Rice-wheat comparative genomics:Gains and gaps

Rice and wheat provide nearly 40%of human calorie and protein requirements.They share a common ancestor and belong to the Poaceae(grass)family.Characterizing their genetic homology is crucial for developing new cultivars with enhanced traits.Several wheat genes and gene families have been characterized based on their rice orthologs.Rice–wheat orthology can identify genetic regions that regulate similar traits in both crops.Rice–wheat comparative genomics can identify candidate wheat genes in a genomic region identified by association or QTL mapping,deduce their putative functions and biochemical pathways,and develop molecular markers for marker-assisted breeding.A knowledge of gene homology facilitates the transfer between crops of genes or genomic regions associated with desirable traits by genetic engineering,gene editing,or wide crossing.

Diversity and Plant Growth Promoting Ability of Culturable Endophytic Bacteria in Nepalese Sweet Potato

There is no information on Nepalese sweet potato endophytes. We isolated 243 endophytic bacteria belonging to 34 genera in six classes from 12 locations of Nepal. Among them, the predominant classes were Bacilli and Gammaproteobacteria. The principal component analysis revealed that the composition of bacterial classes was unrelated to the environmental parameters of the sampling sites. Regarding their plant growth promoting potentials, 57% of the strains demonstrated indole-3-acetic acid (IAA) producing ability while 5% strains had nitrogen fixing gene (nifH) and acetylene reduction assay (ARA) activity. The representative strains in all six classes showed antagonistic effect against bacterial pathogens while only Bacillus strain showed the effect against fungal pathogen. For endophytic traits, cellulase activity was observed in 5 classes, while pectinase activity was only in Proteobacteria. Fresh weight and vine length of sweet potato increased by inoculating mixed cultures of the isolates from each location.

New Agri-Silvo-Pastoral Model Utilizing Terrace RiserEnhancing Crop and Livestock Production Developed inNepal

Twelve fodder species with maize (Zea mays) and millet (Eleusine coracana) were evaluated under agri-silvo-pastoral system along the Terrace risers (T-risers) of cropping land in the Agricultural Research Station Pakhribas, Nepal. Major aim of innovative agroforestry experiment designed and tested first time in Nepal was to utilize one-third land in risers of cropping terraces due to limited lands of smallholders to produce green fodders needed for livestock. Trees were planted at 1.5 m on the terrace edges and ground fodders at 30-50 cm on the risers. Trees were not allowed to grow tall to avoid shade effect on crops grown in terraces. They were felled at breast height in second year growing coppices for fodder. The results showed higher survival (76% to 100%), growth (1-3 m high) and yield of improved forages and fodder trees indicating potential for cultivation on T-risers. Dry matter (DM) of tree fodders varied 31%-49%, and ground fodders 19%-32%. DM yields ranged 3.0 t/ha (Stylosanthes guanensis) to 26.5 t/ha (Pennisetum purpureum). Combined effects of fodder species on major hill crops, maize and finger millet growth, yield and other attributes were monitored in the terraces. Most mean data were significant and at par between the treatments. Better combinations of tree and ground fodders for higher grain and stover yields (3.1 t/ha and 3.4 t/ha, respectively) of maize were Grewia optiva/Thysalonaema maxima, Desmodium intortum, Ficus auriculata/Setaria anceps, D. intortum (2.7 t/ha and 3.3 t/ha, respectively). Promising combinations for finger millet growth and yields (2-3 t/ha) were G. optiva/T. maxima, Bauhinia purpurea/S. anceps, F. semicordata/P. cetaceum. Soil analysis result showed positive impact of fodders on the risers where organic matter was highly increased after three years. Farmers and stakeholders also evaluated this technology that has been successful and recommended for similar ecological regions.

Tillage, crop residue, and nutrient management effects on.soil organic carbon in rice-based cropping systems： A review

Soil organic carbon （SOC） sequestration is one of the major agricultural strategies to mitigate greenhouse gas （GHG） emissions, enhance food security, and improve agricultural sustainability. This paper synthesizes the much-needed state- of-knowledge on the effects of tillage, crop residue, and nutrient management practices on SOC sequestration and identifies potential research gap, opportunities, and challenges in studying SOC dynamics in rice （Oryza sativa L.）-based cropping systems in South Asia, mainly in Bangladesh, Bhutan, India, Nepal, Pakistan, and Sri Lanka. Improved management prac- tices such as reduced- and no-tillage management, nitrogen （N） fertilizer and farmyard manure （FYM） application, and crop residue addition can improve SOC accumulation. Positive effects of no-tillage, crop residue addition, N addition through manure or compost application, and integration of organic and chemical fertilizers on SOC accumulation in rice-based cropping systems have been documented from South Asia. However, limited data and enormous discrepancies in SOC measurements across the region exist as the greatest challenge in increasing SOC sequestration and improving agricultural sustainability. More research on SOC as influenced by alternative tillage, crop residue, and nutrient management systems, and development of SOC monitoring system for existing long-term experiments will advance our understanding of the SOC dynamics in rice-based cropping systems and improve agricultural system sustainability in South Asia.

Design and Experiment of ф-type-knots Knotters on Chinese Small Square Balers

Since the knotters on the Chinese rectangular balers are imported from outside of the country, Chinese knotters with independent intellectual property rights is far away from being closed. In order to harvest a large quantity of straw in a short period on the small-scale lands of China, basic requirements on the knotters are summarized. Mathematical model of the knotter is also determined uniquely. Furthermore, the ^-type-knots knotter equipped on the Chinese square baler to form the ~ type knots is designed. Knotting rate experiments of the qb-type-knots knotter on the test bench and in the wheat/maize straws covered fields are carried out to check the knotting performances of the knotter. The parameters of the formed knots are also tested. The experiments results show that the knotting rate of the qb-type-knots knotter reaches 100.0% on the test bench without straws, while reaches 99.6% in the wheat straws covered field and 100.0% in the maize straws covered field. The average maximum force in the knotting process is 194.7 N in the lab experiment. The length out of the knots formed in lab is 15.9%-20.6% lower than the knots formed in the field experiment. The breaking force of the knots formed in the field is 115.9%-167.2% higher than the knots formed in lab due to the higher preload and interactions with the compacted bales. Highly relevant relationships exist between the breaking force of the formed knots and the maximum force in the forming process of the knots in the lab experiment. The designed knotter breaks out the embarrassing situation of the domestic knotters which don＇t have independent intellectual property rights, and promotes the development of Chinese knotter technology, and the mathematical model is helpful for designing new type of knotters.

A proposed surface resistance model for the Penman-Monteith formula to estimate evapotranspiration in a solar greenhouse

Greenhousing is a technique to bridge season gap in vegetable production and has been widely used worldwide. Calculation of water requirement of crops grown in greenhouse and determination of their irrigation schedules in arid and semi-arid regions are essential for greenhouse maintenance and have thus attracted increased attention over the past decades. The most common method used in the literature to estimate crop evapotranspiration（ET） is the Penman-Monteith（PM） formula. When applied to greenhouse, however, it often uses canopy resistance instead of surface resistance. It is understood that the surface resistance in greenhouse is the result of a combined effect of canopy restriction and soil-surface restriction to water vapor flow, and the relative dominance of one restriction over another depends on crop canopy. In this paper, we developed a surface resistance model in a way similar to two parallel resistances in an electrical circuit to account for both restrictions. Also, considering that wind speed in greenhouse is normally rather small, we compared three methods available in the literature to calculate the aerodynamic resistance, which are the r_a^1 method proposed by Perrier（1975a, b）, the r_a^2 method proposed by Thom and Oliver（1977）, and the r_a^3 method proposed by Zhang and Lemeu（1992）. We validated the model against ET of tomatoes in a greenhouse measured from sap flow system combined with micro-lysimeter in 2015 and with weighing lysimeter in 2016. The results showed that the proposed surface resistance model improved the accuracy of the PM model, especially when the leaf area index was low and the greenhouse was being irrigated. We also found that the aerodynamic resistance calculated from the r_a^1 and r_a^3 methods is applicable to the greenhouse although the latter is slightly more accurate than the former. The proposed surface resistance model, together with the r_a^3 method for aerodynamic resistance, offers an improved approach to estimate ET in greenhouse using the PM formula.

Performance of Medicinal and Aromatic Chamomile (Matricaria chamomilla L.) under Different Planting, Manure cum Fertilizer Regimes in Kathmandu Valley

New and old genotypes of German chamomile(Matricaria chamomilla Linn.)were experimented under different planting methods,manure and fertilizer combinations first time in Kathmandu valley.The researches aimed at evaluating genotypes performance,identifying suitable planting method and optimum combination of manures and fertilizers.The germplasm evaluation experiment was conducted at the National Agriculture Research Institute(NARI)field,Khumaltar during January-May.Planting method trial was laid out in randomized complete block and manure cum fertilizer trial was in Latin square design(LSD).The results showed good performance of chamomile growth,development and oil content.Major agronomic traits had average figures in all experiments comparable to chamomile growing areas.Most data differed significantly and at par.New genotype produced relatively higher number of branches,leaves and flower heads maintaining more plant density.Growth was higher in row sown and transplanted plots,row sowing found more beneficial.Transplanted plots delayed maturity.Transplanted(0.95%)and broadcasted(0.80%)chamomile gave higher oil percentage,no difference found between genotypes.Significantly(p<0.05)higher and at par branch numbers,flower heads,biomass yield,plant height were recorded in the treatments with higher rate of farm yard manure(FYM)20 t/ha followed by combined application of NPK 60:40:20 kg/ha plus manure 10 t/ha.Oil content was the highest(0.95%)in FYM(20 t/ha)applied plots followed by combined fertilization(0.80%).Despite inferior to treatment N:P:K 60:40:20 kg/ha only to enhance growth and oil production,other results suggested suitable technology and successful cultivation of chamomile in valley conditions are recommended.

Effects of Rice Husk and Rice Husk Charcoal on Soil Physicochemical Properties, Rice Growth and Yield

To investigate the effect of the application of rice husk (RH) and rice husk charcoal (RHC) on soil properties and rice production, pot experiment comprising of five treatments was conducted. Soil was mixed at the rate of 0 (control), 2% and 4% (w/w) with RH and RHC, respectively with randomized complete block design (RCBD). RHC incorporation had a potential to reduce the acidity of the soil, whereas, RH incorporation had almost no effect on the pH of the soil. RH and RHC amendment both increased the saturated hydraulic conductivity, saturated water content, plant available water and field capacity but decreased the bulk density of soil. Crop growth components at harvest revealed that the highest plant height was recorded in RH4%. However, for the panicle length, panicle weight and number of tillers, the highest value was found in RHC2%, 14.2 cm, 4.0 g and 28.8 cm, respectively. Furthermore, number of panicle, 1000-grains weight and grain yield were also found highest in RHC2%, 22.4 g and 4.41 t/ha, respectively. However, for the number of grain per panicle and percentage of filled grain, the highest value was found in RH4%, 79.0 and 88.5, respectively. The grain yield increased by 38%, 28%, 18% and 22% and the biological yield increased by 27%, 18%, 14%, and 16% for RHC2%, RHC4%, RH2%, and RH4%, respectively, compared to that of the control;however, the significant difference was found only for RHC2% for both. The harvest index increased under all application rates of RH and RHC compared to that of control.

Energy balance and environmental impacts of rice and wheat production:A case study in Nepal

Energy and environment are the key concerns in todays’agriculture.This study investigated energy balance and environmental impact of rice and wheat production systems in terms of energy ratio,impact of energy inputs to the crop yield and CO2e(carbon dioxide equivalent)emissions under terai and hill geographical regions of Nepal.Primary data were collected from 139 randomly selected farms by using structured questionnaire.The results revealed that the total energy consumption in rice and wheat production were 9.70 GJ/hm^(2)(terai)to 11.78 GJ/hm^(2)(hill)and 8.40 GJ/hm^(2)(hill)to 10.95 GJ/hm^(2)(terai),respectively.The energy balance of rice and wheat production were found 46.33 GJ/hm^(2)(hill)to 59.29 GJ/hm^(2)(terai)and 27.14 GJ/hm^(2)(terai)to 38.52 GJ/hm^(2)(hill),respectively,where energy use efficiency in terai and hill were found to be 7.14 and 4.97 in rice,and 3.49 and 5.59 in wheat,respectively.The contribution of fertilizer on impacts was significant among other energy inputs in rice and wheat production in both geographical regions.The CO_(2)e emissions from rice and wheat were higher by 52%and 78%in hill as compared to respective crop rice(1786 kg CO_(2)e/hm^(2))and wheat(843 kg CO2e/hm^(2))in terai.This study showed that rice production system in terai is more energy and environmentally efficient,whilst wheat production in hill is more energy efficient.