Blueberries

A Century of Research

Ronald Korcak

• Publisher: Routledge
• Year: 2018
• ISBN:
  9781351463423
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Botany
• Index: Biological Sciences

Blueberries: A Century of Research presents the results of basic and applied research into blueberry science and culture around the world. It contains technical reports on genetics, nutrition, physiology, culture, and harvesting of several blueberry species. Readers will find much current, helpful, and interesting information for their work with blueberries.General areas covered in the book are the blueberry culture and its future, blueberry genetics and diseases, blueberry nutrition, and blueberry fruit quality. Specific chapters address a variety of topics including:

• utilization of wild blueberry germplasm
• use of sparkleberry in breeding highbush cultivars
• identification of markers linked to genes controlling chilling requirement and cold hardiness
• detection of blueberry scorch virus and red ringspot virus
• methods of controlling blueberry gall midge damage
• control of bunchberry in wild blueberry fields
• blueberry nitrate reductase activity
• use of gibberellic acid as a management tool for increasing yield of rabbiteye blueberry
• blueberry culture and research in Japan

In Blueberries: A Century of Research, small fruit researchers, extension workers, and blueberry specialists will find important new information for continued improvement of blueberry culture and specialization. The book is a vital resource that appeals to a professional audience worldwide.

---

SECTION V:
Blueberry Nutrition

Moderator: Jim Spiers

---

Organic Matter and Nitrogen Level Effects on Mycorrhizal Infection in ‘Bluecrop’ Highbush Blueberry Plants

Barbara L. Goulart

Kathleen Demchak

Wei Qiang Yang

SUMMARY. A field planting of ‘Bluecrop’ highbush blueberry was established in spring of 1992 to evaluate the effects of various cultural practices on plant growth and mycorrhizal level. Treatments included mulch or no mulch, pre-plant amendment or no pre-plant amendment, and 4 levels of nitrogen fertilization (from 0 to 100 g/plant in year 2, and from 0–120 g/plant in year 3) arranged in a complete factorial experiment. After two years, interactions among the treatments characterized the plant’s responses. When no mulch was employed, increasing nitrogen level resulted in decreased mycorrhizal concentration in the roots. When plants were mulched, effects were inconsistent. Mulch and/or amendment increased plant growth and vigor. For plants with no mulch and no amendment, canopy volume and mycorrhizal concentration level decreased with increasing nitrogen. [Article copies available from The Haworth Document Delivery Service: 1-800-342-9678.]

KEYWORDS: Highbush blueberry; Vaccinium corymbosum; Nutrition; Nitrogen; Fertilizationl Symbiosis; Ericoid mycorrhizae; Organic matter; Mulches; Soil amendment; Hymenoscyphus ericae

INTRODUCTION

Highbush blueberry roots, like those of most ericaceous plants, host a fungal symbiont which increases the plant’s ability to forage for nutrients, most notably nitrogen. The fungi benefit from this relationship because it utilizes the host plant’s photosynthates as its carbohydrate source. The fungal symbiont, usually an ascomycete for ericaceous plants, infects the root and forms mycorrhizae (which literally means “fungus roots”). While many studies have been conducted on the effects of organic matter (both pre-plant and as a mulch) and nitrogen form and level on blueberries, and some studies have been conducted on the effect or level of mycorrhizal infection on blueberries, none of these studies have reported the relationship between nutrition and planting practices with the level of mycorrhizal infection.

Organic matter and nitrogen studies. Soil amendments for preplant incorporation improve blueberry establishment and production on mineral soils. Perlmutter and Darrow (1942) found that blueberry seedlings grew best in a media that was 2/3 “forest litter” and 1/3 soil. More recently, Odneal and Kaps (1990) found that aged or fresh pine bark was as good as sphagnum peat for preplant incorporation, with no differences in plant height, spread, number of canes or plant yield or size. Rotted sawdust in the planting hole has also proven to be a good material for preplant incorporation (Eck, 1988).

Mulches are considered essential for blueberry production on mineral soils. Numerous studies have been undertaken to evaluate the effect of mulches. On rabbiteye blueberries grown on a fine sandy loam, mulching increased plant height, and shoot and root weights (Patten et al., 1988). Many researchers have examined different types of mulches for their effectiveness. Savage (1942) found that 8 cm (3 in) of sawdust mulch (at least 1 year old) was superior to rye straw or oak leaf mulches, with better plant survival and growth. All mulches, however, were notably better than clean cultivation. Skiruin and Otterbacher (1984, 1986, 1987) and Meador et al. (1984) have found that many mulching materials work well. Sawdust and chopped corn stalks were particularly effective. Leaf mulch (of oak, locust, beech, maple, sycamore and some pine needles) also performed as well as sawdust and chopped corn stalks, but had to be replenished yearly rather than once every two years. All mulches were aged 1–2 years. Wood chips and straw produced the lowest yields and shortest plants. Pine bark and well composted manure or stable bedding have been reported to work well (Eck, 1988), however, the latter materials may increase soil pH. Korcak (1988) cites the reasons for improved performance using organic mulches as improved water-holding capacity, reduced temperature fluctuations, weed control and improved soil tilth. Mulches also maintain a more constant media pH, and in some cases contribute to acidification of the soil.

A study by Spiers (1986) found that on rabbiteye blueberries, mulch was the most important component, followed by incorporated peatmoss and irrigation. Mulching resulted in a uniform root distribution from the plant crown outward, with most roots in the upper 15 cm (6 in) of soil. Incorporated peatmoss tended to concentrate the root system near the crown area (most at the 30–45 cm [12 to 18 in] depth). After three years, all of the plants that had received none of the treatments (no mulch, peat moss or irrigation) had died.

Recommended levels of nitrogen fertilizer application for mineral soils are between 45 and 91 kg of actual nitrogen/ha (40 and 82 lbs of actual nitrogen/A) (urea or ammonium sulfate) depending upon plant age (Goulart et al., 1994). There has been considerable debate regarding the nitrogen form utilized by highbush blueberry plants (Townsend, 1967; Hammett and Ballinger, 1972; Rosen et al., 1990). Most studies conclude that there is preferential utilization of ammonium nitrogen by Vaccinium, making it an unusual species, since most plants prefer to take up nitrate nitrogen (Peterson et al., 1988; Townsend, 1967; Merhaut and Darnell, unpublished). Studies on Calluna vulgaris and Vaccinium macrocarpon resulted in increased total N, increased N concentration in the shoot, and increased shoot growth on mycorrhizal versus non-mycorrhizal plants (Read and Stribley, 1973; Stribley and Read, 1974). Mycorrhizal plants also contained more total nitrogen than non-mycorrhizal plants, suggesting that the mycorrhizal plants were better able to utilize non-ammonium sources of nitrogen than non-mycorrhizal plants (Stribley and Read, 1974). Other research demonstrated that ericoid mycorrhizae can assimilate amino acids, peptides and proteins from the soil, and transfer N from these sources to host plants, providing an additional source of N which plants otherwis...