Pravin Gautam

Document Type

Thesis - University Access Only

Award Date

2006

Degree Name

Master of Science (MS)

Department / School

Agronomy

Abstract

Though nitrogen (N) and phosphorus (P) are vital in several physiological and developmental processes in plants and animals, they pose several environmental, nutritional and health problems, if present in excess amounts. Reduction in the excess input of these nutrients into the soil, thereby reducing environmental problems and consequently nutritional and health problems, can be achieved by balancing their concentration in animal feed. Therefore, this research aims to quantify the N and P concentrations in the commercially adapted com hybrids in South Dakota and to determine if selection can be carried out for these traits to develop useful inbred lines; to determine the effect of planting densities on N and P concentrations and tonnage and dry matter (DM) yields. Ten hybrids were planted in randomized complete block design with three replications and two population densities (73390 plants/ha and 93900 plants/ha) at three locations (Brookings, Beresford and Watertown) during 2004 and 2005. Whole plants sampled at silage harvesting stage were analyzed for N, P and nitrate concentration. Hybrid differences based on pooled variance for percent phosphorus and nitrogen were significant. This indicates that successful selection for reduced N and P in these materials is likely. However, it is worthy to conduct multi location and multi years trials, as the hybrids did not perform consistently across environments. While high population density plants contained low mean P concentration in the environments having high mean P concentrations, there was no difference in mean N concentration between two planting populations. Tonnage and DM yields were highly dependent on hybrids' genetics but were altered by environments. Further, high density populations gave significant higher tonnage and OM yields than low density population, across all environments. P and N uptake were highly dependent on the OM yields and the plant P and N concentrations, respectively. Relative maturity days were not significantly correlated with any of the variables except plant stand percent. Hybrids 20601, N67-T4, N70-T9 and DKC54-51 were the better in terms of overall performance. On an average, they had P, N, and nitrate concentrations, P and N uptake on lower range; tonnage, OM yield, and plant stand percentage in the higher range. Hybrids 35y54, LG2489Bt and 34n43 were on the higher range of P, N and nitrate concentrations, and P and N uptake, variable in tonnage and OM yields, basically towards lower range. Based on the results, it seems that hybrids are genetically variable in terms of P, N and nitrate concentrations. Therefore, it is possible to carryout selection based on these parameters. However, effect of environments should be considered while establishing a selection program, as N and P concentration of plants interacts with the environmental effects. Further, selection based on N and P concentrations can be carried out without giving up the tonnage yields and OM yields. However, it is suggested to include more and diversified germplasm for further study.

Library of Congress Subject Headings

Hybrid corn -- South Dakota -- Analysis

Phosphorus

Nitrogen

Format

application/pdf

Number of Pages

103

Publisher

South Dakota State University

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