RESPONSE OF MAIZE TO PHOSPHORUS SEED PRIMING

Abstract

A series of laboratory and field experiments were conducted to study the effect of phosphorus seed priming on emergence, seedling growth and yield of Maize (Zea mays L.) cv. Azam at the University of Agriculture, Peshawar, Agricultural Research Institute, Tarnab and Bangor University, Wales, UK during 2008 and 2009. Different sources of phosphorus (1 % P) including KH 2 PO 4 , SSP and DAP along with amended solutions of SSP (20 g l -1 KOH, 15 g l -1 NaOH and 12.5 g l -1 Na 2 CO 3 ) were used as priming treatments. Water primed and dry seed were used as control in the experiments. Seeds were primed for 16 h and then air- dried were sown in the mini plot and field for the seedling growth parameters and yield components. Seedlings from mini plot and field were cut at 21 days old stage. Laboratory tests were carried out on the P primed seeds labeled with P 33 to determine the amount of nutrient introgressed into and onto the seed. Germination test of water, P primed and non-primed seed was carried out in low P soil. P 33 labeled primed seeds were planted in tube pots to assess the P mobilization in seedling at three growth stages (7 days after emergence, 14 days after emergence and 21 days after emergence). Phosphorus priming of maize seed for 16 h reduced the time for germination. Three weeks old mini plot and field seedling grown from water, P or P amended solution primed seeds showed higher vigor than unprimed seeds as reflected in fresh and dry shoot weights, fresh shoot height and P shoot content as compared with non-primed seedlings. Additionally the nutrient uptake of seedling was increased due to 1 % P solution priming with KH 2 PO 4 . The seeds primed with P 33 labeled solutions (KH 2 PO 4 ,SSP, and SSP+20 g l -1 KOH) were also used to study the P mobilization in the seedling on three different stages (7 DAE, 14 DAE and 21 DAE) using tube pots. Leaf and root P data showed that phosphorus was effectively mobilized inside the plant due to priming on low P soil and hence helped in reducing the P deficiency in maize to some extent. Data for nutrient introgression by seed revealed that maize seed had introgressed significant amount of P through priming. Also that surface washing of the primed seed only removed 29 % of P from the seed coat. Yield parameters showed positive response to P priming as reflected in cobs yield (126% increased over control), grain and straw yields (85 % and 94% increase over control, respectively), thousand grain weight and P content of grain. Priming maize with SSP + 20 g l -1 KOH showed almost same effect as of KH 2 PO 4 . It was concluded that priming maize with SSP + 20 g l -1 KOH would be effective alternative of KH 2 PO 4 as SSP is generally used fertilizer and KOH is also easily available. This would be easier and cheaper source of priming for resource-poor farmers.