Akhter, Naheed: Comparison of DRIS and critical level approach for evaluating nutrition status of wheat in District Hyderabad, Pakistan. - Bonn, 2012. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5n-26385
@phdthesis{handle:20.500.11811/5092,
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5n-26385,
author = {{Naheed Akhter}},
title = {Comparison of DRIS and critical level approach for evaluating nutrition status of wheat in District Hyderabad, Pakistan},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2012,
month = mar,

note = {Intensive cropping systems, improper use of fertilizers or no fertilizer application, and unreliable and poor quality of irrigation water have led to declining soil fertility in the district of Hyderabad, Pakistan. To date, no comprehensive overview exists on the nutrient status of the soils in the region and on yield constraints due to mineral nutrient deficiencies or imbalances. The objectives of this study were to a) determine the nutritional factors limiting productivity of wheat in Hyderabad, Pakistan, b) compare the DRIS and critical level approach for evaluating nutrient deficiencies in wheat, and c) identify the most limiting nutrient(s) that should be applied to increase and stabilize the yield of wheat in the region. Farmers’ fields (181) were selected on the basis of a survey of wheat-growing areas. Low- and high-yielding areas for two vegetation seasons (2007-08 and 2008-09) with different crop production management were selected. Plant sampling of wheat was done for shoot material at GS-29 (tillering stage) and for leaf tissue at GS-39 (emergence of flag leaf; Zadok et al. 1974). Sample analysis included the determination of macronutrients (N, P, K) and micronutrients (Zn, Cu, Fe, Mn, and B). For yield estimates at harvest, data on grains per spike, number of spikelets and thousand-grain weight were collected. Yield data were divided into low-and high-yielding populations according to the Cate and Nelson (1971) procedure for partitioning. The mean value and coefficient of variance were calculated for DRIS norms. The selected DRIS norms were: N/P, N/K, N/Cu, N/Fe, N/Mn, N/Zn, N/B, P/K, P/Cu, P/Fe, P/Mn, P/Zn, P/B, K/Cu, K/Fe, K/Mn, K/Zn, K/B, Cu/Fe, Cu/Mn, Cu/Zn, Cu/B, Fe/Mn, Fe/Zn, Fe/B, Mn/Zn, Mn/B and Zn/B. The DRIS indices were established for N, P, K, Zn, Fe, Cu, and B of the low- and high-yielding populations. These indices were compared with the developed norms. The interpretation of the wheat nutrients was done using the nutritional balance index (NBI) approach.
The average index value for N at GS-39 is +47.04, which indicates that N is sufficient in the leaf tissue. The values of P and K are 58.49 and 21.67, respectively. These positive values show that N, P and K are sufficient in the leaf tissue, and that the wheat plants do not require any additional fertilization. The micronutrients are almost in good balance, i.e., neither sufficient nor deficient except for Fe. The index value of Fe is -93, whereas the index values for Mn, Zn, Cu, and B are -21.88, +17.77, -1.38 and -28.68, respectively. The NBI is 56.45, which shows that there is no high nutritional imbalance. The interpretation of the data with respect to deficiency and adequate and moderate supply shows that all nutrients are adequately supplied with exception of Zn and B, which show high values. However, the average index values of the shoot material at GS-29 are different; here the value for N is -54.27, which indicates that N is deficient at this growth stage. The same applies to P and K. The micronutrient values, however, are positive. This indicates that these nutrients are not in short supply compared to the macronutrients. The NBI is 75.23, which shows some nutritional imbalance.
According the results of the critical level approach, the average concentration of N in the leaf tissue at GS-39 is deficient (which is in contrast to the DRIS evaluation), whereas all other nutrients are adequate. The average nutrient concentration in the shoot material at GS-29 is similar to that in the leaf at GS 39. The DRIS calculation also indicates that N is in short supply at the early growth stage, whereas Mn and B are present in high concentrations. Statistically, the values in the critical level approach are non-significant compared to those of the DRIS. However, DRIS has an advantage, as the DRIS norms for the study area are similar at both studied growth stages, which makes the interpretation easier. It has to be stressed, though, that the DRIS only indicates nutrient supply in relation to the other nutrients. According to the DRIS evaluation, if the N supply is improved during early development, other nutrients may become yield limiting, e.g., P and K. The DRIS norms can provide guidelines for the policy makers in the region regarding recommendations for appropriate fertilizer application.},

url = {http://hdl.handle.net/20.500.11811/5092}
}

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