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Document Type

Thesis - University Access Only

Award Date

1989

Degree Name

Master of Science (MS)

Department / School

Agronomy

First Advisor

Dale L. Reeves

Abstract

Residue on or near the soil surface is an effective means of reducing soil erosion. Tillage systems which leave residue on or near the soil surface are known as surface residue management systems. These systems include: no-till, ridge-till, strip-till, mulch-till, and reduced-till. According to the 1988 Soil Conservation Service survey for various types of conservation tillage acres, 33% of tillable acres in South Dakota were farmed by a surface residue management system. This figure is up from 19% in 1982 and will probably increase in the future as input costs rise. Seed planted in reduced tillage systems are in closer proximity to previous crop's residue than in conventional tillage systems. Studies indicate that crop residue can influence some growth aspects of the succeeding crop by the release of chemicals. This phenomenon. is known as allelopathy. Both inhibitory and stimulatory effects have been observed depending on species of receiving and producing plant. Chemicals released into the environment are called allelochemicals or phytotoxins (negative sense). Rice reported that Theophrastus observed the effects of allelopathy in 300 BC. He reported that chickpea (Cicer arietinum L.) did not improve soil as other legume crops did, but rather, exhausted it. Oat (Avena sativa L.) is an important small grain· feed and food crop. Planted in early spring, before row crops, oat is exposed to previous crop 's residue longer than many other spring-planted crops. Research on the effects of crop residues on oat seedling development may ultimately help to improve oat production under surface tillage management systems. Objectives of this study were to assess effects of aqueous extracts of crop residues on early growth of oat seedlings. A series of laboratory experiments were designed to determine: (1) growth response of oat seedlings to several crop residue extracts, (2) if extract characteristics such as osmotic potential and pH influenced oat seedling growth, (3) if germination temperature, seed size, seed age, and extract concentration have an effect on seedling response, and (4) if there are heritable genetic differences among genotypic responses to corn residue extracts.

Library of Congress Subject Headings

Oats -- Seedlings

Oats -- Genetics

Allelopathic agents

Format

application/pdf

Number of Pages

85

Publisher

South Dakota State University

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