Weed

• Term 1^st used by Jethro Tull.
• Book à “Horse Hoe Husbandry”

Weed dispersal by wind

1. Pappus : Parachute like modification of calyx into hairs. i.e. composite family.
2. Comose: Weed seeds with hairs. i.e. calotropis spp.

• Allelochemicals secreted by weed is called kaolines.
• Rice is able to survive in rich water due to parenchymatous tissue.
• Rice straw contains more K than its grain which is reverse to other cereals.
• Out of 24 species of rice, only 2 are cultivated.

Note:

1. Indica : India
2. Japonica : Japan
3. Javonica : Indonesia

• Flooding of soil in rice causes

a) increase in P, Si and Mo

b) Decrease in water soluble Zn and Cu.

• DAP is excellent fertilizer for basal dressing in paddy fields.