Reducing nitrogen (N) fertilizer application is a sustainable practice in rice production. The effects of reducing N fertilizer input on grain yield and rice quality of early- and late-season dual-use rice (ELDR) in South China remain uncertain. Therefore, a short-term field trial was conducted with a high-yielding ELDR cultivar (Yuehesimiao, YHSM) and a low-yielding ELDR cultivar (Meixiangzhan 2, MXZ). The rice was cultivated with a 20% reduced N application rate (RN2), a 10% reduced rate (RN1) and the conventional N application rate (CN). In the early season, compared to CN, RN2 reduced the grain yield of YHSM and MXZ by an average of 16.1 and 6.6%, respectively, while RN1 lowered YHSM grain yield by 11.2% on average and had no effect on MXZ yield. In addition, RN2 decreased the milling and eating qualities of the two cultivars in the early season, while RN1 did not alter their milling, appearance or eating qualities. In the late season, neither RN2 nor RN1 affected grain yield or rice quality for both cultivars. Therefore, short-term reductions of 10 and 20% in N application could maintain grain yield and rice quality at current N fertilizer application rates in the late season. However, the early-season results only recommended a 10% reduced N fertilizer application rate for low-yielding ELDR cultivars to sustain grain yield and rice quality. The findings of this study can provide a theoretical basis for N management of ELDR in South China.

Currently, a limited number of herbicides is available to treat water-seeded rice in California, with widespread resistance to most of those herbicides. Because no resistant grasses showed resistance to pendimethalin, a series of studies were conducted to evaluate water-seeded rice response to pendimethalin. In a field study conducted at the Rice Experiment Station at Biggs, California, in 2020 and 2021, three pendimethalin formulations, a granule (GR), emulsifiable concentrate (EC), and capsule suspension (CS), were applied at 1.1, 2.3, and 3.4 kg ai ha−1 rates, and at 5, 10, and 15 d after seeding onto water-seeded rice. In addition, a greenhouse study was conducted to examine the response of five common California rice cultivars to GR and CS formulation applications. Echinochloa control levels were reduced at 15 d after seeding after use of EC and CS formulations compared with earlier timings. In both years, rice grain yields were increased by 3,014 kg ha−1 after application of pendimethalin at 3.4 kg ai ha−1 when applied at 15 d after seeding compared with 5 and 10 d after seeding, and similar to 1.1 kg ai ha−1 applications. The GR and CS were safer formulations based on a reduction in injury and an increase in grain yields compared to the EC formulation. Differences in seedling vigor across cultivars appeared to incur an advantage after a pendimethalin application. However, most cultivars evaluated for stand reduction and dry biomass demonstrated tolerance to GR and CS formulation applications only after rice reached the 3-leaf stage. In contrast, an application at 1-leaf stage rice reduced stand up to 68%. Application rate, timing, and formulation are important factors to consider if the use of pendimethalin in water-seeded rice is to be pursued.

This study uses a marginal treatment effects approach and farm household rice survey data from Northern Ghana to examine the heterogeneous effects of agricultural technologies on household welfare. Results indicate significant heterogeneity in the gains from the adoption of improved rice technologies among farmers. We found significant evidence of a pattern of positive selection on unobserved gains from the adoption of agricultural technologies on rice yield and household dietary diversity scores (HDDS). Moreover, the policy-relevant treatment effects suggest that reducing the distance to sources of agricultural technologies increases rice yield and HDDS through technology adoption.

The current paper tackles a critical question in climate change literature of whether farmers will be able to fully adapt to monsoonal climate changes owing to technological developments. Making use of the climate, agricultural and social data of Thailand from 1900 to 2015, this paper estimates a technological change instrumental variable by the growth of the normalized rice yield per hectare of land. The estimation shows that 0.98 of the growth in rice yield can be attributed to technological changes while the rest is accounted for by climate, soils and social factors. In the second stage regressions with the technological change indicator, the paper estimates the normalized numbers of the six most important types of live animals in Thailand: goats, chickens, cattle, sheep, pigs and buffaloes. Over the time period studied, the number of each of these live animals has increased vastly, except for buffaloes. The second-stage regressions show that the growth is largely attributable to technological changes, but monsoonal climate variables such as normalized monsoon precipitation ratio and normalized monsoon temperature are not significant factors. The results indicate that the rate of technological changes is overwhelming the rate of climate change on agriculture in Thailand.

Acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid} applied alone and in mixtures with propanil [N-(3,4-dichlorophenyl)propanamide] reduced rough grain yield of rice (Oryza sativa L. ‘Lebonnet’ or ‘Bond’) by 7% when applied at the late-booting or heading growth stages, averaged over several rates of application. Earlier applications did not reduce rice yield. The highest rate (0.6 kg ai/ha) of acifluorfen alone and in mixtures with propanil at 3.4 kg ai/ha reduced grain yields more than lower rates (0.1 or 0.3 kg ai/ha). Triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid} alone and in mixtures with propanil reduced rough grain yields of rice by 18% when applied at the late-booting growth stage, averaged over several rates of applications, but did not affect yields when applied at the early-tillering, jointing, or early-booting growth stages. Whole-grain milling yield and germination of rice seed were not affected by acifluorfen or triclopyr alone or in mixtures with propanil, regardless of rate or growth stage of application.

Whether season-long weed control can be achieved in a furrow-irrigated rice system with similar herbicide inputs to that of a flooded system is not known. Field experiments were conducted in 2007 and 2008 at Pine Tree, AR to evaluate different herbicide programs on the weed control efficacy and rice grain yield in furrow-irrigated and flooded rice production systems. Six herbicide programs were evaluated with and without additional late-season “as-needed” herbicide treatments. Minor injury to rice was noted for quinclorac plus propanil. However, the injury was transient and the plants fully recovered. Overall weed control was greater in the flooded system compared with the furrow-irrigated system (up to 20% greater), because flooding effectively prevented the emergence of most terrestrial weeds. In addition, rice grain yields were 13 to 14% greater in flooded compared with furrow-irrigated plots. Irrespective of the irrigation system, herbicide programs that contained a PRE-applied herbicide provided greater weed control and resulted in greater yield compared with those that did not contain PRE-applied herbicide, indicative of the importance of early-season weed control in achieving higher grain yields. On the basis of weed control, yield, and weed treatment cost, the herbicide program with clomazone PRE followed by propanil at four- to five-leaf rice was more efficient than other programs evaluated in both irrigation systems. However, furrow-irrigated plots required as-needed herbicide applications, which were applied after the four- to five-leaf rice stage when two or more plots within a program exhibited ≤ 80% control for any of the weed species. This suggests that furrow-irrigated rice production demands additional weed management efforts and thereby increases production costs. There is also a possibility for substantial yield reduction in the furrow-irrigated system compared with the flooded system. Nevertheless, furrow-irrigated rice production can still be a viable option under water-limiting situations and under certain topographic conditions.

Intensive selection pressure from repeated use of propanil and quinclorac led to the evolution of herbicide-resistant barnyardgrass biotypes. Twenty-two composite field samples were tested for level of resistance in 2002 and 2003, and field studies were conducted at the Rice Research and Extension Center, Stuttgart, AR, in 2002 and 2003 to evaluate alternative rice herbicides to control propanil-resistant (PR) and quinclorac-resistant (QR) barnyardgrass. Of the 22 composite samples, four were PR (30 to 40% control); four had a mixed population of PR, QR, and susceptible (S) barnyardgrass; and two had multiple resistance to propanil and quinclorac (P/QR), with control from propanil of 15 to 30% and control from quinclorac of 5 to 10%. ‘Wells’ rice was used where conventional herbicide programs were evaluated, and Clearfield rice ‘CL-161’ (imidazolinone-resistant) was used for herbicide programs involving imazethapyr. All PR and QR barnyardgrass were controlled > 90% by alternative herbicides, including all preemergence (PRE) and delayed preemergence (DPRE) treatments. By 56 d after emergence (DAE), cyhalofop or fenoxaprop applied to two- to three-leaf barnyardgrass (early postemergence [EPOST]), followed by (fb) a preflood application, controlled barnyardgrass > 93%. Pendimethalin controlled PR barnyardgrass 21 DAE, but not all season long. In contrast, imazethapyr in Clearfield rice controlled all grass weeds 100% all season long. Midpostemergence (MPOST) bispyribac application at the four- to five-leaf stage also provided season-long control of all barnyardgrass biotypes (> 88%, 56 DAE). Rice yields ranged from 5,300 to 5,700 kg ha−1 in conventional weed-control treatments and from 2,800 to 5,000 kg ha−1 in imazethapyr-treated plots. Nontreated plots yielded 1,500 kg ha−1.

We evaluate the effects of climate change on Vietnam's rice market. Results suggest that under a low-emission scenario and without interventions, rice production would drop by as much as 18% by 2030 relative to the 1980–1999 average. Farm and wholesale prices would increase by 1.86%, causing domestic demand to fall by 0.38%. The export sector would experience a rise of 6.94% in export free-on-board prices and a drop of 55.36% in export quantities. Farmers would experience a sales loss of 16.02%, whereas wholesalers would see a sales gain of 1.48%. For exporters, their sales loss would amount to 48.42%.