ISSUE 6   June 17, 2010

DRY BEAN TYPES AND DEVELOPMENT STAGES

In dry edible bean there are basically two plant types, determinate (bush) or indeterminate (vining or trailing). For example, navy beans or pinto beans may be either of the bush or vining type. In the determinate type, stem elongation ceases when the terminal flower on the main stem or lateral branches have developed. In indeterminate types, flowering and pod fill will continue as long as temperature and moisture conditions are favorable for plant growth .

In addition to the distinction between determinate and indeterminate plant types, four plant growth habits have been identified. These are: Type I Determinate bush; Type II Upright short vine, narrow plant profile, three to four stems; Type III Indeterminate, prostrate vine; Type IV Indeterminate with strong climbing ability. These growth habits have become useful in identification and classification of new upright bean cultivars. Upright plant growth habit and architecture increase the efficiency of direct harvest of dry beans The challenge for breeders has been to develop cultivars with upright architecture, while maintaining high yield potential. The recent NDSU pinto cultivar releases Lariat and Stampede have an improved upright architecture (Type II) with increased yield potential. In contrast the cultivar Maverick is a Type III-prostrate indeterminate pinto bean.

Plant development for both determinate and indeterminate plant types has been divided into vegetative (V) and reproductive (R) stages as indicated in Table 1.

Vegetative stages are determined by counting the number of fully expanded trifoliolate leaves on the main stem. Reproductive stages are described by pod and seed characters. The first pod developing on the plant is described and followed to full size. At the time of first bloom (R stage), secondary branching begins in the axis of lower nodes which will produce secondary groups of blooms or pods. To determine the growth state it is important to follow the main stem, which is readily discernible on both determinate and indeterminate plants. A trifoliolate is counted when it is fully unfolded.

Table1. Stages of vegetative and reproductive development in an indeterminate (Type III) dry bean.

Stage

General Description
Vegetative Stages

Days from planting

VE

Hypocotyl emergence.

7

VC

Cotyledonary and unifoliolate leaves visible.

10

V1

First trifoliolate leaf unfolded

14

V2

Second trifoliolate leaf unfolded.

20

V3

Third trifoliolate leaf unfolded Secondary branching begins to show from branch of V1.

26

V(n)

n trifoliolates on the main stem, but with blossom clusters still not visibly opened.

A new node each 3 days

V8

Vine (indeterminate) plants may begin to exhibit blossom and become stage R1.

40

 

Reproductive Stages

 

R1

One blossom open at any node. Tendril will begin to show.

40

R2

Pods 1/2 inch long at first blossom position (node 2 to 5 most plants).

43

R3

Pods 1 inch long at first blossom position.

46

R4

Pods 2 inches long at first blossom position.

50

R5

Pods 3 plus inches long, seeds discernible by feel.

56

R6

Pods 4.5 inches long with spurs (maximum length). Seeds at least 1/4 inch long axis.

60

R7

Oldest pods have fully developed green seeds. Other parts of plant will have full length pods with seeds near same size. Pods to the top and blossom on tendril, nodes 10-13.

70

R8

Leaves yellowing over half of plant, very few small new pods/blossom developing, small pods may be drying. Point of maximum production has been reached.

82

R9

Mature, at least 80% of the pods showing yellow and mostly ripe. Only 30% of leaves are still green.

94

Hans Kandel
Extension Agronomist - broadleaf crops
hans.kandel@ndsu.edu


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