Number Of Panicles Research Articles

Response of scented rice landraces of North Bengal under organic nutrient management in Darjeeling hills

The traditional practice of growing scented rice in Darjeeling Himalayas needs refinement in nutrient management for sustained production with desired quality. The effect of organic nutrient sources (Cow dung manure @ 5 t/ha, Vermicompost @ 1.5 t/ha, Mustard cake @ 0.5 t/ha, and Leaf mould @ 1 t/ha) on two aromatic rice cultivars (Kalture, and Kalonunia) was studied in a split-plot design during wet (kharif) season of 2021 at Uttar Banga Krishi Viswavidyalaya, Kalimpong, West Bengal. Kalture had taller plants (137.1 cm) and lodging susceptibility (score 4.0) at harvest, while Kalonunia remained unlodged. Kalonunia produced 16.1% greater grain yield (3.32 t ha-1 vs. 2.86 t ha-1) over Kalture due to more number of panicles m-2 (356.2) and filled grains panicle-1 (90.1). Both aromatic rice cultivars had medium-slender (MS) white kernels, but Kalonunia had higher protein content (7.3%), alkali spreading value (score 6.0) and aroma (score 1.8) than Kalture (6.7%, score 5.7 and score 1.6). The application of vermicompost @ 1.5 t ha-1 resulted in higher grain yield (3.22 t ha-1), but mustard cake @ 0.5 t ha-1 might be better option due to moderate yield (3.11 t ha-1), better grain quality, and greater residual N (235.1 kg ha-1), P status (23.4 kg ha-1) in hill soil of West Bengal.

Genomic insights into Bacillus subtilis MBB3B9 mediated aluminium stress mitigation for enhanced rice growth

Aluminium (Al) toxicity in acid soil ecosystems is a major impediment to crop production as it drastically affects plant root growth, thereby acquisition of nutrients from the soil. Plant growth-promoting bacteria offers an interesting avenue for promoting plant growth under an Al-phytotoxic environment. Here, we report the plant growth-promoting activities of an acid-tolerant isolate of Bacillus subtilis that could ameliorate acid-induced Al-stress in rice (Oryza sativa L.). The whole genome sequence data identified the major genes and genetic pathways in B. subtilis MBB3B9, which contribute to the plant growth promotion in acidic pH. Genetic pathways for organic acid production, denitrification, urea metabolism, indole-3-acetic acid (IAA) production, and cytokinin biosynthesis were identified as major genetic machinery for plant growth promotion and mitigation of Al-stress in plants. The in-vitro analyses revealed the production of siderophores and organic acid production as primary mechanisms for mitigation of Al-toxicity. Other plant growth-promoting properties such as phosphate solubilization, zinc solubilization, and IAA production were also detected in significant levels. Pot experiments involving rice under acidic pH and elevated concentrations of aluminium chloride (AlCl3) suggested that soil treatment with bacterial isolate MBB3B9 could enhance plant growth and productivity compared to untreated plants. A significant increase in plant growth and productivity was recorded in terms of plant height, chlorophyll content, tiller number, panicle number, grain yield, root growth, and root biomass production.

Acidity and nutrient management practices for enhancing soil nutrient availability, nutrient uptake and grain yield of rice in Vaikom kari soils in Kuttanad, Kerala

A field investigation was conducted during August to December 2015 and 2016 in farmers` fields in Thalayazham panchayat in Kottayam district. The experiment was laid out in randomized block design having 16 treatments in three replications with rice (Oryza sativa L.) var. Uma. The treatments were dolomite, lime + MgSO4 or RHA (rice husk ash) + MgSO4 along with 100% package of practice (POP) alone or with 100% POP + foliar spray of 13-0-45 N-P-K (KNO3) (1%) or borax (0.5%) or 13-0-45 + borax at PI (panicle initiation) stage. Lime + MgSO4 + 75% POP + 13-0-45 + borax as well as lime without MgSO4 + 100% POP combined with 13-0-45 or borax or both were also included as treatments. Higher grain yield of 5.42 and 5.57 t ha-1 during 2015 and 2016 respectively were produced by dolomite + POP + 13-0-45 followed by dolomite + POP + 13-0-45 + borax and lime + POP + MgSO4 + 13-0-45. The treatments involving dolomite and lime with or without MgSO4 produced taller plants, higher tiller number m-2 and higher Leaf Area Index during both the years. Dolomite + POP + 13-0-45 produced the highest number of panicles m-2. Higher test weight and lower percentage of unfilled grains were observed with dolomite + POP + 13-0-45 and dolomite + POP + 13-0-45 + borax. Lime and dolomite treatments were more effective in reducing soil acidity and improving dehydrogenase activity and nutrient availability in the soil than RHA treatments during both the years. However, the effect of liming materials applied as basal and at 30 DAS diminishes after the crop and this necessitates application of liming materials in every crop season. Availability of soil N improved by treatments involving lime + POP without MgSO4 at PI and harvest stages. The treatments involving dolomite + POP and lime + POP with or without MgSO4 recorded higher available P during PI stage. In general, higher status of available K was registered by the treatments involving dolomite or lime application and lower K status registered by the treatment with 75% POP fertilizer. All treatments involving lime or dolomite registered higher soil available Ca and those involving dolomite or lime + MgSO4 showed higher availability of Mg in the soil. The treatments involving dolomite registered lower status of soil available Fe and higher status of available B. Higher status of available Zn was registered by the treatments involving dolomite or lime + MgSO4. Soil pH was significantly and positively correlated with available P, Ca and Mg and significantly and negatively correlated with available Fe in the soil. In general, higher uptake of macronutrients was observed with dolomite or lime + MgSO4 treatments along with 100% POP during both the years. Foliar spray of 13-0-45 recorded higher N and K uptake. Significant and positive correlation of grain yield with uptake of macro nutrients was also observed.

Pengaruh Pupuk Kandang dan Giberelin (GA3) Terhadap Produksi Benih Bayam Hijau (Amaranthus hybridus L.)

The high demand for spinach and the increasing number of people in the community are not supported by existing production. Efforts are needed to increase the production of spinach seeds to meet the needs. The purpose of this study was to determine the effect of manure doses and gibberellin concentrations on seed production and quality, of Amaranthus hybridus. This research was conducted from August to November 2022 in Munder Village, Yosowilangun District, Lumajang Regency. This study was designed with a factorial randomized complete block design (RCBD) with 2 factors and 3 replications. The first factor was the treatment of the dose of manure with 3 level of goat manure, (10 tons/ha, 20 tons/ha and 30 tons/ha). The second factor was the treatment of gibberellin concentrations with 3 gibberellin concentrations, (100 ml/l, 150 ml/l and 200 ml/l). Then the data obtained is tested using ANOVA, then followed with DMRT at error level 5%. The results showed that the dose of 30 tons/ha of manure had a very significant effect on the number of panicles 14.00 strands, biomass 77.66 gram. The treatment of gibberellin concentrations had a very significant effect on number of panicles (13.87 strands), stem diameter (0.8967 cm). The combination of the two treatments had a very significant effect on the weight of 1000 seeds (0.8929 gram).

Pengaruh Dosis Sekam terhadap Pertumbuhan dan Hasil Tanaman Padi (Oryza sativa L.) Varietas Inpari 32

The research aims to determine; (1) the response of growth and yield of rice plants to various doses of roasted husks, and (2) doses of roasted husks that have a positive effect on the growth and yield of rice plants of the Inpari 32 variety. The study was carried out for 3 (months) months, starting from January to March 2022. This research was carried out with an experimental approach using a Randomized Block Design (RBD), 6 doses of burnt husk treatment and repeated five times, so that there were 30 experimental units. The variables observed were plant height, number of tillers per clump, number of productive tillers per clump, number of shoots per clump, panicle length, number of pithy grain per panicle, weight of 1000 grains of grain, yield of dry grain harvested per clump and per plot. The data obtained in the study were analyzed by analysis of variance (ANOVA) if there was a significant effect, then Duncan's multiple-distance further test was carried out at a significance level of 5 percent. The results showed: (1) Burned husk treatment had a significant effect on plant height, number of tillers per clump, number of productive tillers per clump, number of panicles per clump, number of pithy grain per panicle, weight of 1000 grains of grain, yield of dry grain harvested per clump. and per plot, but had no significant effect on panicle length. and (2) The highest harvested dry grain yields were obtained at doses of roasted husks of 4 and 5 tons/ha, namely 6.65 kg and 7.70 kg per plot or equivalent to 7.39 tonnes per hectare and 8.56 tonnes per hectare.

Growth and yield performance of hybrid rice varieties under varying zinc levels

Zinc deficiency in soil is currently a widespread problem in Bangladesh that significantly reduces the yield of a variety of crops, including rice. Despite the fact that many farmers started applying zinc fertilizer, many are unaware of the right amount and application technique. For this reason, to determine the impact of variety and zinc treatment on the performance of hybrid rice, a field experiment was carried out between November 2019 and May 2020 at the Sher-e-Bangla Agricultural University's experimental field in Sher-e-Bangla Nagar, Dhaka-1207. The experiment consisted of two factors as variety (3 types) viz., V1 – BRRI hybrid dhan2, V2 – BRRI hybrid dhan3 and V3 – BRRI hybrid dhan5 and, Zinc management (4 levels) viz., Zn0 – 0 kg ha-1 (control), Zn1 – 2 kg ha-1, Zn2 – 4 kg ha-1 and Zn3 – 6 kg ha-1. The experiment was laid out in a Randomized Complete Block Design (Factorial) with three replications. Data on different growth and yield parameter of rice were recorded and significant variation was found for different treatments. Regarding varietal performance, the maximum panicle number hill-1 (17.10), panicle length (28.03 cm), grain number panicle-1 (109.45), 1000-grain weight (26.50 g), grain yield ha-1 (6.94 t), straw yield ha-1 (8.58 t), biological yield ha-1 (15.51 t) and harvest index (44.62%) were found from the variety BRRI hybrid dhan5. Considering Zn effect, the maximum panicle number hill-1 (16.33), panicle length (27.14 cm), grain number panicle-1 (108.11), 1000-grain weight (25.38 g), grain yield ha-1 (6.81 t), straw yield ha-1 (8.34 t), biological yield ha-1 (15.15 t) and harvest index (44.88%) were found from 6 kg Zn ha-1. In the case of treatment combination of variety and zinc, the maximum panicle number hill-1 (20.17), panicle length (29.45 cm), number of grains panicle-1 (117.74), 1000-seed weight (27.43 g), grain yield (7.80 t ha-1), straw yield (9.20 t ha-1), biological yield (17.00 t ha-1) and harvest index (45.78%) were found from BRRI hybrid dhan5 along with 6 kg Zn ha-1. Therefore, the hybrid rice variety BRRI hybrid dhan5 with a Zn application of 6 kg ha-1 yielded considerably more grain than the other treatment combinations under evaluation.

Red Rice (Oryza Nivara) Growth and Yield are Impacted by Seedling Age and the Concentration of Liquid Organic Fertilizer

This study aims to ascertain how seedling age and liquid organic fertilizer content interact and correlate with red rice growth and production. This study was conducted in Karya Mulya village, Kesambi district, Cirebon, West Java, from December 2020 to April 2021. The factorial randomized block design (RBD) research methodology was used. Plant height, tiller count, leaf color, number of active tillers, number of panicles per clump, panicle length, number of grains per panicle, weight of 1000 grains, dry weight of grain harvested per plot, and dry weight of grain milled per plot were the key observations. The findings indicate that at 35 days following planting, there was an interaction between seedling age and liquid organic fertilizer concentration on leaf greenness. While the number of tillers 35 days after planting was affected by seedling age independently. When applied 42 days after planting, liquid organic fertilizer had an impact on the number of productive tillers, the number of panicles per clump, the length of the panicle, the number of grains per panicle, the weight of 1000 grains, the dry weight of the grain harvested per plot, and the dry weight of the grain ground per plot.

Assessment of Post Emergence Herbicide Efficacy for Drone Spraying in Transplanted Rice (Oryza sativa L.)

A field experiment was conducted at Rice Research Centre, Agriculture Research Institute, Rajendranagar, Hyderabad during kharif, (2022) to assess the post emergence herbicide efficacy for drone spraying in transplanted rice (Oryza sativa L.). The experiment was laid out in randomized block design with 7 treatments and replicated thrice. Results revealed that among different doses of herbicidal treatments, post emergence application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 180 g a.i ha-1using drone recorded highest number of tillers at harvest, plant height at harvest, number of panicles at harvest, grain yield and low weed dry matter at 60 DAT. It was statistically on par with application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 120 g a.i ha-1 using knapsack sprayer, application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 150 g a.i ha-1 using drone, and application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 120 g a.i ha-1 using drone followed by application of penoxsulam 1.02% + cyhalofop-butyl 5.1% OD @ 90 g a.i ha-1 using drone followed by unweeded control.

Optimisation of Anaerobic Digestate and Chemical Fertiliser Application to Enhance Rice Yield—A Machine-Learning Approach

The present study evaluates the synergistic application of an anaerobic digestate for enhanced rice yield. The study utilised the digestate as a fertiliser with various inoculum-to-substrate (IS) ratios of anaerobic digestion from cow dung and water hyacinth (CW–BF) with combinations of NPK (16-22-22) fertiliser for rice yield optimisation. The outcome of the combined digestate and fertiliser application on rice cultivation was observed in terms of parameters such as the number of tillers, panicle number, panicle length, fertile panicles, and 1000-grain weight. The digestate combination of CW–BF:NPK (3:1:1) resulted in the highest grain yield (7521 kg/hectare) with increased panicle length, test weight, and more filled grains than the other combinations. Moreover, various machine-learning approaches were used to study the efficacy of the different combinations of applied fertiliser (cow dung, water hyacinth, and NPK). The gradient-boosting machine-learning model was appropriate for predicting the modelling based on the measured data. Principal component analysis revealed NPK as the first principal component with high loading values and the digestate as the second principal component, which indicates its crucial role in fertiliser preparation. Therefore, deploying such hybridised fertilisers using the proper statistical analysis and machine-learning approaches can improve rice yield, which would be essential for the socio-economic uplifting of marginal rice farmers.

Direct and Indirect Effects of Yield Contributing Traits in Rice (Oryza sativa L.)

At the Field Experimentation Centre of the Department of Genetics and Plant Breeding, 20 rice genotypes, including one check variety, were assessed in order to research genetic variability, heritability, genetic progress, correlation, and path coefficient for 13 quantitative features. In Kharif 2022, the experiment was carried out utilising a Randomised Block Design with three replications. Over the NDR 359 (check), BRRI DHAN-75 (26.133) and A.K.DHAN (23.067) demonstrated a greater yield. Number of spikelets per hill, Number of panicles per hill, Biological yield, Number of tillers per hill, Grain yield per hill, Harvest index, Panicle length, Test weight, Days to maturity, and Plant height all had high to moderate estimations of GCV, PCV, and Genetic Advance as Percent Mean. Estimates of heritability ranging from high to moderate, genetic progress for the quantity of spikelets per panicle, biological yield,plant height, and days to 50% blooming. At both the phenotypic and genotypic levels, grain yield showed a strong positive connection with biological yield, the number of spikelets per panicle, and harvest index. Harvest index and biological yield showed both genotypic and phenotypic positive significant direct influences on grain yield per hill. Thus, in the current experimental materials, these qualities are recognised as the effective and prospective for indirect selection for the increase of rice yield.

Determination of low‐temperature stress during the vegetative stage as a tool to predict plant yield in rice genotypes with contrasting tolerance levels

AbstractIn this study, the first aim was to develop a rapid and non‐destructive method for analysing rice genotypes' tolerance to low temperatures (LT) during the seedling stage. Using a growth parameter and a physiological parameter, a discriminant formula was developed to differentiate between tolerant and sensitive genotypes based on their LT tolerance score. The study identified several benefits of the discriminant formula, including its low classification error rate, scalability, and ability to be used in controlled and reduced environments. Additionally, a second study was conducted, which found a strong correlation between the LT tolerance score during the seedling stage and plant yield at the ripening stage in plants grown under field LT during the vegetative stage. Panicle weight was the main mediator of the effect of the LT tolerance score on plant yield, but the number of panicles per plant also played a role. Overall, the results suggest that the LT tolerance score can serve as an indirect selection factor for plants for both LT tolerance and plant yield. This is especially relevant for rice‐growing regions with temperate climates and LT at the beginning of the cultivation season.

Study on Genetic Variability for Quantitative and Quality Parameters in Rice (Oryza sativa L.)

Genetic variability is the prime and fundamental requirement for any crop breeding to develop superior varieties which yields more and fulfills the demanding requirements of increasing population.The current study investigates twenty genotypes of rice, including one check variety NDR-359, that were raised in the Field Experimentation Centre of the Department of Genetics and Plant Breeding, SHUATS, Prayagraj during Kharif 2022 using a Randomized Block Design with three replications.The best genotypes for grain yield per plant were chosen based on the mean performance of genotypes RNR – 1446, followed by MTU - 1121, JGL – 24423, and Rango Komal. All of the qualities under examination had significant differences, according to the analysis of variance. The characters viz., Biological yield, Grain yield per hill, Number of spikelets per panicle exhibited high Genotypic Coefficient of Variation (GCV) and Phenotypic Coefficient of Variation (PCV). For all the features under study, there were very slight variations between GCV and PCV, indicating that the environment had little to no impact on these individuals. High heritability recorded in Biological yield (95.92%), Grain yield per hill (91.89%), Panicle length (91.80%), Plant height (91.00%) and Days to 50% flowering (87.81%), whereas moderate heritability observed in Flag leaf width (47.08%). High heritability coupled with genetic advance as percent mean is recorded in Biological yield (77.10), Grain yield per hill (59.72), Panicle length (24.65) and Plant height (34.50) indicating that simple selection could be effective for improving these characters. Correlation results shown that grain yield per hill exhibited highly and significantly correlation with biological yield and Number of spikelets per panicle. The results of the Path coefficient analysis revealed that both phenotypic and genotypic levels, had positive direct effects on grain yield while compare with parameters like Biological yield, Harvest index %, Number of panicles per hill and Days to 50% flowering. Quality characters i.e., hulling (%), cooking and eating characters i.e., kernel length and breadth before and after cooking, elongation ratio was taken for 19 genotypes. As per mean performance highest maximum grain length was observed in Kasturi, DRRH2, highest elongation ratio observed in MTU - 1121 and NLR - 40024.

Some Agronomical and Physiological Characteristics of Sang Yod Phatthalung Rice from In Vitro Regenerated Plant After Transfer to Clay Soil in Field Conditions

Sang Yod Phatthalung rice is indica rice and grown as Geographical Indications (GI) in Patthalung province. Its dark red color seed contains high antioxidant activity that helps reduction in the risk of some chronic diseases such as diabetes, cancer, and cardiovascular diseases. So far, yield per planting area of this rice is still low. Thus, application of PGRs might play an alternative role in agronomical and physiological characteristics leading to improving yield of this rice. First, shoot tips of Sang Yod Phatthalung rice were cultured to induce multiple shoots and root on liquified PGR-free oil palm culture medium (OPCM) with different concentrations of 6-benzyladenine (BA) (0, 0.5, 1, 1.5 mg/L) alone or in combination with 1-naphthaleneacetic acid (NAA) (0 and 0.5 mg/L). Complete plants were acclimatized to field condition at Phatthalung Rice Research Station (PRRS). After acclimatization for 120 and 140 days, some agronomical and physiological characteristics of rice plant obtained from different PGR containing OPCM were statistically compared. A 2×4 factorial design in RCBD with 4 replication was performed. The results were clearly demonstrated that adding BA in the culture medium increase plant height, number of panicles, panicle length and leaf chlorophyll content. Plantlets obtained from in vitro culturing shoot tip on 0.5 mg/L BA containing medium gave the highest results in average plant height at 189.50 cm, number of panicles at 34.00 panicles, panicle length at 32.50 cm and leaf chlorophyll content at 39.65 SPAD unit. The results from this present study indicated the production of new plant types or characteristics for Sang Yod Phatthalung rice for high yield in future. HIGHLIGHTS The effect of concentrations of PGRs, and culture conditions on agronomical and physiological characteristic were evaluated 5 mg/L BA-derived plants germinated in vitro gave higher results than ex vitro in agronomical and physiological characteristic Addition of 0.5 mg/L BA in the medium increases the plant height, number of panicles, panicle length and leaf chlorophyll content 5 mg/L BA-derived plants in vitro gave the highest plant height, number of panicles, panicle length, and leaf chlorophyll content at 189.50 cm, 34.00 panicles, 32.50 cm, and 39.65 SPAD units, respectively GRAPHICAL ABSTRACT

Estimation of Association among the Yield and Yield Attributing Traits in the Segregating Population of Rice

Indirect selection, using correlation coefficients, linear regression coefficients and path analysis, uses a variety of yield determinants that are more heritable than yield itself and less influenced by environmental factors and therefore are stable. Therefore, indirect selection based on the characters makes the selection process more efficient, especially in the early generations. Correlation coefficient analysis and the use of path coefficients are particularly important for economical and complex traits such as yield, where direct selection is less effective. Thus the present experiment was undertaken to decipher the character association between the characters in a segregating population (F2) obtained from a cross between Naveen x IR 64 Drt1rom the study, it was evident that the characters like leaf breadth, leaf area, plant height, panicle length, number of primary branches, number of secondary branches, number of filled grains, grain length and test weight had the maximum association with yield among the characters under the study. Correlation coefficient and path coefficient analysis, revealed that the characters viz., number of filled grains per plant followed bygrain breadth, total number of grains, number of secondary branches, plant height, number of panicles, leaf breadth, flag leaf area, 1000 seed weight, panicle lengthand number of primary branches had a highly significant and positive correlation with yield and positive direct effect on yield. Thus, emphasis may be given to these traits for the effective selection of promising lines under study.

Yield Component Compensation as Affected by Seeding Rates in Dry Direct Seeded Rice

Sustainability of the transplanted and flooded rice system is threatened by water and labor availability in many Asian countries including the Philippines. Dry direct seeding instead of transplanting is evolving as a viable crop establishment option to deal with labor and water shortages. Two experiments from July 2020 to June 2021 were conducted to determine the effect of different seeding rates [20 kg ha-1 (SR20), 40 kg ha-1 (SR40), 60 kg ha-1 (SR60), and 120 kg ha-1 (SR120)] on the growth, grain yield, and yield components of 2 rice varieties that were established through direct seeding in dry tilled soil and subsequently grown under flooded conditions. Seeding rates of SR40, SR60, and SR120 produced comparable and not significantly different grain yields. However, these seeding rates produced significantly higher grain yields than SR20 (20 kg ha-1). The lower grain yield in SR20 was due to lower panicle density which caused a reduction in sink size. Strong compensation between the number of panicles and the number of grains per panicle was observed in different seeding rates in both varieties. Plants grown at the high seeding rate (120 kg ha-1) had a higher number of panicles but with lower filled grains per panicle. On the other hand, plants grown at the low seeding rate (20 kg ha-1) had more filled grains per panicle with a lower number of panicles per m2. Yield component compensation to maintain desirable sink size was effective at 40 and 60 kg ha-1 seeding rates, although not enough at 20 kg ha-1. Moreover, a longer duration of tiller production was observed at the low seeding rate (SR20) which resulted in a higher number of late emergent tillers with poor grain production. The seed rate of 120 kg ha-1 in this study did not result in yield reduction due to an excessive number of tillers that eventually reduced the number of grains per panicle as observed in other studies. Compensation was between panicle number and grain number per panicle. SR40 and SR60 had similar yield levels with SR120 due to compensation among yield components, these seeding rates would be more attractive to farmers due to lower seed costs.

Growth and result performance of 10 promising resistant lines of tungro disease in Lanrang South Sulawesi

Increased rice production is constrained by various limiting factors, One of these is tungro disease, which can limit productivity. When resistant tungro varieties are available, they are regarded as an affective control tool that is also more environmental friendly. Advanced yield experiment represents a phase in the process of producing cultivars that are resistant to tungro disease. The study aimed to determine the growth and result performance of tungro-resistant lines with greater phenotypic characteristics and yield potential compared to other tungro resistant varieties. The study was carried out from July to October 2018 at the Tungro Disease Research Station in Lanrang Sidrap, utilizing a design with a randomized complete block design, It was repeated three times using 10 tungro-resistant lines and two comparative varieties, namely Inpari 7, Lanrang, and Ciherang. The F test was used to examine the data, and the Least Significant Difference (LSD) test was used to determine significance. The parameters observed were Flowering age of 50% (days), number of panicles per m2, plant height (cm), density score, the weight of 1000 grains, number of filled and unfilled grains per panicle, moisture content (%), grain yield (kg/ha). Results revealed that there were four lines BP12280-3f-7-Kn-2-1*B-Lrg-1-1-10-9, BP12280-3f-7-Kn-2-1 * B-Lrg-1- 1-10-9, BP12206f-8-3-2 * B-LR-20-4 and BP12280-3f-7-Kn-2-1 * B-Lrg-1- 16-14 with a higher grain yield than Ciherang and Inpari 7 Lanrang, which benefited by 1000 grain weight, the number of grains filled per panicle and flowering age is 50% earlier than the comparison variety.

Selection and evaluation of gene-edited knockout mutants of AtAAP2 and AtCRF4 homologs of rice for agronomic nitrogen use efficiency (ANUE)

Nitrogen (N) is essential for amino acid synthesis in rice production, but its excessive use poses an environmental concern. This research aimed to improve rice agronomic nitrogen use efficiency (ANUE) by knockout (KO) of rice homologs of the two selected genes from Arabidopsis thaliana: AtAAP2, an amino acid permease involved in N transportation in shoots, and AtCRF4, a transcription factor participating in N uptake in roots. The homologs of these genes in rice were identified based on amino acid sequence similarity and knocked out using CRISPR/Cas9 mediated gene editing (GE). The AAP2-KO and CRF4-KO lines were subjected to agronomic evaluations with three N doses: 100% (180 kg ha-1), 50% (90 kg ha-1), and 0% (0 kg ha-1) and showed a 130-175% increase in dry biomass weight and a 183-313% increase in panicle number compared to wild type (WT) in the first experiment. These lines also had slower leaf senescence, the so-called “stay-green” trait, indicating the KO effect of target genes in N metabolism. However, neither AAP2-KO nor CRF4-KO showed better yield or ANUE than WT. This study demonstrated the usefulness of GE technology in gene evaluation and highlighted the effects of AtAAP2 and AtCRF4 genes in the plant N cycle.

Water Deficit at Vegetative Stage Induces Tolerance to High Temperature during Anthesis in Rice.

Crop yields have been affected by many different biotic and abiotic factors. Generally, plants experience more than one stress during their life cycle, and plants can tolerate multiple stresses and develop cross-tolerance. The expected rise in atmospheric CO2 concentration ([CO2]) can contribute to cross-tolerance. Priming is a strategy to increase yield or to maintain yield under stress conditions. Thus, our objective was to evaluate if priming the rice plants with water deficit during the vegetative stage can induce tolerance to heat stress at anthesis and to evaluate the contribution of e[CO2]. The experiment was arranged in a completely randomized design in a factorial arrangement. Factor A consisted of the following treatments: water deficit at four-leaf stage (no-stress, and drought stress), heat at anthesis (normal temperature, high temperature), and priming with water deficit at four-leaf stage and heat stress at anthesis; and Factor B was two [CO2] treatments: a[CO2] = 400 ± 40 μmol mol-1 and e[CO2] = 700 ± 40 μmol mol-1. We assessed the effect of the treatments on plant growth, yield, biochemical, and transcriptome alterations. Although e[CO2] affected rice growth parameters, it did not affect the priming effect. Primed plants showed an increase in yield and number of panicles per plant. Primed plants showed upregulation of OsHSP16.9A, OsHSP70.1, and OsHSP70.6. These results showed induced cross-tolerance. Water deficit at the rice vegetative stage reduces the effect of heat stress at the reproductive stage. Water deficit at the vegetative stage can be used, after further testing in field conditions, to reduce the effect of heat stress during flowering in rice.

Effect of Water Stress Duration on the Growth Characteristics and Yield Components of Upland Rice Varieties in Kenya

Drought stress is a major problem in upland rice grown areas under rainfed conditions. It affects plant growth and development, and eventually leads to a considerable yield reduction. The study was carried out with the aim of evaluating the effect of drought stress duration on the growth characteristics and yield components of upland rice varieties. The experiment was conducted at the University of Eldoret with Sixteen upland commercial and local rice varieties were used in the study obtained from Kenya and Liberia. Rice plants were subjected to drought stress treatments at tillering and flowering stages in the green house. The experiment was layout in a complete randomized design (CRD) in a split plot arrangement with five treatments and replicated three times. The results of leaf rolling, plant height, days to 50% flowering, days to maturity, panicle number, spikelet sterility, biological yield, leaf relative water content,1000-grain weight, harvest index and grain yield revealed that there were significant differences as a result of water stress on the treatments (p≤0.001) and rice varieties (p≤0.05). All the sixteen varieties were significantly affected by the treatments when compared with the control. The results also revealed that MWUR, Dourado, L-22, Komboka, Jaowo, LAC-23, Kpatawee, MWUR, White rice and Red Youmo varieties were significantly affected by the water stress treatments at leaf rolling, flowering and maturity then that of NERICA 1,2 ,3, 4, 10,11 and 14 at tillering and flowering stages. The findings of this study indicated that NERICA 1, 2, 3, 4, 10 varieties were less affected by soil water stress treatments amongst the tested varieties, followed by NERICA 11 and14 respectively. Thus, NERICA varieties had the best performance in most of the parameters that were measured. Therefore, these varieties can thus be used by breeders to develop varieties adapted to areas with limited rain fall and insufficient soil moisture for rice production.

Effects of a Novel Weeding and Fertilization Scheme on Yield and Quality of Rice

This study aimed to assess the feasibility of a novel weeding and fertilization scheme, namely, mechanical weeding plus a one-time deep application of a reduced amount of slow-release fertilizer for rice cultivation. The effects of the weeding and fertilization method on rice yield and quality were investigated using a split plot test as the research method. Two weeding methods, namely, chemical weeding (CW) and mechanical weeding (MW), and four fertilization methods were tested, including the conventional fertilization method (quantitative split broadcast application of fast-release N fertilizer (CK)), the quantitative split broadcast application of 80% fast-release N fertilizer (LCK), the one-time base application of slow-release fertilizer (SR), and the one-time deep application of 80% slow-release fertilizer (LSR). The results showed that the rice yield under MW with LSR treatment can maintain a high level—higher than 9.2 t ha−1 per year. This was attributed to the slow-release fertilizer and deep fertilization, which increased the number of stems and tillers in the pre-fertility and spike rate, respectively, resulting in a high panicle number with a 20% reduction of N fertilizer. Furthermore, mechanical weeding improved the seed-setting rate, resulting in a higher number of grains per panicle, a higher panicle number, and an increased thousand-grain weight, thereby maintaining a high yield. At the same time, the quality of rice under MW with LSR treatment improved, specifically reflected in the significant improvement of the processing and appearance quality of rice, a slight increase in protein content, and a reduction in the amylose content, thereby improving its nutritional quality while maintaining good cooking quality.