A humic acid improves growth of tomato seedling in solution culture

Abstract

The effects of humic acid (HA) on nutrient accumulation and growth of tomato seedlings were evaluated in a solution of limited nutrient availability in a greenhouse. HA additions were made to the nutrient solution at rates of 0, 640, 1280, or 2560 mg/L. The addition of 1280 mg/L HA produced significant increases in shoot accumulation of P, K, Ca, Mg, Fe, Mn, and Zn as well as increased accumulation of N, Ca, Fe, Zn, and Cu in roots. Fresh and dry weights of roots were also increased, However, on comparing nutrient accumulation in plants treated with 1280 mg/L HA and those given an additional supply of nutrients equivalent to those supplied by HA at the 1280 mg/L rate, shoots accumulated more N, P, K, Fe, and Cu, while roots accumulated more K and Ca. Therefore these increases do not appear to be associated with nutrients contained in HA. Eectrolyte leakage, as an indication of membrane permeability, did not differ as a consequence of HA additions. However, electrolyte leakage correlated positively with HA rate. A shift in solution pH from 5.8 to 7.0 had no effect upon on nutrient accumulation or growth of tomato seedlings. The interaction of pH and addition of HA was not significant 1. Partial funding for this research is from U.S.D.A.

Desenvolvimento das raízes do azevém cultivado em solução nutritiva completa, adicionada de substâncias húmicas, sob condições de casa de vegetação

“…As substâncias húmicas presentes na solução em dosagem mais elevadas apresentaram mais ligantes que os íons metálicos presentes na solução para poderem ser complexados e se tornarem menos disponíveis para as raízes das plantas, inibindo o desenvolvimento das mesmas (RHAUTHAN e SCHNITZER, 1981). Estas substâncias possibilitam maior desenvolvimento das raízes em cultivos em solução nutritiva que utilizem areia como substrato (DAVID et al, 1994;AYUSO et al, 1996;e SILVA et al, 1998c). Podem ser utilizadas na produção de forragem, flores, frutas e hortaliças em sistemas de produção hidropônicos e em fruticultura, floricultura e horticultura utilizando a técnica do gotejamento.…”

Effect of Phosphorus Level and Some Growth Regulators on Productivity of Faba Bean (Vicia Faba L.)

“…According to the data illustrated in the same The simulative effect of humic acid on macronutrients concentrations might be explained by David et al (1994) who indicated that humic acid enhanced cell permeability which in turn made more rapid entry of minerals into root cells and thus resulted in higher uptake of plant nutrients.…”

Foliar Spray of Nitrogen Fertilizer on Raised Bed Increases Yield of Transplanted Aman Rice over Conventional Method

“…Radioisotopes were used to show that foliar-applied fertilizers passed through the leaf cuticle and into the cells [2]. Various studies have shown that a small amount of nutrients (nitrogen, potash, or phosphate) applied by foliar spraying increases significantly the yield of crops [3][4][5][6][7][8][9][10].…”