Defoliation timing for optimal leaf nutrition in dual‐use amaranth production systems

Abstract

BACKGROUND Amaranth leaves can provide important nutrients to small‐scale farming families growing amaranth for seed. Amaranth is known to be tolerant to defoliation, but there is little guidance on when defoliation should be performed for optimal nutritional benefits. This series of experiments assessed tolerance to defoliation at different points throughout the vegetative stage of development, in addition to the nutritional benefits and flavor of amaranth leaves at each stage. RESULTS Overall, timing of defoliation had no impact on seed yield or quality. Fifty percent defoliation at any point did not significantly reduce seed yield, whereas 100% defoliation throughout development reduced seed yield. The nutritional value of amaranth leaves differed substantially throughout development, with the highest concentrations of iron mid‐way through vegetative development, and the highest levels of vitamin A, magnesium, and copper at the end of the vegetative development stage. Palatability was highest in young leaves, and decreased as plants aged. We also found that neither timing nor intensity of defoliation had an influence on branching, which can negatively influence ease of harvest. CONCLUSIONS These results indicate that amaranth leaves are a nutritious food source that provides vital nutrients at different concentrations throughout development. Farmers who wish to harvest both leaves and seeds can harvest up to 50% of the leaves at any point during vegetative development or bud formation while maintaining seed yield. Leaf harvest timing can thus be tailored to nutritional needs, although palatability decreases with plant age. © 2020 Society of Chemical Industry

Highest Defoliation Tolerance in Amaranthus cruentus Plants at Panicle Development Is Associated With Sugar Starvation Responses

“…In common with most other plant stress conditions, defoliation in grain amaranth has been observed to negatively affect its energy reserve status ( Castrillón-Arbeláez et al, 2012 ; Vargas-Ortiz et al, 2013 ). Yet, contrary to other crops, defoliation may boost productivity if the stress is partial and performed at certain development stages ( Martínez-Moreno et al, 1999 ; Vargas-Ortiz et al, 2015 ; Hoidal et al, 2019 , 2020 ). Further evidence showed, however, that tolerance to severe mechanical defoliation in grain amaranth drastically drops at FL after reaching its apex at PE ( Vargas-Ortiz et al, 2015 ).…”

“…This and other amaranth species have been shown to be tolerant to defoliation. They also can compensate and even over-compensate in response to a large fraction of foliar tissue loss (i.e., 50-100%) and/or repeated defoliation events (Marquis, 1996;Martínez-Moreno et al, 1999;Castrillón-Arbeláez et al, 2012;Vargas-Ortiz et al, 2013;Hoidal et al, 2019Hoidal et al, , 2020. In A. cruentus, this capacity was related with rapid carbohydrate reallocation from root and stems after defoliation, which was accompanied by changes in sucrolytic and amylolytic gene expression and activity in these organs (Castrillón-Arbeláez et al, 2012;Vargas-Ortiz et al, 2013).…”

Exploring the potentials of underutilized grain amaranth (Amaranthusspp.) along the value chain for food and nutrition security: A review

“…It is a high yielding vegetable crop and a crop of great toast among rural and urban population in many communities (Chelang'a, Obare, and Kimenju 2013), Amaranth is a very versatile crop and has been called a multipurpose crop it resists drought, heat, pests and adapts more readily to new and harsh environments than conventional cereal crops. Its tolerance to a wide range of weather conditions and short production cycle present amaranth as possible "golden" vegetable of high economic importance (Hoidal et al 2020). As a home garden vegetable, it can be grown all year round.…”

Integrated Use of Cattle Manure and NPS Fertilizer to Improve the Yield of Grain Amaranth (Amaranthus caudatus L.) in Southwest Ethiopia

“…Some of its species are used as vital sources of food as both vegetable and grain and they are rich in calcium, potassium, phosphorus, iron, zinc, magnesium, and dietary ber [2][3][4]. It is also endowed with lysine-wealthy protein and a good supply of crucial amino acids [5][6][7]. Due to its dietary capability, amaranth may improve food as well as nutritional security in Ethiopia [8].…”