|Low-external Input Rice Production (IIRR, 292 p.)|
Traditional cultivars possess several attributes which make them indispensable for low-input rice production (LIRP). Among these characteristics include inherent resistance to certain pests and diseases, greater flexibility in the time seedlings can be transplanted, lower requirement for irrigation water and fertilizers and low seed-degeneration rate. Moreover, traditional cultivars have a higher (40%) market price than high-yielding varieties (HYVs). However, traditional cultivars which have characteristics, such as leafiness, tall stature; photoperiod sensitivity and susceptibility to lodge, usually have lower yield potential than HYVs. If a farmer would like to shift from planting HYVs to traditional cultivars, he should modify his practices to receive optimum output. Some cultural management practices that should be followed are:
1. Proper selection of cultivars. Study site characteristics (soil, climate) in order to select the bestsuited cultivars for the site:
· Assuming that there is enough water, select cultivars to
fit photoperiodic patterns. In the Philippines, short-day flowering rice
cultivars are best planted from August to September while long-day flowering
cultivars are best planted December to January.
· Select traditional cultivars which mature only 10-15 days longer than modern rice cultivars if long vegetative period is not wanted.
· Select semi-dwarf traditional cultivars (Pinili, Bengawan, Lubang, Abrigo, Improved Borong, Senador) to avoid lodging in typhoon-prone areas. If tall cultivars are used, some tillers should be cut before flowering to minimize lodging.
· Do not plant tall varieties in:
- soils of inherently high fertility swampy areas
- flood-prone areas
- areas with poor drainage
- sites with high weed infestation. Select for traditional cultivars those which have droopy and long leaves for more effective shading of the weeds. As in HYVs, the field should be kept weed-free 35-45 days after transplanting.
2. Alter the time of planting. Alter planting schedules to fit the climate in the area, specially the occurrence of typhoons and floods. The typhoon season for most parts of the Philippines usually occurs from June to September. Planting late (September) would be beneficial as grain filling and maturity will not coincide with the typhoon season. This also minimizes lodging.
3. Modify plant spacing and populations. Wider row spacing is recommended for traditional cultivars. Wider spacing lessens mutual shading, making plants sturdier end less prone to lodge.
The following row spacings are recommended for traditional cultivars:
0.25 x 0.25 m
0.30 x 0.20 m
0.30 x 0.25 m
0.25 x 0.20 m
Additionally, a 0.30 x 0.15 m spacing is convenient when rotary weeders are used.
Planting 1-2 seedlings/hill is recommended. This practice produces more productive tillers and tends to make plants less likely to lodge.
4. Practice good water management. Keeping rice continuously flooded makes stems more succulent, thus more susceptible to lodging. Traditional cultivars do not require continuous flooding during the vegetative period. However, it is beneficial to flood the field at flowering. Water is withdrawn once the hard dough stage is reached.
Infields with heavy weed infestation, irrigate the field 2-5 days after transplanting and gradually increase the water level. Water can be withdrawn once canopy closure is reached.
5. Reduce fertilizer use. Traditional cultivars do not require as much fertilizers as HYVs. Large doses of fertilizer make plants tall and prone to lodging.