Evaluation of N, P and K Status of Wheat Using the Diagnosis and Recommendation Integrated System (DRIS) and the Physiological Diagnosis Chart

DIAGNOSIS and Recommendation Integrated System (DRIS) is a unique approach and a comprehensive system which identifies the nutritional factors mostly limiting crop production and improving fertilizer recommendations for obtaining high crop yields. The DRIS system depends on the principle of nutrient interrelationships in determining the order of the most limiting nutrients, as well as assessing the nutritional balance in plant. The current investigation aims at (i) Developing a database from which DRIS norms and indices of wheat grown on soils of Kalubia Governorate , Egypt, could be established and (ii) Defining the order of N, P and K requirements for plant using this method.
To achieve these objectives, 1000 samples of wheat plants grown on soils of the seven Kalubia’s counties were collected at shooting stage. The fresh and dry weights were recorded and samples were finely-ground and wet- ashed for N, P and K determinations. Grain yield of each field was also measured ( using 1.0 m2 plots). The 1000 observations were divided into high-yielding population (591 observations ; >2.4 Mg grains / fed., Mg = 106 g ) and low-yielding populations (409 observations). DRIS norms were calculated for the high-yielding population because the high yield usually results from balanced nutrients in plant. DRIS norms of n/p, n/k and k/p were calculated [being Σ(N/P)/n, Σ(N/K)/n, and Σ(K/P)/n, respectively; where N, P and K are percentages of the respective nutrients in plant, and n = the number of observations].
Calculated DRIS norms were 13.93, 1.40 and 10.25 for n/p, n/k and k/p, respectively and were almost comparable with those obtained by other researchers for wheat in other countries.
The N, P and K nutritional balance of wheat plants grown in Kalubia “semiarid region” tested by the DRIS approach show that nitrogen was the most limiting nutrient indicating high increasing requirements for high-yielding populations followed, by phosphorus. A high demand of P by these populations was proven as it came in the first and second order of limitation. Both nitrogen and phosphorus should be adequately covered through a sound fertilization program.
Thus, establishing DRIS norms for wheat is of a vital importance towards obtaining high yields. The DRIS norms could be used to test the nutritional balance of nutrients in plant and diagnose nutrient requirements through calculating DRIS indices or direct application of a proposed standard physiological diagnosis (PD) chart to the low-yielding populations. Research should be directed towards establishment of database from which DRIS norms for each of the most important strategic crops could be developed to assess the elements of obtaining high crop yield production.
The Diagnosis and Recommendation Integrated System