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.

3.  WEATHER
 NUTRITION
 SOIL MOISTURE
 PLANT PROTECTION CHEMICALS
 HORMONES
 CULTURAL PRACTICES
 MANAGEMENT PRACTICES

4.  TEMPERATURE
 DAY LENGTH
 LIGHT
 WIND
 RAINFALL

5. Most of the crops 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 low temperature (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 differences during 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 rainfall leads 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 FACTOR CHANGES 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 SEED SET
 FLOWER DROPPING
 REDUCED SEED SIZE
 REDUCED SEED YIELD

12.  Ripening of the 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 winds at or near, harvest time causes heavy seed
losses .

14.  The structural and 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 supply of 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 nitrogen deficiency 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 good supply 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 plays an 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-quality seed, 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 during flowering 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 water deficit and thermal stress during soybean
seed filling (França Neto and Krzyzanowski)

22. water deficit

23.  Herbicides and pesticides 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. AUXINS
GIBBERLINS
CYTOKININS
ABSCISIC ACID

25.  Auxins (cell elongation)
 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 of planting
Roguing
Supplementary pollination

27.  WEED CONTROL
 DISEASE AND INSECT CONTROL