Phosphorus Nutrition Influences Plant Water Status, Mineral Distribution, Dry Matter and Yield of Marigold under Saline Environments

摘要

The plants of marigold (Tagetes erecta L.) cv. African Double Giant were raised in earthen pots containing dune sand, at four salinity levels (ECe 2, 4, 6 and 8 dS m~(-1)), each predominated by chloride (Cl: SO_4 = 7:3) and sulphate (Cl: SO_4 = 3:7) salts separately under natural conditions of screenhouse. Each ECe treatment including a nonsaline control (ECe 1.15 dS m~(-1)) was established at four levels of added P (0, 30, 60 and 90 mg kg~(-1) soil) with the objective to study the changes in plant water status, mineral distribution, growth and yield. Under salinity, the osmotic potential (V_s) and relative water content (RWC) decreased significantly, while a sharp rise in proline and total soluble carbohydrates of leaves was observed. A considerable decrease in plant water status, potassium and P uptake and increase in sodium and chloride under salinity were noticed. Different levels of salinity showed significant negative correlation with dry matter R~2 = 0.978(C1), 0.976 (SO_4) and fresh weight of flowers plant~(-1) R~2= 0.997 (Cl), 0.990 (SO_4). These adverse effects of saline environments were ameliorated by P nutrition and for that the optimum dose of P application in SO_4-salinity and Cl-salinity was 60 and 90 mg kg~(-1) soil, respectively. Regression equation indicated that magnitude of increase in dry matter of plant and fresh weight of flowers with respect to P application was significantly better in Cl than SO_4-salinity. Cl-dominated soils were better responsive to added P. In absence of P, the plants were failed to survive after two months of transplanting at ECe of 8 dS m~(-1) irrespective of types of salinity and at ECe of 6 dS m~(-1) in Cl-salinity.