Phenotypic and molecular characterization of a tomato (Solanum lycopersicum L.) F2 population segregation for improving shelf life.

Breeding for better quality fruits is a major focus for tomatoes, which are continuously subjected to post-harvest losses. Several methods have been used to improve the fruit shelf life of tomatoes, including the use of ripening gene mutants of Solanum lycopersicum. We developed extended shelf-life tomato hybrids with better quality fruits using ripening mutants. Nine tomato crosses were developed using 3 fruit ripening gene mutants of S. lycopersicum [alcobaca (alc), non-ripening, and ripening inhibitor] and 3 agronomically superior Indian cultivars ('Sankranti', 'Vaibhav', and 'Pusaruby') with short shelf life. The hybrid progenies developed from alc x 'Vaibhav' had the highest extended shelf life (up to 40 days) compared with that of other varieties and hybrids. Further, the F(2) progenies of alc x 'Vaibhav' were evaluated for fruit quality traits and yield parameters. A wide range of genetic variability was observed in shelf life (5-106 days) and fruit firmness (0.55-10.65 lbs/cm(2)). The potential polymorphic simple sequence repeat markers underlying shelf life traits were identified in an F(2) mapping population. The marker association with fruit quality traits and yield was confirmed with single-marker analysis and composite interval mapping. The genetic parameters analyzed in the parents and F(1) and F(2) populations indicated that the cross between the cultivar 'Vaibhav' and ripening gene mutant alc yielded fruit with long shelf life and good quality.

Management options for mid-century maize (Zea mays L.) in Ethiopia.

This simulation study was carried out to assess the impact of climate change and adaptation strategies on maize production across 22 locations in Ethiopia using Decision Support System for Agrotechnology Transfer - Cropping System Model (DSSAT-CSM) CERES-Maize. Three maize varieties, i.e., [BH-660 (late maturing), BH-540 (medium maturing) and Melkasa-1 (short maturing)] along with three planting dates [early (25-Apr), normal (25-May) and late (25-Jun)], four N fertilizer rates (64, 96, 128 and 160 kg N/ha) and three water levels [rainfed (no irrigation), two irrigations (each 30 mm at time of flowering and 5 d after flowering with total = 60 mm) and five irrigations (each 30 mm at time of flowering to early grain-filing, which were applied every five days in total = 150 mm)] were evaluated as the adaptation strategy. The mid-century (2040-2069) temperatures and solar radiation were extracted from multiple model means across the Coordinated Regional Climate Downscaling Experiment (CORDEX) models under the highest Representative Concentration Pathway (RCP8.5). Maize productivity was evaluated assuming that maize was grown on shallow sandy loam soils. Yield of an early, medium and late maturing maize were changed by -13 to -8%, -10 to +4% and + 3 to +13%, respectively, relative to the baseline period (1980-2005). The days to maturity decreased by about 16%. Under rainfed condition, N application up to 64, 128 and 160 kg/ha significantly improved yield for early, medium and late maturing varieties, respectively. Relatively high yield and low inter-seasonal yield variability were simulated for BH-660 and Melkasa-1 when planted on 25-Apr and 25-May, respectively, for most locations. Application of two (60 mm) and five (150 mm) irrigation levels improved yield in drier locations. In conclusion, this study provides potential adaptation options under the future climate in maize producing regions of Ethiopia.

Precipitation changes impact stream discharge, nitrate-nitrogen load more than agricultural management changes.

Nitrate-N losses to surface waters in the Upper Midwest of the Untied States have increased in recent decades, contributing to hypoxia in the Gulf of Mexico. This paper investigates whether increasing nitrate-N export from cropland in the Upper Midwest since the late 1960s results from changes in land use or climate. The Agricultural Drainage and Pesticide Transport (ADAPT) Model simulated current and historical agricultural systems under past and recent wet climate for Seven Mile Creek in Minnesota. Simulations were run with management and climate for three distinctly different periods--namely, 1965 to 1969, 1976 to 1980, and 1999 to 2003 (wettest period). Results showed discharge and nitrate-N losses responded more to changes in climate than management. The wetter period (1999-2003) caused a simulated 70% increase in discharge under 1960s-era management compared with that period's observed climate and a simulated 51% increase in discharge under 1970s-era management compared with the 1976 to 1980 climate. The recent, wetter climate also produced a 62% increase in nitrate-N losses for 1960s-era management compared with the actual climate and a 137% increase in nitrate-N losses for 1978 management conditions compared with actual 1970s climate. Had recent climate been in place and stable since 1965, agricultural changes would have decreased discharge by 6.4% through the late 1970s and then by another 21.1% under modern management but would have increased nitrate-N losses by 184% through the late 1970s and then decreased nitrate-N losses by 13.5% between 1978 and 2001. Management changes that were important drivers included increasing N-fertilizer rates, increases in corn acreage, and increases in crop yield. But the most important factor driving increased nitrate-N losses from agriculture since the 1970s was an increasingly wetter climate.

Spatial analysis of the impact of climate change factors and adaptation strategies on productivity of wheat in Ethiopia.

Wheat production is expected to be challenged by future climate change. However, it is unclear how wheat grown in diverse agroecologies will respond to climate change and adaptation management strategies. A geospatial simulation study was conducted to understand the impacts of climate change and adaptation management strategies on wheat (Triticum aestivum L.) production in Ethiopia. Simulation results showed that the average long-term baseline (1980-2005) wheat yield ranged from 1593 to 3356 kg/ha. This wheat yield range is within the national average (2100-2700 kg/ha) for this decade. In regions with cooler temperatures (<21 °C), mid-century temperatures and elevated CO2, along with increased N fertilizer slightly improved attainable yield levels above 3000 kg/ha. Whereas, in regions with heat and drought conditions wheat yield declined regardless the increase of N or CO2 levels. Wheat yield increased at a diminishing rate with increase in N fertilizer rate. However, N fertilizer did not increase yields under low rainfall conditions. Two to five irrigation per season contributed to yield improvement for low rainfall locations, while yield did not substantially improve for locations receiving adequate seasonal rainfall. Therefore, based on this study, improved N fertilizer application in combination with increased CO2 could improve wheat yield under future climate in most wheat producing regions (with adequate rainfall) of Ethiopia. Our results provide valuable information regarding impacts of climate change factors and adaptation strategies for producers, researchers, extension professionals and policy makers.

Water quality modeling of fertilizer management impacts on nitrate losses in tile drains at the field scale.

Nitrate losses from subsurface tile drained row cropland in the Upper Midwest U.S. contribute to hypoxia in the Gulf of Mexico. Strategies are needed to reduce nitrate losses to the Mississippi River. This paper evaluates the effect of fertilizer rate and timing on nitrate losses in two (East and West) commercial row crop fields located in south-central Minnesota. The Agricultural Drainage and Pesticide Transport (ADAPT) model was calibrated and validated for monthly subsurface tile drain flow and nitrate losses for a period of 1999-2003. Good agreement was found between observed and predicted tile drain flow and nitrate losses during the calibration period, with Nash-Sutcliffe modeling efficiencies of 0.75 and 0.56, respectively. Better agreements were observed for the validation period. The calibrated model was then used to evaluate the effects of rate and timing of fertilizer application on nitrate losses with a 50-yr climatic record (1954-2003). Significant reductions in nitrate losses were predicted by reducing fertilizer application rates and changing timing. A 13% reduction in nitrate losses was predicted when fall fertilizer application rate was reduced from 180 to 123 kg/ha. A further 9% reduction in nitrate losses can be achieved when switching from fall to spring application. Larger reductions in nitrate losses would require changes in fertilizer rate and timing, as well as other practices such as changing tile drain spacings and/or depths, fall cover cropping, or conversion of crop land to pasture.

A new stain for pollen fertility studies.

The juice from the berries of Cocculus hirsutum was extracted and used for pollen fertility studies in various crops. Two stains were prepared: P.H. Ramanjini (PHR) stain and modified PHR stain. The modified PHR stain contains lactic acid and produces the best staining differentiation. The intensity of the staining was dependent on the thickness of the pollen cell walls, hence PHR stain is recommended for thick walled pollen grains and the modified PHR stain for pollen with relatively thin walls. The preparation of both the stains are very simple, quick and inexpensive.