Heterosis for Nitrogen, Phosphorus and Potassium in Leaves and Their Relationship with Heterosis for Yield in Upland Cotton (Gossypium Hirsutum L.)

The divers ypes of cotton and their ivegenote crosses have been assessed for nitrogen, phosphorus and potassium accumulation in leaves at three stages of growth viz., flowering (S₁), 50 per cent boll bearing (S₂) and first boll opening (S₂) Accumulation of all the three nutrients invariably increased with advancement of stages of growth. These attributes were under the genetic control. The nitrogen content of J 34, the highest yielding genotype, was one of the poorest, meaning thereby that the sink of this variety was highest. None of the hybrids exhibited heterosis for low nitrogen content at flowering stage. This is probably the reason of not getting heterotic effect for yield by any of the hybrids investigated. The parents were poor combiners for three trails studied. Low and negative association of nitrogen accumulation in leaves at flowering stage with yield was observed. On the contary, higher accumulation of phosphorus and potassium at latter stages of plant growth have been found to be related with high seed-cotton yield.