Estimating and Analyzing the Spatiotemporal Characteristics of Crop Yield Loss in Response to Drought in the Koshi River Basin, Nepal

The quantitative assessment of crop yield loss in response to drought is crucial in the development of the agricultural sector to improve the productivity. This study estimated and analyzed the spatiotemporal patterns of crop yield loss in response to drought using the Lagrange interpolation method, wavelet analysis, and sequential Mann-Kendall test in the mountain, hill, and Terai (low-land) regions of Nepal's Koshi River Basin from 1987 to 2016. According to the findings, average crop yield loss was common after 2000, with the Terai, hill, and mountain experiencing the greatest loss in maize, rice, and wheat, respectively. Average annual rice and wheat yield losses rate were highest in the mountains, while maize yield losses were highest in the Terai. There was an abrupt change in wheat yield loss in the mountain, with significant increasing trend. In the hill, significant increment in maize and wheat yield loss, and decrement in rice yield loss, were observed. Between 1987 and 2016, periodic variations of maize, rice, and wheat revealed significant yield loss after 2000. The characteristics of the first and second key periods for crop yield loss demonstrated variation period which predicted that crop yield loss would either enter high yield loss or low yield loss period shortly after 2016. The findings of the study provide a detailed intervention in assessing crop yield loss at the river basin level and can provide an important pathway for developing a crop yield loss mitigation plan in the agricultural sector to achieve self-reliance and sustainable agricultural productivity.

Remote Sensing Based Rapid Assessment of Flood Crop Damage Using Novel Disaster Vegetation Damage Index (DVDI)

Accurate crop-specific damage assessment immediately after flood events is crucial for grain pricing, food policy, and agricultural trade. The main goal of this research is to estimate the crop-specific damage that occurs immediately after flood events by using a newly developed Disaster Vegetation Damage Index (DVDI). By incorporating the DVDI along with information on crop types and flood inundation extents, this research assessed crop damage for three case-study events: Iowa Severe Storms and Flooding (DR 4386), Nebraska Severe Storms and Flooding (DR 4387), and Texas Severe Storms and Flooding (DR 4272). Crop damage is assessed on a qualitative scale and reported at the county level for the selected flood cases in Iowa, Nebraska, and Texas. More than half of flooded corn has experienced no damage, whereas 60% of affected soybean has a higher degree of loss in most of the selected counties in Iowa. Similarly, a total of 350 ha of soybean has moderate to severe damage whereas corn has a negligible impact in Cuming, which is the most affected county in Nebraska. A total of 454 ha of corn are severely damaged in Anderson County, Texas. More than 200 ha of alfalfa have moderate to severe damage in Navarro County, Texas. The results of damage assessment are validated through the NDVI profile and yield loss in percentage. A linear relation is found between DVDI values and crop yield loss. An R2 value of 0.54 indicates the potentiality of DVDI for rapid crop damage estimation. The results also indicate the association between DVDI class and crop yield loss.

Screening Twenty Cowpea (Vigna unguiculata (L.) Walp) Genotypes for Resistance to Thrips (Megalurothrips sjöstedti) in Burkina Faso

Losses caused by flower thrips in cowpea are important. These pests can cause from 60% to total crop yield loss. There is, therefore , an urgent need to address this issue. This work has been undertaken to identify sources of resistance to thrips in cowpea. Twenty cowpea genotypes were screened at Kamboinsé research station under improve netting in pots. The number of aborted flowers per line, the percentage of damage to flowers and stipules, and the number of thrips per genotype were evaluated. The results revealed the existence of six genotype of cowpea resistant to thrips. Among these genotypes three are already known thrips resistant lines (TVU1509, TVx3236 and Sanzi). Moreover, Sanzi showed interesting potentialities that maybe exploited. The new identified lines are Nafi, variety popularized in 2012 and variety KVx780-3 which is being popularized. The KVx165-14-1 (old popular variety) showed sources of tolerances while the KN1 genotype was susceptible to thrips. In another hand, all the wild genotypes showed high susceptibility to thrips.