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In sugarcane, flowering is required for breeding but undesirable in commercial crops because it reduces yield and quality which is exacerbated by the development of side shoots and pithing in stalks. The objectives of this study were to determine the effect of location on genotype flowering, estimate broad sense heritability and evaluate flowering trends among irrigated cultivars. Total number of flowered stalks per plot were counted from trials at Pongola research station (PRS), Mpumalanga research station (MRS) and Delmont farm (DF) and converted to flowers per hectare (FPH). There was significant location effect with higher flowers at PRS compared to MRS and DF. Significant genotype by location (GL) indicated location influenced on genotype flowering. Significant genotype and GL variances indicated genetic variability for flowering and effect of location on genetic variability. The high broad sense heritability (0.70–0.97) suggested selecting low flowering genotypes will be efficient. Cultivars such as N71 and N73 (no flowering) would be suitable for late season, while N36 (63,000 FPH), N53 (63,000 FPH) and N70 (68,000 FPH) must be harvested early to mid-season where effects of flowering are low. Significant genetic variability and high broad sense heritability indicated breeding for low flowering will be efficient.

In Mississippi, rice reproduction and ripening often overlaps with soybean maturation, creating potential for herbicide exposure onto rice from desiccants applied to soybeans. Six independent studies were conducted concurrently at the Delta Research and Extension Center in Stoneville, MS, from 2016 to 2018 to determine the response of rice to sublethal concentrations of soybean desiccants during rice reproductive and ripening growth stages. Studies included the desiccants paraquat, glyphosate, saflufenacil, sodium chlorate, paraquat + saflufenacil, and paraquat + sodium chlorate applied at a rate equal to 1/10th of Mississippi recommendations. Treatments were applied at five different rice growth stages, beginning at 50% heading––defined as 0 d after heading (DAH)––with subsequent applications at 1-wk intervals (0, 7, 14, 21, and 28 DAH), up to harvest. Injury was observed 7 d after application (DAA), with five of six desiccants at all application timings. No injury was observed with glyphosate application across all rating intervals. Rough rice grain yield following all glyphosate applications was reduced by >6%. In the studies evaluating paraquat, injury ranged from 5% to 18% at all evaluations, regardless of application timing. Rough rice grain yield was reduced >12% 0 to 21 DAH, following paraquat application. Similar trends were observed with paraquat + saflufenacil and paraquat + sodium chlorate, with rice exhibiting yield decreases >6% following an application 0 to 14 and 0 to 21 DAH, respectively. In studies evaluating saflufenacil and sodium chlorate, rough rice grain yield was >95% of the untreated across all application timings Yield component trends closely resembled reductions observed in rough rice grain yield. Reductions in head rice yield were >5% following applications of paraquat or paraquat + saflufenacil 0 to 14 and 0 to 21 DAH, respectively. Late-season exposure to sublethal concentrations of desiccant from 50% heading (0 DAH) to 28 DAH has an impact on rough rice grain yield, yield components, and head rice yield.

In this study, photosynthesis and assimilate translocation and their contribution to improving grain yield and harvest index (HI) of triticale under different N sources and irrigation regimes in an...

On-site surveys of weed populations provide information on the relative occurrence and density of weeds that can be useful to growers in that region. Data generated by weed surveys can aid in the management of weed issues by monitoring the movement of problem weeds and forecasting areas susceptible to infestations. Currently, on-site surveys are often performed on a small scale, within single fields or counties. Questionnaire surveys are helpful for assessing relative abundance but do not always provide detailed information on weed distribution in time or space. A survey was conducted annually in Ohio from 2013 through 2017 in 49 counties with soybean [Glycine max (L.) Merr.] production to assess the late-season occurrence of horseweed [Conyza canadensis (L.) Cronquist]. The objectives of this research were to: (1) determine the frequency, level of infestation, and distribution of C. canadensis in soybean fields in the primary soybean-producing Ohio counties over 5 yr; and (2) identify significant spatial clusters or movement trends over time. Conyza canadensis was encountered in each county from 2013 through 2017. Spatial cores of interest, or counties identified as having significant levels of C. canadensis infestations or a lack thereof relative to surrounding counties, were identified in all years except 2017. The lowest frequency of C. canadensis encountered at all rating levels occurred in 2017, which coincided with second-highest frequency of infestations (highest density level) among years. There was no distinct distribution or pattern of C. canadensis movement within the state from year to year, but there was an increase in counties with infestations over time compared with the early years of the survey when many counties had few to no infestations. These results suggest that C. canadensis persists as a common and troublesome threat to Ohio soybean producers and that growers should continue making C. canadensis management a priority when developing weed control programs.

New indica and japonica hybrid rice cultivars, such as the Yongyou series, provide farmers with very high yield potential. However, information on their canopy light capture and solar radiation use efficiency in the late season is limited. Field experiments were performed to compare the radiation-use parameters of four rice types: indica rice (IR), inbred japonica rice (IJR), hybrid japonica rice (HJR), and hybrid indica/japonica rice (HIJR), from 2016 to 2018 during the late season in Hangzhou, China. The grain yield, aboveground biomass, intercepted solar radiation (SI), and radiation-use efficiency (RUE) of the HIJR were on average respectively 13.4%–53.4%, 14.3%–30.6%, 7.6%–21.4%, and 8.2%–14.9% higher than those of the HJR, IJR, and IR. The leaf area index (LAI) of the HIJR was 18.2%–57.0% greater than that of the IJR and HJR at four growth stages, resulting in respectively 17.8%–38.5% and 10.7%–42.8% greater canopy light interception rates (LIR) and amount of intercepted solar radiation during the vegetative stage. The prolonged grain-filling stage also led to respectively 33.9%–52.6% and 30.5%–51.4% increases in amounts of incident and intercepted radiation for the HIJR relative to the IR during grain filling. These results indicate that the SI superiority of the HIJR was caused by canopy closure as rapid as that of the IR during the vegetative stage (greater LAI and canopy LIR during the growing season) and a grain-filling stage as long as that of the HJR. For grain-filling stage, differences in leaf Pn between HIJR, IR, and IJR were not significant, suggesting that the greater RUE of the HIJR (12.7%–52.8% higher) than that of the other rice types resulted from improved canopy architecture after flowering (FL). Principal components analysis (PCA) revealed that the superiority of the HIJR in terms of solar radiation use resulted from the greater canopy light capture capability of IR and the prolonged growth period (especially during grain filling) of japonica rice in the late growing season.

Studying weed spatial distribution patterns and implementing precise herbicide applications requires accurate weed mapping. In this study, a simple unmanned aerial vehicle (UAV) was utilized to survey 11 dry onion (Allium cepa L.) commercial fields to examine late-season weed classification and investigate weeds spatial pattern. In addition, orthomosaics were resampled to a coarser spatial resolution to simulate and examine the accuracy of weed mapping at different altitudes. Overall, 176 weed maps were generated and evaluated. Pixel and object-based image analyses were assessed, employing two supervised classification algorithms: Maximum Likelihood (ML) and Support Vector Machine (SVM). Classification processes resulted in highly accurate weed maps across all spatial resolutions tested. Weed maps contributed to three insights regarding the late-season weed spatial pattern in onion fields: 1) weed coverage varied significantly between fields, ranging from 1 to 79%; 2) weed coverage was similar within and between crop rows; and 3) weed pattern was patchy in all fields. The last finding, combined with the ability to map weeds using a low cost, off-the-shelf UAV, constitutes an important step in developing precise weed control management in onion fields.

Brazil is the largest sugarcane producing country in the world. Mills usually operate nine months to process the sugarcane produced in the country. Here we investigated the effect of harvest time on the on-farm sugarcane yield and yield components (stalk fresh yield [SFY], sucrose yield [SY], and sucrose concentration [POL%]). We used a large database collected from commercial sugarcane blocks to assess the effect of harvest time on SY and yield components. Blocks were first clustered based on similarity of climate and soil, referred as environments, and the effect of harvest season on SY, SFY, and POL%, as influenced by the environment and the number of harvests, was evaluated using analysis of variance. Harvest season strongly influenced POL% and SY but had a comparably smaller effect on SFY. Although relatively smaller compared with other sources of variation, there was a statistically significant interactive effect of harvest number and harvest season on SY, with highest SY when harvest occurred during the mid-season or late season in old ratoons and during the mid-season in the case of young ratoons. Closing the yield gap due to sub-optimal harvest time by concentrating the harvest around the productivity peak would increase national sucrose production by 8%, but this is not possible due to logistic and milling constrains. In contrast, our findings suggested room to extend the harvest period to 10 months, which will free up milling capacity by 8% with no yield penalty. The extra milling capacity could serve as a motivation to increase productivity via agronomic practices to fully exploit the milling processing capacity.

Highlights Changes in yield, losses, and quality due to delayed harvest were evaluated. No significant changes in potential yield were observed over three years. Observed yield decreased late season with lodging present. Losses at the combine head represented largest fraction of measured loss. Abstract . Potential changes in yield and harvest losses that can occur while field drying corn are key considerations when evaluating harvest timing and energy costs associated with artificial drying. This study presents a three-year evaluation of corn harvest in Kentucky. Potential yield, observed yield, measured losses, and quality changes were monitored in a single field at multiple points over the harvest season to assess changes with respect to time and moisture. Measured losses were typically less than 1% of the potential yield in a good standing crop, consistent with results from cooperator combines (0.8% to 2.4%). When lodging was present, variability increased, and measured losses increased to between 5.3% and 9.1% of the potential yield, primarily as a result of ears missed by the combine head. No significant changes in potential yield were found, indicating potential yield was stable over the period examined. In two of the three seasons evaluated, extended delays resulted in an increase in lodging, and the observed yield was significantly reduced by up to 42.5%. Allowing the grain to field dry generally improved test weight; however, there was a trend of increased mold and other damage with prolonged field drying in one season. Keywords: Combines, Grain quality, Harvest loss, Maize, Preharvest loss.

An experiment was carried out to assess the nutritional value along with quality of curds in late season cauliflower varieties at Rampur, Chitwan during November 2017 to March, 2018. The eleven late season cauliflower varieties were Freedom, Titan, Ravella, Amazing, Artica, Bishop, Casper, Indam 9803, NS 106, Snow Mystique and Snowball 16 which were introduced from USA, Europe, India and Nepal. The experiment was prepared in a Randomized Complete Block Design (RCBD) with four replications. The main objective of this study was to check the nutritional content, taste, compactness, appearance and freshness of the curds in eleven late season cauliflower varieties at Rampur, Chitwan. Nutritional value along with taste quality, compactness, appearance and freshness of the curds were measured after harvest. Maximum moisture and carbohydrate content was found in Freedom while higher crude fat was obtained in Titan and Bishop. Similarly, higher crude protein and crude fiber was found in NS 106. Significantly better taste score (8.8) was found in Snowball 16 than other varieties. Better compactness score of curd was found in Artica and Titan than other varieties. Significantly better appearance score (8.0) was found in Artica but poor appearance score was found in Casper than other varieties. At different intervals after harvesting of curds, significantly fresher curds were found in Artica than other varieties. In conclusion, NS 106 performed higher content of crude protein and crude fiber while Snowball 16 executed better tasty curds than other varieties. Artica also showed better performance on freshness of curds than other varieties. Int. J. Appl. Sci. Biotechnol. Vol 8(4): 427-431

The experiment was conducted at Horticulture Farm of Agriculture and Forestry University, Rampur, Nepal during the November 2016 to March 2018 for two consecutive years to assess the characteristics on postharvest quality of late season cauliflower varieties. The experiment was laid in a Randomized Complete Block Design (RCBD) with the eleven late season cauliflower varieties viz., Freedom, Titan, Ravella, Amazing, Artica, Bishop, Casper, Indam 9803, NS 106, Snow Mystique, and Snowball 16, each replicated with four times. Significantly higher TSS value of 5.7º Brix was produced by Snowball 16 than other varieties. Considerably higher vitamin C of 49 mg/100 g was found in Amazing than other varieties. Significantly lower physiological loss in weight of 5.3%, 9.6% and 15.6% was found in Artica at three, six and nine days after harvesting, respectively. Higher score for the taste of curd was 8.8 in Snowball 16 followed by Amazing while lower score for taste of the curd was 4.8 in Indam 9803 variety. The attractive color and more compact curd score of 8.4 was found in both Titan and Artica than other varieties. Therefore, it can be concluded that Snowball 16 and Amazing varieties were the best open pollinated varieties for taste of the curd and composition of chemical constitutes. Bishop, Snow Mystique, NS 106, Artica and Titan varieties were other probable hybrid varieties based on their overall postharvest characteristics.

Climate change affects maize production in the east of Northwest China (ENC). Based on the meteorological data, maize growth phase data, and yield data in the ENC, spatial clustering and mixed linear models were used to evaluate the effects of climatic factors and drought on maize yield. The results showed that under the background of climate change, the sowing time was earlier, the maize development phase was shorter, the mid-season was longer, and whole growth duration increased, and the planting boundary moved further northward and expanded westward. In the whole growth duration, the temperature increased and the effective precipitation (Peff) decreased. Drought increased in the initial and late season of maize growth. Maize yield was selected as an attribute element for spatial clustering, and the ENC was divided into high–high cluster (HH), low–low cluster (LL), and high–low outlier (HL) areas. In the HH area, in any growth stage, the Peff reduction and drought stress reduced the maize yield; in the initial phase, increased temperature and decreased radiation increased maize yield; in the mid-season phase, increased temperature reduced maize yield. In the LL area, increased temperature in the initial and late season phases and the decreased temperature in the development phase were conducive to the formation of maize yield; the increase of Peff in the mid-season phase and its decrease in the late season phases increased maize yield; drought mainly affected the maize development phase. In the HL area, increased temperature in the development phase and decreased temperature in the mid-season phase increased maize yield; the Peff had a positive effect on the yield, mainly affecting the development and late season phases of maize; drought stress mainly affected the initial, development, and mid-season phases of maize. These new scientific discoveries are significant for maize production management in the ENC.

Cauliflower is an important winter season vegetable crop having year-round demand in Nepal. Due to longer crop duration in late winter season, there was a production of poor-quality curds and lower yield faced by the farmers in Terai region of Nepal. An experiment was conducted to identify the short duration late season varieties at Rampur, Chitwan Nepal during November 2016 to March, 2017. These varieties were Freedom, Titan, Ravella, Amazing, Artica, Bishop, Casper, Indam 9803 and NS 106 (introduced from USA, Europe and India), and Snow Mystique and Snowball 16 (introduced from Japan). The experiment was laid out in Randomized Complete Block Design (RCBD) with four replications. The highest plant height (71.9 cm) and canopy diameter (74.5 cm) at last harvest of cauliflower was mostly produced by Titan followed by NS 106, Snow Mystique, Bishop and Indam 9803. Similarly, significantly shorter period for final curd initiation of 65 days after transplanting was observed in Freedom and shorter period for final curd maturation of 77 days after transplanting was also recorded in Freedom than other varieties. Significantly, higher curd yield of 54.8 t/ha was produced by Bishop than other varieties. In conclusion, Bishop was the best hybrid variety while other suitable varieties were NS 106, Titan, Artica and Snow Mystique for better growth and higher curd yield in Chitwan condition. Similarly, Freedom was identified as short duration varieties which can minimize the negative effects in late winter season due to higher temperature.

In tomato production, the accruing green biomass shows promising potential as source of health-promoting compounds, such as rutin and solanesol, that are of high interest due to their medicinal properties. Naturally, they accumulate in plants growing in suboptimal growing conditions, e.g. influenced by biotic and abiotic stressors. With the aim to evaluate the potential use of tomato residues as source, we analyzed both leaf metabolites during a complete cultivation cycle, while applying single and combined stresses practically realized in greenhouse production. In the late season, contents of both metabolites were significantly enhanced by nutrient deficit in combination with 2 °C colder nights for 4 weeks and prolonged for in total 9 weeks. Particularly, higher solanesol contents were achieved by salt stress and elevated temperature after one week, even stronger when combined with drought. At harvest, stressed plants consist of less green biomass reducing the overall economic potential. However, practicable abiotic stresses should be considered as potential tool to induce the accumulation of beneficial compounds. Extracting profitable metabolites from the green biomass of the model crop tomato supports the overall goal to promote sustainable approaches in horticultural production.

Maize, an important staple crop is emerging as cash crop particularly for smallholder farmers in Nigeria. This paper evaluates the frequency of maize streak disease on maize sown during late cropping season in three agricultural zones of Benue State, with three maize cultivars; Super 98, Obasuper 1 and a local cultivar at the University of Agriculture Makurdi Research Farm using standard methods. Maize plots were sampled for streak disease from July to November. Data were analysed using descriptive statistics and ANOVA with means separated using FLSD(p=0.05). Spread of maize streak was low (< 20.0%) across the agricultural zones. It was, however, significantly different (p≤0.05) among the zones with 17.2% average, although reached 19.2 % at Zone B in one occasion. Streak severity was equally significant (p≤0.05) but high (3.6%) across zones, reaching its peak, 3.7 at Zone C while zone B (3.4) was least. Disease spread among the LGAs in the State equally differed significantly (p

Feld experiments were conducted at four locations of Bangladesh (Manikgonj, Cumilla, Dinajpur and Joshore) to optimize sowing date for higher seed yield of jute in late sown condition. The experimental variables constituted with three genotypes (O-72, O-3820 and Acc.4311) and three sowing dates (31 July, 15 August and 30 August).Each experiment was laid out in a randomized complete block design with three replications. The treatment combinations were assigned randomly and afresh randomization was followed in each replication. Results showed that the genotype Acc.4311, O-72 and O- 3820 produced maximum number of branches (5.40, 4.90 and 4.40, respectively) plant-1 on 15 August sowing at Manikgonj. The genotype Acc.4311 produced higher number of pods plant-1 than other two genotypes (O-72 and O-3820) in all sowing dates andat all the locations. The highest number of seedspod-1 (220.80) was found from the genotype Acc.4311grown at Manikgonj which was statistically similar (196.90) with that of the same genotype sown on the same date at Joshore. The highest thousand seed weight (2.478 g) was recorded from the seeds of genotype Acc.4311 sown on 15 August at Manikgonj followed by same genotype at Joshore.Finally, the genotype Acc.4311 sown on 15 August produced the highest seed yield (2.478 t ha-1) at Manikgonjwhich was significantly higher than those of sown on 31 July and 30 August at the same location. As the genotype Acc.4311 was found outstanding sown on 15 August over locations, this genotype may be considered promising for higher seed yield of olitorius jute in late season. Bangladesh Agron. J. 2019, 22(2): 83-89

In temperate climatic regions where severe winter conditions persist, the winter hardiness and fruit yield of strawberry cultivars vary greatly in perennial production systems. A 4-year study was c...

Agricultural productivity per unit of land is a global concern. Moreover, farmers seek to add value to their enterprises. Interest has increased in harvesting Valencia market type peanut (Arachis hypogaea L. subsp. fastigiata var. fastigiata) for forage in food production systems. Trials at two sites near Brownfield, TX, USA, in 2012 and 2013, evaluated forage harvest timing [18, 20, 21, and 22 weeks after planting, (WAP), the last of which was sun-cured in the field from digging until threshing] on forage yield and nutritive value and pod yield of Valencia market type. Producers can harvest hay with greater nutritive value than stover by cutting and baling earlier during the pod maturation phase (about 18 WAP) although pod yield would be significantly (P < 0.05) reduced (2280, 2470, 2880, and 3450 kg pods/ha when forage was harvested 18, 20, 21, and 22 WAP, respectively, SEM = 90). Additionally, forage organic matter (OM) yield declined with each harvest after 18 WAP (3450, 2900, 2670, and 2460 kg OM/ha for forage harvested 18, 20, 21, and 22 WAP, respectively, SEM = 70). Crude protein (CP) concentration decreased across harvest dates from 158 to 124 g/kg and fiber fractions increased. Forage harvest prior to digging is not a viable option to add value to Valencia market type production because of reduced pod yield, which is the more valuable component. Other studies using different market types in other environments with earlier and similar harvest timings yielded similar results.

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is an important pest of cotton in many areas of the southern United States. An experiment was conducted at two locations in Mississippi during 2016 and 2017 to evaluate action thresholds for tarnished plant bug on a novel Bacillus thuringiensis cotton that expresses the Cry51Aa2.834_16 toxin. Treatments included the current action threshold, a 2× threshold, and treatments where insecticides were only applied during the early season (preflower) or only during late season (during flowering) based on the current action thresholds. These were compared to an untreated control and a weekly insecticide use regime that received weekly insecticide sprays. All treatments were imposed on both Bt Cry1Aa2.834_16 cotton and a nontraited cotton. The Bt Cry1Aa2.834_16 trait reduced the number of tarnished plant bugs and injury, and improved yields compared to nontraited cotton. For all spray treatments except the weekly insecticide use regime, yields were greater for the Bt Cry51Aa2.834_16 cotton than the nontraited cotton. In terms of thresholds, Bt Cry1Aa2.834_16 cotton sprayed based on current action thresholds resulted in similar yields to the weekly insecticide use regime of both cotton types. In contrast, the 2× threshold resulted in lower yields than the current threshold for both cotton types. Though thresholds intermediate to the currently recommended action threshold and the 2× threshold were not tested, these data suggest that currently recommended action thresholds appear appropriate for Bt Cry51Aa2.834_16 cotton. These results suggest that this trait will be an important component of current IPM programs in cotton where tarnished plant bug is an important pest.

Populations of the brown stink bug, Euschistus servus (Say), in Florida peach orchards were monitored during the 2017 and 2018 growing seasons using yellow pheromone-baited pyramid traps. Peaches were evaluated at harvest for the presence of stink bug injury. A relationship between E. servus trap capture and fruit injury was used to estimate the economic injury level (EIL) for varying scenarios of crop price, per-hectare yield, and control costs. Economic thresholds were then set based on observed E. servus population trends and expected rates of increase. Thresholds were lowest in the period immediately following shuck split due to the rapid increase in E. servus populations during this period. Euschistus servus trap capture trended downward at the time of harvest. Therefore, increased E. servus management early in the Florida peach season provides the greatest overall benefit, whereas late season populations decline independent of management actions. The proposed EIL for Florida peaches determined by this study is 5.53 E. servus per trap over a 14-d trapping period, which was surpassed in only 16 of the 60 recorded trapping periods. This suggests that the current recommended spray frequency may not be economically justified.

Dried fig industry is the most affected from MeBr ban due to prevalence of storage pests namely fig moth, Ephestia cautella Walk. Magnesium phosphide was tested for exposure times of 5 and 7 days at 1.0 and 2.0 g t-1 phosphine (PH3) of dried fig under tarpaulin to control two major pests of dried figs, fig moth (Ephestia cautella Walk.) and fig mite (Carpoglyphus lactis L.). The experiment was performed to test the efficiency of phosphine treatment during a cooler period. The control fruits were fumigated with MeBr at 60 g m-3 level for 24 h. The results proved that the tested concentrations and exposure periods to PH3 provided 100% mortality of the test species. After exposure to PH3 or MeBr, fruit quality was preserved under ambient storage conditions for three months. A minimum of 5 days exposure after PH3 applied as 1-2 g per ton of dried fig is required during cooler period. © 2020 International Society for Horticultural Science. All rights reserved., TTGV-P2/30m World Bank Group, WBG, The experiment is a part of the multi-year project “Project to Phase-out Methyl Bromide in the Dried Fig Sector in Turkey (TTGV-P2/30m)” funded by the World Bank through the

In order to reduce the damage caused by the late-season drought stress of canola, a factorial split-plot experiment was performed based on the randomized complete blocks design with three replicati...

A survey on the incidence of onion yellow dwarf virus (OYDV) and iris yellow spot virus (IYSV) was carried out over three production cycles of onion ‘Rossa di Tropea’ in Calabria, Italy. OYDV was found to be the prevalent virus. ‘Rossa di Tropea’ seedbeds adjacent to OYDV-infected green onion field had seedlings with 1.76% infection rate determining 36.2% and 98.67% infected plants in the bulbs and in the subsequent seed harvesting times, respectively. When seedbeds were at least one km away from other onion crops seedlings and bulb cultivation had the infection rate close to zero. OYDV was detected in whole plants except the roots and outer desiccated bulb skins. Seed transmission was not detected in ‘Rossa di Tropea’. Early OYDV infection significantly reduced the number and weight of seeds/inflorescence compared to late season infection, while the weight of 100 seeds was not different in the two early and late OYDV infected plants. IYSV was never found in seedbeds. It was always detected first in seed crops (April) than in bulb crops (June), and the final infection rate was higher in seed (2.67%–3.33%) than in bulb crops (0%–0.87%), suggesting there was an internal source of viral inoculum in the field. IYSV was detected in 3/123 apex bulbs randomly collected from stored bulbs and in 12/12 apex fresh bulbs collected at harvest time from infected plants, suggesting the role of bulbs as IYSV inoculum source. On the contrary, randomly collected bulbs (N = 109) from warehouse and bulbs of infected plants (N = 22), transplanted after storage, did not result in IYSV-infected plants.

Rainfall variability in Northeast Thailand during 2000-2015 was examined with objectives to determine any changes in rainfall pattern with time, and to determine its effects on duration of rice growing period and grain yield using a simulation model. Variation in mean annual rainfall over 16 years in 93 locations in the region ranged from over 1,600 to less than 1,200 mm, and the locations were grouped into 4 based on the annual rainfall. The change in annual rainfall, and early, mid and late season rainfall was analysed for the rainfall groups. There was a significant reduction in the amount of early season rainfall during the 16-year period in all groups. However, there was no significant change for annual, and mid and late season rainfall. Simulation study showed that the start of rice growing period (SGP) was delayed with reduced early rainfall during the 16 year period and the end of rice growing period (EGP) was also delayed while there was no significant change for the length of rice growing period (LGP). Simulation results showed that grain yield of KDML105, leading variety in Thailand, tended to increase during the 16 year period, as delayed planting time was optimum for achieving maximum yield in all rainfall groups. With general delay in rainfall season, occurrence of late season drought was predicted to be reduced and this helped to increase simulated grain yield. However, adaptation to changing rainfall pattern needs to be planned in advance to maximize its effect.

Arctic warming is affecting snow cover and soil hydrology, with consequences for carbon sequestration in tundra ecosystems. The scarcity of observations in the Arctic has limited our understanding of the impact of covarying environmental drivers on the carbon balance of tundra ecosystems. In this study, we address some of these uncertainties through a novel record of 119 site-years of summer data from eddy covariance towers representing dominant tundra vegetation types located on continuous permafrost in the Arctic. Here we found that earlier snowmelt was associated with more tundra net CO2 sequestration and higher gross primary productivity (GPP) only in June and July, but with lower net carbon sequestration and lower GPP in August. Although higher evapotranspiration (ET) can result in soil drying with the progression of the summer, we did not find significantly lower soil moisture with earlier snowmelt, nor evidence that water stress affected GPP in the late growing season. Our results suggest that the expected increased CO2 sequestration arising from Arctic warming and the associated increase in growing season length may not materialize if tundra ecosystems are not able to continue sequestering CO2 later in the season.