Currently, maize (Zea mays L.) production is under threat from climate change, drought, and pests such as fall armyworm (FAW) [Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)]. Since its first detection outside of its native range in 2016, FAW has spread into 76 nations across Africa and Asia adversely affecting maize production and, in turn, the livelihoods of millions of smallholder farmers. Thus, there is a strong need for the development of cost-effective and biologically based integrated pest management (IPM) practices including host-plant resistance (HPR). However, most of the commercial maize cultivars have lost some defensive traits through selective breeding for yield during domestication. The majority of the commercially cultivated hybrids and cultivars in Asia and Africa are highly susceptible to FAW. Therefore, this review summarizes information about various maize landraces, native germplasm, and crop wild relatives (CWRs) possessing FAW resistance traits and about their potential resistance mechanisms, namely antibiosis, antixenosis, and tolerance. There is clear evidence of FAW resistance acting through diverse mechanisms in several maize landraces, germplasm lines, native populations, and CWRs such as Antigua race, FAW Tuxpeno, Zapalote Chico 2451F, Doce Flor da Serra, FAWCC (C5), CMS 14C, PopG (C2), MpSWCB-4, Mp708, Mp 704, CML 67, and FAW 7050, as well as a few species of teosinte and Tripsacum L. Further, a scheme that outlines strategies and approaches for prebreeding and their introgression into elite cultivars for developing FAW-resistant maize is proposed as a possible way forward.
Tag: global warming
Reduction of global warming potential vis-à-vis greenhouse gases through traditional agroforestry systems in Rajasthan, India
Tree-based systems in arid region of India are an integral part of livelihood and environment security. Traditionally, the maintenance of scattered trees on farm to reap several tangible and intangible benefits is a way of life. Presently, these systems are often known as low-hanging fruit and become a key weapon to fight climate change evil by offsetting greenhouse gas (GHG) emission through carbon sequestration. Therefore, to quantify the offsetting potential of GHG emission and area occupied by these tree-based systems in Rajasthan was undertaken. The study was carried out into two major aspects: estimation of agroforestry area using satellite remote sensing data, and to estimate the carbon sequestration potential of existing agroforestry by using dynamic CO2FIXv3.1 model for a simulation period of 30-years in five districts (20% sampling), namely, Bikaner, Dausa, Jhunjhunu, Pali and Sikar from Rajasthan, India. The estimated area under agroforestry in Rajasthan was 1.49 million ha. The findings revealed that the major tree species existing on farmer’s field were Prosopis cineraria, Tecomella undulata, Capparis decidua, Acacia tortilis, Prosopis juliflora, Azadirachta indica and Ziziphus mauritiana with an observed number of trees in selected districts varied from 1.40 to 14.90 ha−1(with average tree density of 9.71 ha−1). The total biomass (tree + Crop) varied from 2.22 to 19.19 Mg ha−1, whereas the total biomass carbon ranged from 1.00 to 8.64 Mg C ha−1. The soil organic carbon ranged from 4.51 to 16.50 Mg C ha−1. The average estimated carbon sequestration and mitigation potential of the agroforestry were 0.26 Mg C ha−1 year−1and 0.95 Mg CO2 eq ha−1 year−1 on farmers’ field of Rajasthan. At the state level, the reduction of GHG emission potential of agroforestry was found to be 1.42 million tonnes annually, which helps to cut carbon footprint and achieve targets of Paris agreement.
Population dynamics of Hippophae rhamnoides shrub in response of sea-level rise and insect outbreaks
The coastal vegetation of islands is expected to be affected by future sea-level rise and other anthropogenic impacts. The biodiverse coastal vegetation on the eastern part of the Dutch Wadden Island of Ameland has experienced land subsidence caused by gas extraction since 1986. This subsidence mimics future sea-level rising through increased flooding and raising groundwater levels. We studied the effects of this relative sea-level rise and other environmental factors (i.e. insect outbreaks, temperature and precipitation) on the population dynamics (i.e. cover and age structure and annual growth) of the shrub seabuckthorn (Hippophae rhamnoides L.) in young (formed after 1950) and old (formed before 1950) dune areas over a period of 56 years (1959–2015). We found an increase in seabuckthorn cover in the young dune areas since 1959, while over time the population in the old dunes decreased due to successional replacement by other species. With the increasing age of the young dunes, we found also a decrease in sea-buckthorn after 2009. However the sharp decrease indicated that other environmental factors were also involved. The most important determinant of annual shrub growth appeared to be five outbreaks of the brown-tail moth (Euproctis chrysorrhoea L.), in the last decade. Relative sea-level rise caused more frequent flooding and reduced growth at lower elevations due to inundation or soil water saturation. This study clearly indicates that sea-buckthorn is affected by relative sea-level rise, but that other ecological events better explain its variation in growth. Although shrub distribution and growth can be monitored with robust methods, future predictions of vegetation dynamics are complicated by unpredictable extreme events caused by (a)biotic stressors such as insect outbreaks.