VENUGOPALAN M.V., BLAISE D., TIWARY P., SINGH J.
Abstract
The response pattern and productivity trends of monocropping
systems involving upland (Gossypium hirsutum) and tree (Gossypium arboreum)
cotton, under different N, P and K combinations with and without FYM (Farm Yard
Manure), on rainfed vertisols, were quantified from data generated through a
long term field experiment. Using daily rainfall data, the rainfall distributed
during physiologically critical phenophases were partitioned and their effect
on the productivity of G. hirsutum and G. arboreum was studied. Results indicated
that monocropping systems with N alone are not sustainable and annual addition
of at least 13 kg P and 5 Mg FYM ha-1 imparted stability and sustainability.
Mono cropping of G. arboreum out yielded mono cropping of G. hirsutum in 13
out of 15 years except in years of heavy rainfall. Annual variations in the
quantum and distribution of rainfall, resulted in high coefficient of variation
and differentially influenced nutrient responses, obscuring all but extreme
yield trends estimated using linear regression analysis. The quadratic relationship
fitted between yield and rainfall during the phase from squaring to boll formation
was significant in both the species indicating that rainfall distribution during
this period has a profound influence on cotton yield. The optimum rainfall during
this phase was around 280-290 mm.
Keywords:
Gossypium hirsutum, Gossypium arboreum, productivity trends,
rainfall, rainfed, nutrient management