And it is only to be expected that seeds harvested in different pre-harvest condition which will have caused different amounts of deterioration by the time seeds are harvested. It is suprising then that samples of seed obtained from different sources may show differences in viability behaviour. Further, if seeds are kept at higher moisture contents than mentioned in table the losses could be very rapid due to mold growth on and in the seed (12 to 14 per cent moisture content), or due to heating (18 to 20 per cent moisture content). Biotic factors. Factors Affecting Longevity in Storage Seed condition. It is not always easy to know and satisfactorily assess what the causes of these differences are, or even sometimes to know how important they are, because of wide variability between samples from different sources. Adequate storage precautions at all these points, therefore, are also necessary. For cereals in ordinary storage conditions for twelve to eighteen months, seed drying up to ten per cent moisture content appears quite satisfactory. Factors Affecting Seed Longevity in Storage. Special Effect of Extreme Storage Conditions on Viability: Researches indicate that three sets of extreme storage conditions of temperature and moisture contents, say about 30 percent, in cereals provided the temperature is suitable, germination will result in loss of viability when seeds are very moist, thirdly , if seeds are subjected to extreme desiccation , the period of viability may be less than expected. Contact insecticides – used in seed storage include DDT, lindane and Malathion. Fully ripened seeds retain viability longer than seeds collected when immature (Stein et al. Both are influenced by harvest and storage practices. Temperature, nutrients and other environmental factors also affect seed development and influence seed quality. Testa quality and physiological age are two principle components of pea, lentil, faba bean and chickpea seed quality. Rodents and Birds. The five most important factors affecting seed longevity are 1. Seed quality 3. Low temperatures are very effective in maintaining seed quality, even through relative humidity might be quite high. These includes seed moisture content, temperature, relative humidity, initial viability, stage of maturity at harvest, storage gas and initial moisture content of seed entering into storage14. Even in ideal storage conditions seed will soon lose viability if it is defective from the start. The safe moisture content, however, depends upon storage length, type of storage structure, kind/verity of seed, type of packaging material used. The higher moisture content of the seeds, the more they are adversely affected by both upper and lower ranges of temperature. Seeds attain specific and characteristic moisture content when subjected to given levels of atmospheric humidity. Seed type 2. ��;[y0%Ec���9��$��j�]�����.t�}t�8��_�8�CMI��>N9���o�6�ظ�QtlTK���,�h��hU1l�m�cK�2Y�h��g3elR|��[�Y����=|(�������_��|O�SNf��V��56׼1�(�������GΑF�����z���G'�h��|!���1�@�6��XI�G|Ќt�}��P��} 1}�tOQ@�蜀� F�����V�>ŋ^}�~������x�e�?3�%'�7e�� oMϥw��.��H J�M�#�K�m����+�>��l���- ns�+�u����w�Y��w�`I���z� �j@��g�2p���1�x\�� The important implication of this is that only high quality seed should be carried over. Maintain Cool Conditions Keep seeds out of direct sunlight in a cool spot that maintains a fairly consistent temperature. A period of time is required, the length of which varies with the seed kind, initial moisture content, the average relative humidity and the temperature. <>/XObject<>/ExtGState<>/Pattern<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/Annots[ 14 0 R] /MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> More critical investigations are needed on the effect of fluctuating environmental conditions. The seed quality and viability during storage depend upon the initial quality of seed and the manner in which it is stored. [��6%|� ��D�L8���v,�Bp?{�������9��4�?�˹��%����Dr��? The activity of all these organism can lead to damage resulting in loss of vigour or viability or, particularly in the case of rodents, to complete loss of seed. '��z?�0g�w��S���������Hav�=_�xo�A`tA��!�Br�z�ַ{c]����2�A��HBi�)��ϨR�EQ�1FqJ/��Ĩ�OLX%��Ir���l~ Z�9��@�5��(�8�M�V���]��A{���Q���6��L G��kؼρ�*�ۀ��&j��FۜT�"}��a�. Seed placed in an environment with a relative humidity higher or lower than that with which its moisture content is in equilibrium , will gain or lose moisture until an equilibrium is established with the new environment . Rodent , control measures include building the store so that the floor is 90 cm above ground level at the entrances ; having a 15 cm lip around the building at the 90 cm level of the floor; and providing a removable deck at the entrance for use only when seed is being loaded or unloaded. Establishment of moisture equilibrium in seeds is a time dependent process. According to Utah State University grains containing less than 12% moisture and pulses (legumes harvested solely for the dry seed) with less than 10% moisture can … (��}/�~��H?�g }C�βo�d�����(�{(�n��n�@�MO3���I�P��P�dkx�\: ��`|y¬��: Lv|���PK�zb���m Rats and other rodents are more serious problems. Relative Humidity and Temperature During Storage: Relative humidity and temperature by far are the most important factors determining the storage life of seeds. This characteristics moisture content is referred to as equilibrium moisture content, for a particular kind of speed at a given relative humidity, tends to increase as temperature decreases and as deterioration progresses. 3. Quality of the seeds Quality of the seeds can be greatly influenced by various environmental conditions from the stage of physiological maturity to harvest. 4 0 obj Absorbed Moisture Content of Cereals Seeds in Equilibrium with air ( Harrington, 1959): Approximate Moisture Content of Vegetable Seeds in Equilibrium with Air. Deterioration in seed quality may begin at any point in the plant’s development stage from fertilization onward. Depending upon the severity of damage, or degree of deterioration, E. g extent of weathering damage, mechanical injury, flat, wrinkled or otherwise damaged seed, even seed lots of good germination, at the beginning of storage, can and do decline rapidly within a few months. Temperature is an important factor for the safe storage of foodgrains and other food materials as it affects the growth of insects … 1 0 obj However, for storage in sealed containers, drying up to 5 to 8 per cent moisture content, depending upon the particular kind, may be necessary. some similar kinds, E. g Tall fescue and annual rye grass, though they look very much alike, differ considerably in storability, similarly, the genetic make-up of the lines/ varieties in the same kind also influences storability. The amount of moisture in the seeds is probably the most important factor influencing seed viability during storage, over most of the moisture range, the rate of deterioration increases as the moisture content on seed storability. Since the life of seed and its span largely revolves around its moisture content, it is necessary to dry seeds to safe moisture contents. Provenance:  It has already been stated that a number of factors, operating before and during harvest can affect seed viability. The seed storability is considerably influenced by the kind / variety of seeds.


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