No abstract

Cassava (Manihot esculenta Crantz) is an important subsistence crop for many poor rural families in Africa. Cassava contains cyanogenic glucosides (linamarin and lotaustralin) which liberate hydrogen cyanide (HCN) during tuber processing. Once liberated, HCN attaches to the processed tuber. Continuous consumption of processed tuber containing high HCN concentration coupled with low protein intake causes Konzo-a paralyzing disorder that impacts children and women of childbearing age. There are ways to reduce HCN concentration during tuber processing; however, this can also reduce the overall starch content in the cassava tuber. A study comprising twenty treatments consisting of different combinations of nitrogen (N), phosphorus (P), and potassium (K) fertilizer rates was initiated in 2013 in the coastal Dondo District of Mozambique to assess cassava tuber quality as measured by starch and HCN. Significant differences were observed in starch content (CSC) of unprocessed tubers due to combined addition of N, P and K fertilizer rates, sample size, and estimation procedure. However, no significant differences were observed in HCN concentration in tubers due to the addition of N, P and K fertilizer. The HCN concentration in cassava tuber appears to be a function of the physiology of the crop or possibly cassava variety rather than the environment or conditions under which the crop is grown.

Cowpea (Vigna unguiculata (L.) Walp.) is an important legume crop with enormous nutritional, agronomic and economic value. Cowpea constitutes a large portion of the daily diet among many people in Africa, Asia, Central America, and Southern America. The United States was among the top 10 global producers of cowpea until 1967, when cowpea was grown primarily for soil management and livestock feed. With the projected increase in the minority population in the United States, from 25% in 1992 to 47% in 2050, it is expected that the consumption of cowpea in the nation will increase substantially. In this review, we provide information about cowpea production systems and prospects in the United States.

A population of Palmer amaranth (Amaranthus palmeri S. Watson) in Kansas (KSR) was found to have evolved resistance to three commonly used herbicides, i.e., chlorsulfuron, atrazine, and mesotrione. Our previous research confirmed the predominance of metabolic resistance to these herbicides in KSR, although a small percentage of plants also showed target-site alteration conferring resistance. In this research, we investigated the inheritance of resistance to these three herbicides in KSR Palmer amaranth. F1 and F2 progeny were generated by a conventional breeding approach. On the basis of the response of F1 and F2 progeny to three herbicide applications and χ2 analyses, we found that the resistance of KSR Palmer amaranth to chlorsulfuron and atrazine is controlled by single nuclear genes. However, resistance to mesotrione was found to be imparted by multiple nuclear alleles in this population. Single-gene resistance can spread rapidly, while multiple-gene traits are slower to evolve and spread. Regardless, adoption of integrated weed management strategies can minimize the spread of resistance.

Rapid growth of Palmer amaranth (Amaranthus palmeri S. Watson) poses a challenge for timely management of this weed. Dose response studies were conducted in 2017 and 2018 under field and greenhouse conditions near Garden City and Manhattan, KS, respectively, to evaluate the efficacy of dicamba to control ≤10 cm, 15 cm, and 30 cm tall-Palmer amaranth that mimics three herbicide application timing: on time application (Day 0), and 1 (Day 1) and 4 days (Day 4) delay. Visual injury rating and reduction in shoot biomass (% of non-treated), and mortality were assessed at four weeks after treatment using a three- and four-parameter log-logistic model, in R software program. Increasing dicamba doses increased A. palmeri control regardless of plant height both in the field and greenhouse studies. The results suggest that delaying application one (15 cm) and four days (30 cm), resulted in a two- and 27-fold increase in the effective dose of dicamba on A. palmeri, respectively, under field conditions. However, in the greenhouse, for the same level of A. palmeri control, more than one- and two-fold increase in dicamba dose, respectively was required. Similarly, the effective dose of dicamba required for 50% reduction in A. palmeri shoot biomass (GR50) increased more than four- and eight-fold or more than one- and two-fold when dicamba application was delayed by one (15 cm) and four days (30 cm), in the field or in the greenhouse, respectively. To understand the basis of increased efficacy of dicamba in controlling early growth stage of A. palmeri, dicamba absorption and translocation studies were conducted. Results indicate a significant reduction in dicamba absorption (7%) and translocation (15%) with increase in A. palmeri height. Therefore, increased absorption and translocation of dicamba results in increased efficacy in improving A. palmeri control at early growth stage.