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Pak. J. Bot., 45(3): 853-863, 2013.

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GROWTH DYNAMICS AND LEAF CHARACTERISTICS IN OATS (AVENA SATIVA L.) DIFFER AT EXCESSIVE NITROGEN AND PHOSPHORUS APPLICATION

AMANULLAH^1,2*, HIDAYATULLAH^1, AMANULLAH JAN¹ AND B.A. STEWART²

Abstract: Shoot-root ratio (by length), number of roots plant^-1 (NRPP),  number of tillers plant^-1 (NTPP), and leaf characteristics [number of leaves plant^-1 (NLPP), leaf length (LL), mean single leaf area (MSLA), leaf area plant^-1 (LAPP), leaf elongation rate (LER), leaf area index (LAI), specific leaf area (SLA), specific leaf weight (SLW), and leaf area ratio (LAR)]  response of oats (Avena sativa L., cv. Walker) was investigated under excessive nitrogen (N) as 200 mg N kg^-1 (N₁P₀), excessive phosphorus (P) as 200 mg P kg^-1 (N₀P₁), and combine 100 mg N + 100 mg P kg^-1 of potting mix (N₂P₂) and control (N₀P₀) as check in pot experiment at Dryland Agriculture Institute, West Texas A&M University, Canyon, Texas, USA during winter 2009-10. The experiment was performed in completely randomized design (CRD) with three replicates. Shoot-root ratio increased with excessive N, excessive P and combined N + P applications due to the decline in root lengths. The lower shoot-root ratio in control was mainly attributed to the longer roots produced by oats. Phosphorus alone or combined application with N (N₂P₂) increased NRPP over control. At the early stages, control had more NRPP than N alone. With advancement in crop growth, combined N + P applications had more favorable effects on NTPP than other treatments. Excessive P had more but excessive N had less NTPP than control. Except SLW, all other parameters viz. NLPP, LL, LER, MSLA, LAPP, LAI, SLA, and LAR decreased due the toxic effects of excessive N. Excessive P alone or combined N + P applications had beneficial effects on various leaf characteristics of oats viz. NLPP, LL, LER, MSLA, LAPP, LAI, SLA, and LAR.
 

¹Department of Agronomy, The University of Agriculture Peshawar, Pakistan-25130

²Dryland Agriculture Institute, West Texas A&M University, Canyon, Texas-USA

^*Corresponding author e-mail: amanullah@aup.edu.pk