Читать книгу Dry Beans and Pulses Production, Processing, and Nutrition - Группа авторов - Страница 35

Dry bean yields from the onset of early breeding efforts in the early 1900s to now have seen just less than 1% yield gain per year, a value commonly reported for soybean (Figure 2.2). In most crops, yield gains are attributed equally to changes in genetics and management and a similar combination of management and genetic factors contributed to bean yields. Periods of increasing yield gains and lulls have occurred along the way. A plateau with 1500 kg/ha average yields occurred from 1960–1979, followed by a modest upward trend to 1900 kg/ha in 2000. Since 2000, yields have oscillated around 1900 kg/ha even though higher yielding varieties have been released (Vandemark et al. 2014). The movement of production from highly productive hectares grown under irrigation in the western US (a 50% decline) to less productive regions in North Dakota the last 20 years, has likely contributed to the recent lull in yields and a perceived lack of genetic yield gains.

A major wake‐up call for bean breeders in the US came in the 1972 report on genetic vulnerability of crops published by the National Academy of Sciences (NRC 1972) that emphasized the need for greater genetic diversity to combat genetic vulnerability. Prior to the 1980s, the seven bean‐breeding programs across the US were small, isolated efforts (Table 2.1). These programs focused largely on local needs in a range of diverse seed types that resulted in limited exchange and use of bean germplasm from other programs. Many programs expanded breeding and testing programs in that era, as the need to change the status quo was obvious. The positive genetic changes resulted from the use of wider crosses that exploited greater genetic diversity and improved germplasm from other programs. The International Center – CIAT, established in the late 1960s in Cali Colombia was an important new source of wider genetic diversity of improved germplasm during this time. In 1973, CIAT sponsored a conference on ways to enhance the “Potential of field beans and other legumes in Latin America.” The approach of using “Plant architecture and physiological efficiency in the field bean” (Adams 1973) to enhance yields opened the door to new breeding approaches, and the development of new architectural types with broader adaptation and higher yield potential (Adams 1982; Kelly 2000). The liberal use and exchange of materials between CIAT and US breeding programs revitalized many of these programs. In addition, funding from Rockefeller Foundation in the mid‐1970s also encouraged the utilization of new germplasm, which led eventually to the establishment of USAID funding of the Bean/Cowpea Collaborative Research Support Program (B/C CRSP) project in 1980 (Adams 2003). The B/C CRSP and recent iterations, the Feed the Future (FtF) Pulse CRSP; Legume Systems Innovation Lab (FtF 2021a); and USDA‐ARS Bean Research Team (FtF 2021b) projects have not only encouraged better longstanding integration among breeding programs in the US, but among many institutions in the Caribbean, Latin America, and Eastern and Southern Africa, where the common currency was germplasm exchange and utilization. For example, landrace bean germplasm from Malawi was introduced for testing in Michigan (Martin and Adams 1987) and added to the National Plant Germplasm collection. A summary of the new varieties developed through these different CRSP programs in a number of countries including the US was published by Beaver et al. (2003, 2020).

Fig. 2.2. Dry Bean yields (kg/ha) in the US over 110 years since 1909.

Source: Updated from Vandemark et al. (2014) using USDA‐NASS (2020b) data.

Table 2.1. Major bean breeding programs in the US, location and seed type focus prior to 1980.

Institution	State	Seed types	Breeders
Cornell	NY	Light red kidney, black	D. Wallace
MSU	MI	Navy, dark, light red kidney	M.W. Adams
UNL	NE	Great northern	D.P. Coyne
CSU	CO	Pinto	D. Woods
UI	ID	Pinto, pink	J. Kolar, M. LeBaron
USDA‐ARS	WA	Small red, pink	D. Burke
UCD	CA	Kidney, pink, cranberry	C. Tucker