Principles Establish a uniform plant stand, Transplanting gives a better stand than direct seeding. Wet direct seeding can be problematic. Direct seeding requirements Need more uniform land levelling and better water management Seed planted too deep results in poor emergence and weak plants Seed planted too shallow is susceptible to bird and rat attack Soil strength - For wet direct seeding, if a stick is dragged through the mud and the soil holds a shape, then the seed will not sink too deep. If the shape freely collapses, then the seed will likely sink too deep and have problems emerging. Lodging can be reduced by Transplanting (especially in the wet season), Choice of variety, Limiting N applications between Panicle Initiation and flowering, and Reducing stem based diseases.

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Dry direct seeded Use Clean Seed -contributes to yield increase by 5-20% Weed pressure tends to be more in dry direct seeded systems. Dry direct seeding can use more water and fertilizer if there is no natural hardpan to limit infiltration and percolation Seeding depth Target planting depth - <1 cm, if drilled - 0.5 cm (maximum 1cm - Variety dependent) Surface seeding can have problems of birds and rats - broadcast and harrow if possible Seed rate - 80 to 120 kg seed/ha Options Broadcast/ Broad cast in furrow Seed rate - 80 to 100 kg/ha Prepare land with furrows 15 cm apart and 5-10 cm deep - broadcast and harrow lightly - seeds will emerge fairly strongly in rows Drill seed in rows Seed rate - 80-90 kg/ha Seed should not be planted deeper than 1 cm depth replanting bare patches Bare patches - depends on soil moisture One day after the field has sufficient moisture for germination, soak and incubate additional seed (e.g., 1 kg/ha) Three days after planting, broadcast additional seeds in problem areas. 15 to 20 days after planting transplant seedlings to bare patches Wet direct seeded Use Clean Seed - Increase yields by 5-20% Major issues: Seed germination and emergence - Seed burried under mud water has difficulty in emerging. Weed control Land levelling and early water management. Pests during crop establishment. Pre - germinate seed 48 hours before planting soak seed - change water for every four hours if possible After 24 hours, incubate seed in the shade - rinse if possible to avoid seed becoming too hot Seeding depth Target planting depth - <1cm if drilled - 0.5 cm (maximum 1 cm - Variety dependent) Surface seeding has fewer emergence problems than buried seed, but may have problems of birds and rats. Soil tilth Rule of thumb - the soil is ready for planting if a "V" made by dragging a stick through the prepared soil holds its shape. If the soil is too wet, the "V" will collapse indicating the seed will likely sink too deep and have problems of emergence. Seeding Wait 1-2 days after land preparation (depending on soil texture ) to avoid seed sinking too deep - deep seed will have problems emerging if covered by mud and water. Broadcast Seed rate - 80 to 120 kg seed/ha Anaerobically sow in row :Seed rate - 60 - 80 kg/ha Seed should not be planted deeper than 1cm depth Replanting bare patches One day after planting soak and incubate additional seed (e.g., 1 kg). Around three days after planting, broadcast additional seed in problem areas. 15 to 20 days after planting transplant seedlings to bare patches, if required. The following table summarizes the principal considerations in moving from transplanting to direct seeding. Wet direct seeded Dry direct seeded   No more nursery required No more nursery required No more seedling pulling No more seedling pulling Need to pre-germinate & incubate seed       - Need improved water management       - Need improved levelling       - Surface seed can be attacked by birds and rats Surface seed can be attacked by birds and rats Weed more problematic Weed much more problematic Seed planted too deep (>1cm) will have problems emerging       -

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Transplanted Rice Use Clean Seed -Increase yields by 5-20% Manual planting Plant in rows - generally with spacing of the order of 20 cm x 20 cm Mechanically plant Wait for 1-2 days after land preparation to avoid plants sinking too deep - deep planting will have problems of growing if covered by mud and water. Replanting bare patches 15 to 20 days after planting, transplant seedlings to bare patches Comparison of factors associated with different crop establishment methods Table key: TP = Transplanted; MTP = Mechanically transplanted; DDS = Dry Direct Seeded; WDS = wet Direct seeded (puddle soil); L=low, H=high; + = little problem; ++++ = major limitation. TP MTP DDS WDS Comments Cost L to H H L to H L to H Depends on labour markets Land management           Tillage     ++   Affects soil-seed contact Land leveling + ++++ +++ ++++ Low spots typically have serious problems of snails and of emergence in direct seeding Water management + +++ ++ +++ Drainage is critical in direct seeding. Use small canals around or through the field Leaching     ++   Greater problem if no puddling or subsoil compaction. Typically worse in dry direct seeded rice. Pests           Weed control + + +++ ++ Early seedling vigor and variety may decrease weeds through shading. Red/Weedy rice     +++ ++ Can be reduced by water seeding (e.g., California) and use of good seed Snails ++ ++   +++   Rats & birds     ++ ++   Variety           Lodging ++ ++ +++ +++ Especially as N rates are increased Early vigor     ++ ++ Especially for weed suppression Seedling requirements   ++       Pre-planting seed preparation       ++ Pre-germination is required and this can be a problem if seeding is delayed Soil factors           Soil texture + ++ ++ +++ Affects emergence and development of anaerobic conditions Soil- seed contact     +++ +   Depth to compaction layer   +++   ++ Affects machine mobility – e.g., transplanter or seeder Depth of planting     ++ +++ Problem of anaerobic emergence Rainfall during establishment     + +++ Effect worse on wet direct seeded and in heavier soils

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Crop uniformity For maximum yields, plant stand must be uniform across the field. Uniform seed and /or seedling distribution Good soil and water management - seeds will sink in soft soil and not emerge - or emerge unevenly Good land levelling Good water management, and Good control of pests during crop establishment

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Plant stand Target plant stands are related to the target panicle counts. Target panicle counts are those that will give optimum yields. For example, panicles/m2 for maximum yield are Dry Season Wet Season 500 - 600 350 - 400 N management and plant stand primarily drive tiller number. Example For a transplanted crop 2 plants/ hill @ 20 cm spacing, there are (5x 5 x 2) = 50 plants/m2. Thus, in the dry season each plant will need to produce 500/50=10 panicles/plant. The following table shows the tillering required attaining target panicle counts from different initial crop stands. Method Actual plant stand /m2 Plants/ m row Row Spacing Needed tillers/plant         Dry season Wet season Broad Cast 50 0.5   10-12 7-8 100 1   5-6 3.5-4 150 1.5   3.3-4 2.3-2.7 200 2   2.5-3 1.75-2 Direct seeded 50 7.5 12.5 10-12 7-8 100 15 25 5-6 3.5-4 150 22.5 37.5 3.3-4 2.3-2.7 200 30 50 2.5-3 1.75-2

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Seed Rate An obvious way to manipulate crop stand is through seed rate. For Example 10 Kg seed/ha = 400,000 seeds/ha = 40 seeds/m2 (@ a thousand grain weight of 25 g) Often less than 50% of seeds emerge, thus in the above example, 10 Kg would lead to <20 plants/m2 In direct seeded fields, farmers sow anywhere between 65 -200 Kg seed/ha, then the target number of panicles/ m2 become 500-600 for Dry season, and 350-400 for the Wet season. Seed rate Kg/ha Seeds/ m2 Probable emergence Tiller Dry season Tiller Wet season 60 240 <120 >4 >3 100 400 <200 >2.5 >1.8 140 640 <320 >1.6 >1.1 180 720 <360 >1.4 >1 220 880 <440 >1.1 <1

   

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Practices for increasing yield  How to increase the number of panicles  Raising healthy Seedlings Short and thick seedlings should be allowed to develop. It contains more roots and leaves for this purpose. For this to happen controlled supply of water is essential. The smaller the amount of irrigation water applied to the seedlings ,the shorter and thicker the seedlings. For this seedlings grown in upland are aptly suited. Another pre requisite for raising short and thick seedlings is the proper spacing of seedlings in the nursery. The wider the spacing the easier it is to obtain short and thick seedlings. But excessively wide spacing would require a very large area for the nursery and moreover it would make the pulling out of seedlings difficult. Proper fertilizer application is also necessary for raising short & thick seedlings. Optimum NPK applied to the nursery may be N- 10:P-13-15: K-15-17.(Kg/Ha) For controlling seedling diseases the seed should be treated with some fungicide so as to prevent the seed borne diseases. For controlling soil born diseases the field should be sterilized and well drained facilities should be maintained. Encouraging the practice of early season cultivation Cultivation starting under low temperature is quite essential. Vegetative growth periods can be lengthened . By lengthened vegetative growth period , one can effectively increase the number of panicles as well as resistance to rice plant against blast. Besides practicing early season cultivation one can grow rice under relatively low temperature conditions in temperate zone. A low temperature it self stimulates the growth point of stem and promotes tillering. Adequate basic fertilizers Panicle number will increase by using proper amount of fertilizers. Shallow transplanting In general, the shallower the seedlings are transplanted, the greater the number of tillers. When the seedlings are transplanted deeply the plant hills are liable not to spread out in the shape of a fan, but are liable to close, and then the closed type of the plant hill is ready to suppresses physical emergence of tillers. Secondly, the shallower the seedlings are transplanted, the closer the growth point comes to the ground surface. Hence, when the range of temperatures between day and night is increased, it results in promoting the emergence and development of tillers. Generally the longer the range of temperatures between day and night is, then more the number of tillers. Thirdly if the plants are transplanted shallowly, they absorb nutrients easily and increase the number of tillers. Because in the early stages of the rice plant the roots of plant are distributed in shallow layer of the soil, the temperature at the top layer is congenial for good absorption of nutrients than sub soil. Prevention of rooting damage after transplanting. In order to prevent rooting damage it is more important to use strong and stiff seedlings and to prevent breaking of the roots when up rooting them. Care should be taken that the seedlings should not wither after transplanting. Transplanting under relatively low air temperature, windless cloudy and rainy conditions favor rooting. Careful Management Inter tillage by removing the soil around the base of the plant hill by hand to make the hill spread out is particularly effective in promoting tillering. Top dressing with fertilizers 15-20 days after transplanting is more beneficial for tillering. Spacing Narrow spacing during transplantation will increases the number of panicle per unit area especially in sparingly fertilized paddy fields or in low-fertility fields, resulting in more yield than by practicing normal spacing. However narrow spacing tends to cause lodging. Narrow spacing is quite advantageous in "high yielding rice cultivation through ideal planting", Which ensures enough panicles at the early growth stage and restricts the nitrogen absorption by the plants at middle growth stage. Methods for suppressing non-bearing and weak tillers For controlling the non bearing tillers and weak tillers besides curtailing a basic application of nitrogenous fertilizers and avoiding "top-dressing just before or at the time of final emergence of bearing tillers, there are three other methods. Earthing up Spraying 2-4 D and MCPA Draining and drying up the soil. Spraying 2-4D, and MCPA just after the time of the final emergence of bearing tillers is not only use full for controlling weeds but is also effective in killing the small, weak tillers and new tiller buds in the rice plant it self. Hence if practiced in time it serves to kill two birds with one stone. Further the practice of earthing up by machine serves to shift the soil from the central portion of the space between the rows towards the hills so as to cover the bay of the hills and to close up the spreading tillers of each hill. As a result of this practice, the tillers are restricted. Mid season drainage (draining the field just before emergence of tillers) is effective to suppress non bearing tiller and to improve the root development. How to increase the number of grains per Panicle Controlling the development of an excessive number of panicles For increasing the number of grains per panicle, it is firstly desirable for the plant to avoid bearing an excessive number of panicles. Early seasonal cultivation, applying an optimum amount of fertilizer and stopping top dressings well before the time of the final emergence of bearing tillers, will lead to emergence of large and strong panicles. The earlier the emergence of tillers, the larger and stronger the panicles and the more effective is their contribution towards yield. Early application of fertilizers around 15-20 days after planting should be followed. Raising strong and large tillers by the time of neck-node differentiation Careful management at the time of neck- node differentiation by keeping the plant free from damage due to cold water irrigation, noxious insects and diseases, and all other unfavorable conditions. Promoting the position differentiation of grains (Spikelets) There are two ways of increasing number of grains per panicle. Positive way of increasing the number of differentiated spikelets, and a negative way of decreasing the number of degenerated spiklets. Application of fertilizer at the time of neck -node differentiation stage is necessary. As a result of it the number of primary & secondary rachis will be increased, and consequently the number of grains per panicle will be increased . Top dressing 25th day before heading shows better results. More over top dressing at the time of initial stage of spikelet differentiation is beneficial. In top dressing at neck node differentiation stage, fertilizer can be effectively applied especially nitrogenous fertilizer in most cases, particularly in the "AKIOCHI" paddy fields and in sandy fields with low fertility. Preventing the degeneration of spikelets One of the most common cause of degeneration of spikelets and the branches is nutrient deficiency (particularly N) in the period of reduction division. Hence top dressing just before and after the reduction division stage are found to be the most effective periods for increasing the percentage of ripened grains in the rice plant. How to increase percentage of ripened Grains Encouraging early season cultivation Large amount of deposition takes place before heading which serves to increase the percentage of ripened grains. So cultivate the crop as early as possible. To create favourable conditions during the period from young panicle initiation stage to full heading stage: Damage due to low temp should be avoided, frequent irrigations should be given at flowering and to decrease the water temperature. To prevent the production of an excess no. of spikelets: Not to apply excess N at neck node differentiation as it leads to more spikelets & number of grains ,but number of ripened grain will decrease. To make the rice plant reach it's heading time in healthy physical conditions: Early transplantations. Apply green manure crop . Top dressing with 'N' fertilizers at full heading stage: Nitrogen at this time promoted development of kernels by making the abortive kernels to develop fully which increases the percentage of ripened grains. To reduce damage caused by diseases and insect pests after heading. To prevent the plant ripening before the temperature drops in Autumn. How to increase the weight of 1000 grains: Enlargement to full size. Promote caryopsis development inside the hulls. It is necessary to enlarge the size of hulls for increasing size of kernel. To enlarge the size of hull it is essential to give the plant favorable conditions during secondary rachis to branch differentiation to terminal stage of the reduction division . It is to nourish the plant and to increase the activity during period, from the time just before the stage at which the spikelets are borne to terminal stage of reduction division at which , the size of the grain is completely determined.

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