Rubber is usually cultivated for lifespan of 30 years based on the technical feasibility of managing tapping panels. For obtaining early financial benefits, there is a demand for shorter lifespan with intensified tapping. With no research conducted on this line, the present study was focussed to investigate the financial feasibility of shortening the lifespan of rubber trees through lifecycle analyses with three principal scenarios of intensified harvesting, i.e. Intensified Harvesting throughout the Total harvesting Period to obtain a part or full amount of yield lost due to shortening the lifespan (IHTP), Intensified Harvesting only during last 6 Years (IH6Y) and Intensified Harvesting at last ¼ of harvesting Period (IH¼P). In IHTP, intensified tapping to achieve 10–15% of yield loss due to shortening the lifespan was found to be effective to reduce the lifespan even up to 21 years. Market price of rubber and tree stand per hectare were found to be the critical factors determining the best lifespan particularly in IHTP. The best lifespan under IH6Y and IH¼P scenarios was in the range of 19–22 years. Agronomic, environmental and social implications in shortening lifespan of rubber are discussed.

Bud removal of the cuttings at underground level has been claimed by cassava growers in Thailand as a method to increase cassava yield. This practise should be tested experimentally to explain the reason for yield increase. The objective of this study was to investigate the effects of bud removal and cutting length on storage root yield and starch content of three cassava varieties. Field experiment was conducted in a split–split plot design with four replications in 2010 and 2011, under rainfed conditions. Three cassava varieties (KU50, RY9 and HB60) were assigned as main plot. Two cutting lengths (15 cm and 30 cm) were assigned as sub plots, and two treatments of buds (buds cut and not cut) were assigned as sub–sub plots. The buds on the cuttings that were inserted into the soil were removed. In 2010, the plants from 15-cm long cuttings subjected to bud removal had higher fresh storage root yield (88.4 Mg ha−1) than did plants from 30-cm long cuttings subjected to bud removal (75.8 Mg ha−1). Cutting of buds also had higher fresh storage root yield (89.1 Mg ha−1) than did non bud-cutting (75.0 Mg ha−1). KU50 had the highest fresh storage root yield (91.4 Mg ha−1), dry root yield (48.4 Mg ha−1) and starch yield (20.1 Mg ha−1). Cutting length of 15 cm had higher starch concentration in storage roots (25.6%) than did cutting length of 30 cm (24.2%). HB60 had the highest starch concentration (27.0%) among cassava varieties tested. The data in 2011 were similar to the data in 2010. The responses of varieties to bud removal and cutting length are discussed.

Topdressing of N fertilizer, whenever leaf greenness, as measured by Chlorophyllmeter (SPAD), falls below the threshold value can be used for site-specific N management in wheat cultivation. Herein, a field experiment was conducted to analyse the effect of SPAD-based N management on wheat productivity and N use efficiency during the dry season of 2010/11 and 2011/12 on acid lateritic soil of eastern India. The experiment had 12 treatments, with nine treatments combining three SPAD thresholds (38, 40 and 42) and three N levels (15, 25 and 35 kg N ha−1) as real time N management (RTNM), one fixed time N management (FTNM), one farmers’ fertilizer practise (FFP) and control (Zero N), with three replications. The grain yield of RTNM ranged from 90 to 113% as that of FTNM, but using considerably less N. Maintaining SPAD threshold of 40 up to heading stage by topdressing 25 kg N ha−1 at each time (N25S40) caused the highest grain yield (4483 kg ha−1). While saving 22.5 kg N ha−1 (18.8%), N25S40 increased agronomic N use efficiency by 58.5%, nitrogen recovery efficiency by 15.1% and partial factor productivity of applied N by 26.4% when compared with conventional fertilizer recommendations (i.e. FTNM). The SPAD-based N management strategy was found very promising in efficiently managing N fertilizer in wheat for improving wheat productivity and N use efficiency.

Weed management is the major challenge to the success of boro rice (rice grown during Dec–Jan to May–Jun, also known as summer rice) in Southern Asia. Herbicide seems to be a cost effective and strategic tool from an agronomic view point to control weeds; however, herbicide application can potentially interfere with soil enzyme activity and microbial biomass carbon (MBC). A field study was conducted in 2012/13 and 2013/14 to evaluate the performance of sole and combined application of different pre-emergence herbicides in comparison to manual weeding in boro rice. Lowest weed density, biomass and highest weed control efficiency (~83%) were recorded with the pyrazosulfuron ethyl, causing higher grain yield (6.7 Mg ha−1 in 2012/13 and 4.5 Mg ha−1 in 2013/14) than treatments with chlorimuron + metsulfuron-methyl, bensulfuron methyl + pretilachlor, butachlor fb 2,4D, butachlor and cono-weeder. Among, the herbicidal treatments butachlor caused lower grain yield and higher weed density and biomass when compared to the others. Although grain yield was highest in weed-free treatments but net returns and (B:C) benefit cost ratio was highest for pyrazosulfuron ethyl due to high cost of hand weeding. After 15 days of herbicide application, lowest microbial biomass carbon was recorded with bensulfuron methyl + pretilachlor, whereas lower values of dehydrogenase and fluorescein diacetate activities were observed with the application of chlorimuron + metsulfuron-methyl at 15 days after herbicide application. Our results suggest that pyrazosulfuron ethyl is one broad-spectrum and economically effective herbicide for controlling weeds as an alternative to labour consuming hand weeding in boro rice cultivation.

As zinc (Zn) fertilizer and water management affect the expression of Zn-enriched grain traits in rice, we studied the effect of Zn fertilizer and water management on Zn uptake and grain yield of different biofortification breeding lines and the possible biases in selection for high grain Zn content. The first field experiment showed that longer duration genotypes had higher grain Zn uptake rate than shorter duration genotypes during grain filling. In the first greenhouse experiment, neither application of Zn fertilizer at mid-tillering nor application at flowering significantly increased the grain Zn concentration. In the second greenhouse experiment, application of alternate wetting and drying (AWD) significantly increased the available soil Zn and plant Zn uptake but not grain Zn concentration. Terminal drying (TD) did not increase the available soil Zn or grain Zn contents. The second field experiment confirmed that differences in TD were not important in understanding differences between genotypes. Zn application is not always necessary to breeding trials unless there is a severe Zn deficiency and there is no need to carefully regulate TD prior to harvest.

The sea asparagus Sarcocornia ambigua is a widespread coastal halophyte of South America that has a recent history of successful cultivation with saline shrimp farm effluent and nutritional quality for human and animal diets, as well as chemical characteristics for biofuel production. Two morphologically distinct lineages (BTH1 and BTH2) of S. ambigua were obtained by crossing pure lineages of natural biotypes. The growth and biomass production of f3 and f4 progenies of S. ambigua lineages were evaluated, as well as their macro- and micro-mineral components were investigated by spectrophotometry. The BTH2 lineage showed a 43% higher shoot growth rate, a two times faster branch production and a higher biomass allocation to shoots than in BTH1. BTH1 shoots showed higher concentrations of N, K and Cu than did the BTH2 progenies. The average levels of N, K, P and Ca in BTH1-f4 shoots were higher than those in wild plants of S. ambigua and ranked in the mid-upper range of these mineral contents in other species of the subfamily Salicorniodeae and gourmet vegetables. The mineral profile of the two selected lineages of S. ambigua confirms high nutritional quality of these plants for humans and animals. They can be presented as alternatives to food production with saline effluent from aquaculture on the temperate and tropical coast and/or inland salt-affected soils of South America.

The phenological development of crops from emergence to flowering time is largely controlled by temperature and photoperiod. Flowering time is a critical phenological stage for subsequent reproductive phase. Lotus tenuis management in grasslands, pastures and seed production systems is through defoliation and sowing date; however, yet little is known about their effects on flowering time. The data presented in this study were obtained from experiments conducted with L. tenuis during the years 1989 to 2016 under field conditions. Our objectives were to determine if flowering time (a) is affected by sowing date; (b) can be predicted through equations using temperature and photoperiod and (c) is affected by defoliation applied at vegetative stage. Two defoliation intensities were applied, low (LDI) crop height reduced by 54% compared to pre-defoliation crop height and high (HDI), crop height reduced by 75%. The rate of progress from seedling emergence to flowering time (inverse of time from emergence to first flowering, 1/f) was modulated by temperature, photoperiod and photothermal functions. When L. tenuis sowing was delayed from autumn to spring, time from seedling emergence to first flowering decreased from 260 to 100 days. 1/f was linearly related to average temperature (R²=0.75) and photoperiod (R²=0.85) and both variables (R²=0.92). Defoliation retarded flowering time. Flower and pod growth periods were shorter under defoliation than in control one. Defoliation did not cause abortion of flowers and pods. Flower production was fitted to quadratic function of photoperiod. Flowering peak was approximately within 15.2 h. The prediction of flowering time using thermal, photoperiod and photothermal models can provide information about crop management decisions, such as optimal environmental regimes for crop growth through sowing date.

Bhutan is a small country in the Himalayan mountains where subsistence agriculture is practiced due to small land holdings and undulating mountainous terrains. Due to diverse altitudinal and agro-ecological environments, many food crops are cultivated. Wheat is currently a secondary cereal, grown over an area of 1,964 ha with a total production of 3,465 Mg. While there are enormous opportunities to increase wheat production in Bhutan, it is challenged by numerous biotic and socio-economic factors such as labour shortage and low economic return. Among the biotic constraints, stripe rust and leaf rust are the most important diseases. Stem rust has not yet been reported. Poor crop nutrition, both through low soil fertility and inadequate external supply, also results in low productivity. In addition, better remunerative crops and affordable-imported products discourage wheat production. However, the availability and accessibility to higher yielding disease-resistant varieties, fertilization (both organic and inorganic), appropriate seed rate, optimum planting time, mechanization, rotation with legumes and expansion of wheat area are some measures that will play a crucial role in managing sustainable wheat production in Bhutan. In this paper, we provide a brief overview of the current scenario of wheat production, discuss the constraints and provide strategic guidance to improve wheat production in Bhutan.

Many types of weeds occur in cassava fields causing enormous yield losses due to competition for nutrients, light and space. The purpose of this study was to evaluate the growth and yield of four traditional varieties of cassava (Bonoua Blanc, Tambou, Yassé and Six mois) produced in Côte d'Ivoire and select the highest tolerant variety to weed competition. Six treatments were induced by varying the period in which cassava varieties were grown with weeds. Varieties and exposure time to competition with weeds significantly affected the productivity of cassava. The number of leaves per plant (NLP), the number of tuberous roots per plant (NTRP) and the weight of tuberous roots per plant (WTRP) declined with increasing duration of weed presence. After an initial period of weeding, the first four months of grassing proved critical for the four varieties. Despite the presence of weeds, Bonoua Blanc has higher growth and yield than Tambou, Yasse and Six mois. This suggests that Bonoua Blanc was more tolerant to weed competition than the others from planting to harvest, being a suitable variety in intercropping systems.

Nematode infestation in Sub-Saharan Africa's (SSA) cropping systems, worsened by poor crop rotations, is a major factor contributing to limited utilisation of applied nutrients and water, leading to low maize (Zea mays L.) yields particularly on sandy soils. The effects of nematode infestation on maize productivity were evaluated under conservation agriculture (CA) on granitic sandy soils in sub-humid smallholder farms of Goromonzi district of Zimbabwe. Four treatments were tested for three seasons on six smallholder farmers’ fields in a randomised complete block design, each farm being a replicate: fenamiphos 40EC (a commercial synthetic nematicide), lime + fenamiphos 40EC, lime and an untreated control. Results of the study showed that independent application of fenamiphos 40EC and lime significantly reduced plant parasitic nematode infestations in maize roots by more than 10 times those present in the untreated plots while maize yield also increased significantly. Yield increase from fenamiphos and lime applications amounted to 53 and 42% respectively, compared to the untreated controls. Maize yield was negatively correlated with density of Pratylenchus spp. nematodes. Nematode management strategies involving fenamiphos 40EC or lime could significantly reduce maize yield losses in maize-based smallholder farming systems of SSA under CA. It was more economical to use fenamiphos than lime to control nematodes.

We regret that the computer program used to generate the simulations of the examples presented in Owusu-Ansah, Curnow and Adu-Ampomah, 2013 contained an error. The corrected simulations for trial M2 now show that a single replication of many clones gives slightly higher selection gains than greater replication of fewer clones. The very small advantages of large numbers of years of harvest remain correct. The selection gains from the trials were considerably underestimated and, with the corrected simulations, the expected performance in terms of yield of the selected clones with the right combination of numbers of clones and replicates often exceeded the performance of the best standard clone. The selected clones still underperformed compared with the best standard clone when selection was based on percentage of diseased pods or numbers of healthy pods.

Legumes are essential to meet nutrition need of growing population in Afghanistan but have low productivity under the farmer practices. With an aim to introduce improved varieties of chickpea (Cicer arietinum) and mung bean (Vigna radiata) along with associated cultivation practices, a number of on-farm demonstration trials were conducted in eight districts covering three provinces to assess their performance in comparison with local practices. The data or information generation from on-farm trials is routine but remains unutilized under the commonly used analysis based on frequentist approach. This study makes use of such prior information to widen the statistical inference framework using a Bayesian approach (BA) for analysing any future on-farm trials. The statistical analysis evaluated the mean performance of the improved and local production packages and risks associated with them to meet a given target. Evaluated at the two districts during 2012, the improved variety of chickpea (Madad) yielded higher than the farmer variety (2.25–2.40 vs. 1.93–1.94 Mg/ha), while that of mung bean (Mash 2008) yielded higher than the farmer variety (1.22–1.24 vs. 0.93–0.94 Mg/ha), both with high probability. The stochastic dominance analysis showed that the recommended package with improved variety Madad has 95% probability of achieving a target of 2 Mg/ha while such a target for local practice was around its one-third when cultivated in Baghlan-e-sannati district. Crossover in the risk curves helped to identify and quantify the region specific risk to meet a given target. BA is then recommended in the analysis of on-farm trials data.