen, phosphorus, and potassium in seed development and their application timings.
Discusses the impact of soil moisture and climate conditions on seed development and viability.
Explores the relationship between water deficit and thermal stress on seed filling.
Addresses how herbicides and pesticides influence seed quality and viability.
Describes the functions of plant hormones like auxins and gibberellins in seed growth and maturation.
Presents management strategies such as seed selection and disease control for effective seed production.
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Environmental factors affecting seed development and maturation
- 3. WEATHER NUTRITION SOIL MOISTURE PLANT PROTECTION CHEMICALS HORMONES CULTURAL PRACTICES MANAGEMENT PRACTICES
- 4. TEMPERATURE DAYLENGTH LIGHT WIND RAINFALL
- 5. Most of thecrops require moderate temperatures for flowering and pollination such that good seeds are formed. Too high temperatures cause desiccation of pollen resulting in poor seed set. If hot dry weather conditions prevail during flowering many crops such as vegetables, legumes and fruit trees fail to set seeds effectively and produce many seedless fruits .
- 6. Vegetables, legumes,fruit crops require cool conditions to flower and pollinate normally. Though oil crops can withstand hot periods during flowering, very high temperatures result in premature flowering, and production of poor quality seeds. Very cold temperatures may also damage seed quality especially in the early phases of seed maturation
- 7. Very lowtemperature (0⁰C and below)damages ripening of corn seed. (Rossman, 1949). Very high temperature increases the rate of respiration, decreases grain weight. In Lettuce koller (1962) noted that when the seeds matured at high temperatures, germination was less at 26⁰C in the dark than the corresponding low temperature matured seed.
- 8. Temperature differencesduring ripening also altered the dormancy patterns of wheat (Van Dobben, 1947; Kramer, Pest, Witten, 1952). In Mungbean, Dharmalingam (1982) showed the late summer sowing in Tamil Nadu resulted in the production of high % of hard seeds.
- 9. Excessive rainfallleads to higher incidence of pests and diseases and makes seed useless. It may result in delayed maturity and pre germination of seeds in many standing crops. Heavy rainfall at harvest time may cause heavy seed losses .
- 10. CROP CLIMATIC FACTORCHANGES IN SEED CHARACTER Sorghum Rainfall or high humidity at maturation Blackening of seed due to black mould Pulses Rainfall at maturation Off coloured seed Peas High humidity at maturity Mottled seed Groundnut Rainfall at harvest Insitu germination Brinjal High temperature at flowering Pseudo styled flowers Tomato Rainfall at harvest Insitu germination Bhendi Rainfall at maturity Off coloured seed
- 11. POOR SEEDSET FLOWER DROPPING REDUCED SEED SIZE REDUCED SEED YIELD
- 12. Ripening ofthe seed on the Parent plant. Chinapodium amaranticolor and ononis sicula seeds maturing during long days showed coat-imposed dormancy due to thickening of the seed coat ( Lona, 1947, Austin, 1972). Ample Daylength is required for better seed development and maturation.
- 13. Strong windsat or near, harvest time causes heavy seed losses .
- 14. The structuraland textural status of the soil, its fertility level, pH, microbial environment. In the nutrition of seed crops, nitrogen, phosphorus, potassium and several other elements play an important role for proper development of seed. It is advisable to know and identify the nutritional requirements of seed crops and apply adequate fertilizers. Adequate fertilization results in good seed development and maturation.
- 15. Adequate supplyof nitrogen is very important for a good healthy seed development. Excess quantity of nitrogen prolong the growing period and delays the seed maturity. Time of application of nitrogen is important. The second application often leads to an increase in quality seed. In some crops dressings at flowering tends to delay in seed ripening.
- 16. Severe nitrogendeficiency in carrot, lettuce, and pepper resulted in poor seed development. High dose of nitrogen reduces development in seed due to accumulation of germination inhibitors
- 17. A goodsupply of phosphorus helps in good seed development. Phosphorus deficiency retards overall growth and development. It should be applied in the soil before sowing In certain crops, a side dressing of phosphorus is also applied at the time of flowering. The P reserves in the seed in the form of phytic acid and acts as a antioxidant. Deficiency of P causes watercress seeds.
- 18. Potassium playsan important role in flowering and seed development. Helps in synthesis of proteins and fat in oil crops. Severe deficiency of potassium in pepper resulted in a higher percentage of abnormal seed production. Deficiencies of other essential major and minor elements may also affect the quality of seeds.
- 19. For good-qualityseed, a relatively dry climate during the ripening phase is preferred. Even for a wetland crop like rice, a dry climate during grain ripening phase produces seeds of good quality Adequate soil moisture is essential for good seed development. Soil with high moisture due to high irrigation or high rainfall may lead to seeds of low nitrogen and protein content in case of wheat.
- 20. Drought duringflowering might interfere with fertilization, thus seed number is reduced. Weight and size of seed which are usually correlated with viability, are reduced by drought during seed development and maturation. Extreme water deficit stimulates premature desiccation, and affect the quality of seed. As such seeds badly affected by pre-harvest rains should not be stored for planting purposes.
- 21. Association of waterdeficit and thermal stress during soybean seed filling (França Neto and Krzyzanowski)
- 22.
- 23. Herbicides andpesticides applied to the soil or to the growing crop may affect the development of seed and influence its quality. If the concerned herbicide or pesticide is not easily biodegradable. Increase in the protein content of wheat with sub herbicidal doses of Simazine (Ries, Schweizer, and Chmiel, 1968). Ramamoorthy (1990) systemically studied the effect of the herbicides FLuchloralin, Pendimethalin, on viability of seeds.
- 24.
- 25. Auxins (cellelongation) Gibberellins (cell elongation + cell division - translated into growth) Cytokinins (cell division + inhibits senescence) Abscisic acid (abscission of leaves and fruits + dormancy induction of buds and seeds) Ethylene (promotes senescence, epinasty, and fruit ripening)
- 26. Seeds selection Isolation Time ofplanting Roguing Supplementary pollination
- 27. WEED CONTROL DISEASE AND INSECT CONTROL