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Feedstock genetics and environment are important factors determining biomass yield of biofuel crops. Field studies were conducted to evaluate agronomic performance of four energy cane (Saccharum spp. hybrid) genotypes (TUS11-62, TUS11-58, TCP10-4928, and Ho 02-113) in the Texas Rolling Plains. In the first study, cane billets were planted in 2015 and data were collected from first (2016) and second (2017) ratoons. A second study was planted in 2016 and data were collected the same year from plant cane. Data collected include biomass, stalk height, stalk population, leaf area index (LAI), and normalized difference vegetation index (NDVI). Biomass yield of ratoons was not significantly different (p > .05) among genotypes. However, TUS11-58 had the highest plant cane yield. The average biomass yield of plant cane, first, and second ratoons were 20.2, 40.4, and 26.4 t ha −1 respectively. Longer growing period of ratoon (∼8 mo) compared to plant cane (∼5.5 mo) increased biomass. However, low temperatures (−14 to −16 • C) during the dormant phase resulted in lower yield of the second ratoon. Among genotypes, TUS11-62 had taller stalks, but was cold sensitive. Genotype TCP10-4928 had higher stalk population and LAI. An exponential relationship was observed between LAI and NDVI (R 2 = .67). Overall, there were differences in growth characteristics of energy cane genotypes, however biomass yield was similar in the ratoon phase. The results of this study showed that low temperature tolerance and growing season duration are key factors in determining biomass yield in higher latitude regions such as the Texas Rolling Plains.

Capsicum (Solanaceae), comprising of sweet and hot chilli pepper, is a globally known spice crop. This genus is well known for its huge genetic diversity at intra- and inter-species level. Diversity among Akabarechilli landraces, a unique Capsicum from Nepal, has not been studied so far. The present study characterized thirty accessions of Akabarechilli using 26 qualitative and 21 quantitative agro-morphological markers at the experimental plots of National Genebank, Khumaltar, Nepal during the summer season of 2018/019. Using principal component analysis, the first- principal components with eigen-values more than 1 contributed 25% of the variability among accessions for quantitative traits, whereas the first principal components with eigen-values more than 1 contributed 22.2% of the variability among accessions for qualitative traits. These findings suggested a wide range of morphological variations among the tested accessions. Based on qualitative and quantitative traits, 30 accessions were grouped into 6 distinct clusters by Euclidian distance and average method. Accessions CO-11048 and CO-11050 under cluster-III were round shape fruit type and accessions CO-11044, CO- 11046 andCO-11047 under cluster-I were high fruiting with longer fruitbearing period and could be utilized for breeding purpose as these are the traits preferred by consumers or processors in Nepalese market. SAARC J. Agric., 19(2): 37-55 (2021)

Thermal imaging has been used to determine canopy temperature and study plant water relationships. The objective of this study was to investigate the potential use of infrared thermal imaging to determine crop canopy temperature (Tc) and evaluate wheat (Triticum aestivum L.) genotypes under drought conditions. Thermal images were acquired at anthesis and grain-filling stages from 17 genotypes grown under dryland conditions in 2015 and 2016 winter wheat growing season at Bushland, TX. A handheld thermal camera was used to acquire thermal images and the images were processed using customized image processing software. The customized software filters out the background soil from the thermal images and calculates the mean Tc.A significant difference (p < .05) in Tc among genotypes was found during grain filling in 2015 and at anthesis in 2016. Genotypes TAM 111, TAM 114, PlainsGold Byrd, and Jagalene had cooler canopies, and Billings, TAM 304, and TAM 105 had warmer canopies in both years. There was a significant negative correlation between grain yield and Tc measured at anthesis (r =-.48, p < .05) and grain-filling (r = -.33, p < .05). Infrared thermal imaging showed a promising method to obtain Tc, which can be used to evaluate genotypes for drought tolerance.

The Decision Support System for Agrotechnology Transfer for sugarcane (DSSAT-CANEGRO) was evaluated for simulating the growth of energy cane (Saccharum spp. hybrid), a perennial biofuel feedstock crop. Plant growth data collected from a field experiment conducted in the semi-arid Texas Rolling Plains was used for model calibration and validation. All model performance indicators showed good agreement between simulated and measured biomass accumulation. After calibration, model was used for simulating plant cane and ratoon biomass yield using long-term (i.e., 33-year) historic weather data under rainfed and two irrigation levels. The irrigated treatments were a) 300 mm seasonal supplementary irrigation and b) auto-irrigation to replenish soil water in the profile to field capacity. The long-term average biomass yield of plant cane (6.4 ± 0.47 Mg ha -1 ) and ratoon (14.4 ± 0.92 Mg ha -1 ) were the lowest when simulated under rainfed conditions. Supplemental irrigation with 300 mm irrigation water significantly increased yield of both crops (14.6 ± 0.53 Mg ha -1 for plant cane and 29.5 ± 1.33 Mg ha -1 for ratoon). The auto-irrigation option substantially increased the amount of water applied and resulted in an average biomass of 16.7 ± 0.24 Mg ha -1 for plant cane and 44.4 ± 0.36 Mg ha -1 for ratoon.Biomass water use efficiency was the highest for ratoon due to its longer growing season. This modeling study showed reasonable performance of DSSAT-CANEGRO for simulating energy cane growth. Irrigation experiments using historical data showed energy cane as a competitive biomass crop in the Texas Rolling Plains region. INTRODUCTIONCrop simulation models are widely used in many aspects of crop improvement due to their ability to integrate the response of genotype, environment, management practices, and their Abbreviations: CANEGRO, sugarcane crop simulation model included in the DSSAT software; CRM, coefficient of residual mass; DSSAT, Decision Support System for Agrotechnology Transfer; ET, evapotranspiration; LAI, leaf area index; MAE, mean absolute error; RMSE, root mean square error; WUE, water use efficiency; WUE B , biomass water use efficiency.