Influence of potassium nutrition on leaf area index in cotton (Gossypium hirsutum L.) under an arid environment

A field experiment was conducted at Central Cotton Research Institute, Multan, Pakistan to study the effects of potassium nutrition on leaf area index in cotton (Gossypium hirsutum L.) The treatments consisted of four cotton cultivars (CIM-448, CIM-1100, Karishma, S-12), four potassium-rates (0, 62.5, 125.0, 250.0 kg K ha-1) and two sources of potassium-fertilizer [potassium chloride (KCI), potassium sulphate (K2SO4)]. During the early part of the season, leaf area index progressed slowly and required 60 days to reach at 1.5 and then it reached at 4.02 within next 30 days. Thereafter, it declined gradually to minimums of 0.62 at maturity. Cultivar CIM-1100 maintained the highest leaf area index compared to other cultivars. Leaf area index increased with concurrent increase in potassium-levels. The regression analysis indicated a highly significant relationship (r = 0.94**) between potassium levels and leaf area index. Addition of potassium fertilizer in the form of potassium sulphate showed an edge over potassium chloride. There were highly significant (p less than 0.01) relationships between leaf area index and number of total fruit, number of bolls per plant, plant height, total dry weights and leaf dry weights.