Bradbrook - 2012 - Rice Farming complete with methods to increase ric

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e. Leaf color chart Source: IRRl.org The nitrogen content of a plant can be easily monitored using a standardized LCC to check a leafs shade of green. This chart was developed from the collaboration between IRJU and the Lfniversity of California Cooperative Extension. The chart is made of a white plastic strip with four panels of different shades of green (from yellowish to dark). Each shade corresponds to a specific amount of N in the plant. To determine if the rice plants need supplemental N, first a sample of ten healthy rice plants or hills are randomly selected. The topmost, fully expanded leaf from each plant is removed and the middle portion of the leaf is used to locate the panel color that closely matches that of the leaf. If the leaf color falls between Panels 3 and 4, then supplemental nitrogen is not needed. If the color falls below Panel 3, then the soil is nitrogen-deficient and must be supplemented. Panel 5 indicates excess nitrogen. In this case, fertilization should be withheld. Leaf color readings should always be conducted at a specified time of day, and they must be done in the shade because direct sunlight affects leaf color reading. f. Micronutrients important to rice plant growth Zinc deficiency is common in sodic soils with high pH or when the soil or water that is used for irrigation contains high amounts of bicarbonate. It is considered as the most prevalent deficiency of any micronutrient in rice. The symptoms of zinc deficiency include stunted plants, brovm spots on leaves, basal leaf chlorosis, stacking of leaf sheaths, slow growth, and reduced tillering. During the reproductive stage, increased sterility of the spikelets may occur. To correct zinc deficiency, zinc sulfate can be applied to the field at 5 kg per hectare 14 days before transplanting. Alternatively, seedlings may be treated with 35
1 zinc sulfate while still in the nursery beds or dipped in a 2 to 4 % zinc oxide suspension prior to transplanting. If the deficiency is observed after transplanting, the field should be drained and the soil allowed to dry up. When transplants exhibit new shoot and root growth, 2.5 kg per hectare of zinc EDTA or 5 to 6 kg per hectare of zinc complexes should be applied. Ammonium sulfate is then added at a rate of 50 kg per hectare and shallow flooding of the field is done. Doing this salvage measure may lengthen the growing season by two to three weeks, but the rice plants can still attain as much as 90% of their yield potential. Iron deficiency is characterized by stunted plants with chlorotic or yellowing leaves. Young leaves exhibit interveinal yellowing. The occurrence of this deficiency is quite rare but correcting it is a very expensive undertaking; to be effective, large amounts of inorganic iron sources are needed. Nonetheless, if found deficient, 30 kg per hectare of FeS04 should be applied close to the rows or broadcasted (requires a larger amount). A 2 to 3% solution of FeS04 or iron chelates can be sprayed on the leaves two to three times at two-week intervals starting at tillering. Chlorotic young leaves with necrotic tips, whereas older leaves exhibit no necrosis are the symptoms of sulfur deficiency. When the deficiency occurs during the vegetative stage, the effect on yield is more pronounced. Sulfur-deficient soils can be corrected by application of 2.5 to 3 kg of S per hectare per ton of anticipated yield 14 days before transplanting. There are other micronutrients that are important to rice. It is best to consult existing literature when deficiency symptoms do not match the deficiencies detailed above. 3. Weed management Weed management should begin during land preparation, three to four weeks before sowing or transplanting. The land must be kept dry prior to land preparation so that weed seeds will dry up. Weed seeds that do germinate are allowed to grow, then they can be incorporated into the soil during plowing or harrowing. This method effectively reduces weed seed reserves in the soil resulting in lower infestation in the following growing cycle.
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Page 7 and 8: Section 4: Post-harvest Processing
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Page 39 and 40: In both upland and lowland rice cul
Page 41 and 42: Combating disease attack involves h
Page 43 and 44: í The best time to apply fungicide
Page 45 and 46: 7. The Economic Threshold The econo
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Page 59 and 60: 2. Befare planting: a. Establish ta
Page 61 and 62: temperatures. Key Check: Phosphorus
Page 63 and 64: 2. Requires data-gathering skills:
Page 65 and 66: 1. Sun drying This drying method is
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Page 69 and 70: not commercially viable, b. Single
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