Abstract
Tepary bean is gaining interest around the world as a dryland field crop. A two-year field experiment was conducted to determine the effect of plant spacing on the agronomic performance and fodder quality of the crop. A split-plot design was used with three replications, four cultivars (GK010, GK011, GK012, and Motsumi) were assigned to main plots, while subplots were three intrarow plant spacing (10 cm, 20 cm, and 30 cm). Four agronomic variables and eight chemical compositions, including in vitro dry matter digestibility (IVDMD) of husk, stem, and leaf, were measured. Spacing significantly ( P < 0.05 ) influenced plant biomass, pod yield, harvest index, and seed yield, while cultivar affected only pod yield and seed yield. Plant biomass increased with plant spacing where 10 cm produced 936 kg/ha; 20 cm, 750 kg/ha; and 30 cm, 611 kg/ha for 2015–2016 while 10, 20, and 30 cm were observed for 1568 kg/ha, 1135 kg/ha, and 889 kg/ha, respectively, in 2016–2017 season. These trends are attributed to the higher plant population in the narrow row spacing. GK012 consistently outperformed other cultivars for plant biomass, pod yield, and seed yield and has a potential for further selection. Fodder nutritive qualities were not affected by cultivar, while spacing only influenced IVDMD. The three plant parts were significantly ( P < 0.05 ) different for all the nutritive qualities. Leaves had significantly ( P < 0.05 ) lower values of ADF, CF, and NDF compared to those of stem and husk an indication of relatively higher digestibility of the leaf. Acid detergent fiber (40%), neutral detergent fiber (53.65%), crude fiber (35.45%), ash content (12.29%), dry matter (93.09%), and IVDMD (70.66%) were recorded. This study revealed that tepary bean forage has good nutritional content, except for the low phosphorus level. For higher agronomic performance, tepary cultivars should be planted at a spacing of 10 cm without compromising forage quality.
Highlights
Legumes are key components in mixed crop-livestock systems; they provide nutritious grains for food and haulms for fodder and improve soil fertility through nitrogen fixation [1].Tepary bean (Phaseolus acutifolius) originally from the arid and semiarid environments of northwestern Mexico and the southwestern United States of America is an important legume crop [2, 3]
Our findings revealed that plant spacing significantly (P < 0.001) influenced plant biomass, pod yield, harvest index, and seed yield, while cultivar significantly (P < 0.01) affected pod yield and seed yield. e interaction between spacing and cultivar did not affect any character, while interaction between spacing and year only affected harvest index (Table 2), indicating a lack of stability on the index
Plant spacing indicated that a narrow spacing of 10 cm produced higher plant biomass, pod yield, and seed yield, followed by the medium spacing of 20 cm and least on the wider plant spacing of 30 cm, which was observed in both years (Table 3)
Summary
Tepary bean (Phaseolus acutifolius) originally from the arid and semiarid environments of northwestern Mexico and the southwestern United States of America is an important legume crop [2, 3]. It possesses novel genes for abiotic and biotic stress tolerance useful in breeding its sister species common bean and other related species [4,5,6]. Planting pattern in tepary bean has been found to remarkably influence the yield of the crop in research conducted in semiarid Iran [16]. Intrarow spacing was reported to affect several yields and yieldrelated characters significantly such as lablab [17], cowpeas [18], soybean [19], and faba bean [20]
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