By JOJO DE GUZMAN
SCIENCE CITY OF MUÑOZ, Nueva Ecija. — Rice experts disclosed
on Thursday new technologies to arrest the recurring problem on depletion of
nutrient which causes a loss in yield and an increase in cost.
Salvador Yabes, Philippine Rice Research Institute (PhilRice)
agronomist, said a formula that helps break the chain of nutrient depletion and
low yield is to apply the right kind and amount of nutrients at the right time.
PhilRice is a government-owned-and-controlled corporation
attached to the Department of Agriculture that aims to develope high-yielding
and cost-reducing technologies.
Simple tools are available that can assess nutrient
deficiency, guide fertilizer application, and generate savings in fertilizer
use, he said.
The PhilRice said that knowing and managing the nitrogen
needs of the plants can be based on the leaf color chart (LCC) while assessment
of the nutrients in the soil can be done through the use of minus-one element
technique (MOET).
Sufficient nutrients are needed by the plant at tillering,
early panicle initiation (EPI), and flowering to ensure good crop growth,
panicle development, and attainment of yield potential.
Nitrogen increases plant height, tiller number, leaf size,
spikelet number per panicle, percentage filled spikelets and grain protein
content. If nitrogen is deficient, plants become stunted and older leaves turn
yellowish.
As recommended, use LCC every 7 days from 14 days after
transplanting (DAT) or 21 days after seeding (DAS) until start of heading. Apply
one bag urea per hectare in wet season if LCC reading is below 4 for
transplanted and below 3 for direct wet-seeded rice. But ammonium sulfate is
used instead of urea when plants show sulfur deficiency.
In the MOET test, according to PhilRice experts, the soil
fertility status is assessed by monitoring plant nutrient deficiency symptoms
and growth response. Nitorgen, phosphorus, potassium, sulfur, zinc and copper
(Cu) are the nutrient elements that can be evaluated through MOET.
Phosphorus fertilizer, on the other hand, is important for
root development, tillering, early flowering and ripening. Phosphorus-deficient
plants are stunted with reduced tillering. Their leaves are narrow, short, very
erect, and dark green. Their stems are thin and plant development is retarded.
The number of leaves, panicles, and grains per panicle are also reduced.
Potassium improves root growth and plant vigor, helps prevent
lodging, and enhances crop resistance to pests and diseases. Potassium-deficient
plants are dark green with yellowish brown leaf margins. Dark brown spots can
also be seen on the leaf surface.
Sulfur is involved in the formation of plant vitamins and chlorophyll.
Similar to that of nitrogen deficiency, yellowing of leaves also occurs but,
younger leaves are the ones affected. Furthermore, symptoms like yellowish
seedlings in seedbed, high seedling mortality after transplanting, stunted
growth, reduced tiller number, fewer and shorter panicles, reduced number of
spikelets per panicle, and delayed maturity are due to sulfur deficiency.
