Modern Plant Breeding For Sustainable Agriculture: A Review

More foods are required to fulfill human need. The limitation of the farming area is leading to intensification system in crop cultivation, so the use of chemical properties and environmental destruction cannot be denied. However, this industrial practice in the crop system has caused many adverse effects on ecological balance and human health. Many severe impacts of industrial agriculture practices have been reported, including soil erosion, groundwater contamination, loss of productivity, depletion of fossil resources, air pollution, new threats to human health and safety. Many experts agreed that sustainable agriculture seems to be an effective way to solve these issues. Modern plant breeding is now a popular approach to provide superior crop cultivars that can minimize adverse effects of agriculture practices because humans can recognize and manipulated genes through this method. Recently, the application of molecular markers in plant breeding selection has been brought enthusiasm for plant breeders. Marker-assisted selection (MAS) has been evidenced to be a beneficial technique in plant breeding. Through this approach, the selection process of parents and progenies in the breeding process could be more efficient. Plant breeding is influential in crop production achievement because this effort is connected with the adaptability and stability of the varieties in many different environmental circumstances. Plant breeding also focuses on agriculture sustainability due to its effort to produces durable disease resistance, abiotic stress tolerance, nutrients, and water-use efficiency

Morpho-physiological screenings and molecular analysis of west sumatra rice genotypes under submergence stress

This study investigates the submergence tolerance level of 14 rice genotypes by morpho-physiological and molecular analyses of Sub1 alleles. IR64-Sub1 was used as a submergence tolerant check. The submergence screenings were conducted by submerging 14-days-old seedlings in water tanks for 14 days while molecular analysis was conducted using 14 Sub1 linked markers. The results showed that 5 tested genotypes, namely Inpari 48 Blas, Mundam Putiah, Batang Piaman, Banang Pulau and Pulau Sijunjung, recorded high survival rates (SR) of 80% to 100% under submergence stress. PCR-based identification of the Sub1 alleles confirmed that several tested genotypes carry Sub1A and Sub1C, but not all were expressed in their phenotypic performance towards submergence. IR64-Sub1 and Batang Piaman not only showed well-adaptation towards submergence by maintaining lower elongation (<20%) and less chlorophyll content change (TCC) (<30%) but were also equipped with the Sub1A allele. These genotypes potentially provide good phenotypic and genotypic performance under submergence stress conditions. Additionally, based on population structure analysis, these genotypes were grouped into 3 clusters, of which 35.71% are pure accessions, while the remaining 64.29% have admixture ancestry between populations 1, 2 and 3. The data in model-based population structure and UPGMA dendrogram supported that rice genotypes in this study have 3 well-differentiated genetic populations and admixtures. Most genotypes have a close genetic relationship with Nei’s similarity index ranging from 0.571 to 0.893

Morphological variations of weedy rice (Oryza sativa ssp.) in selected rice fields of Peninsular Malaysia

Weedy rice or locally known as ‘padi angin’ has been infesting rice granary areas in Malaysia for the last 20 years. The outbreak of weedy rice in the country started during the late 1980s in Projek Barat Laut Selangor (PBLS) due to the adoption of direct-seeding practices. Weedy rice can be characterized by its early maturing and easy-shattering traits. The objective of this study was to determine the morphological variations of weedy rice in selected granary areas located in Peninsular Malaysia. A total of 110 weedy rice accessions were collected from nine locations in three granary areas in Peninsular Malaysia (the Western, Eastern, & Northern regions). The collected weedy rice accessions were planted under greenhouse conditions to study their morphological features. Results of the present study indicated that 73.6% of weedy rice accessions were awnless while the remaining 26.4% produced awn. Selected traits such as plant height, flag leaf length, culm length, number of tillers, number of panicles, and panicle length were included in the Principal Component Analysis (PCA). The weedy rice accessions were grouped into three different clusters mainly Cluster 1: cultivated rice and awnless populations, Cluster 2: brown and red pericarp awnless populations, and Cluster 3: awned populations. The findings of this study may be used as guidance for farmers and researchers for designing sustainable weedy rice management in the future

Heat stress in vegetables: impacts and management strategies - a review

Global climate change has not only caused a significant rise in the average temperature around the world but has also threatened crop productivity and food security. Heat stress disrupts various plant physiological and biochemical processes, such as inhibition of growth and development, reduction of photosynthesis rate and nutrient uptake, consequently causing yield losses. The destructive effects of heat stress are expected to worsen in the coming years. Thus, it has become imperative to understand how vegetables respond and adapt to heat stress in order to improve their heat tolerance ability. Various approaches have been adopted to enhance heat stress tolerance in vegetables, including modifying cultural practices and crop improvements through several breeding methods. This review gives comprehensive and up-to-date information on the effects of heat stress on vegetables; and existing as well as emerging methods adopted to enhance heat tolerance in vegetables. It also provides a brief overview of a new method called speed breeding, which can be leveraged to fast-track the breeding process for developing heat stress-tolerant vegetables

Carbon-Ion beam radiosensitivity study and biological responses of high-yieldingrice line, MR219-PL-5

The carbon ion-beam has emerged as a novel physical mutagen for creating genetic variability and crop improvement. In this study, seeds of a high-yielding pyramided rice line MR219-PL-5 were exposed to carbon ion beam irradiation at 10, 20, 40, 60, 80, and 100 Gy. The radiosensitivity test was conducted to determine the optimum dose of carbon ion beam irradiation based on the lethal dose 50% (LD50) using Sandwich Blotter Technique. The biological responses of carbon-ion beam irradiation were also observed in other characteristics such as germination rate (GeR), survival rate (SR), growth rate (GRoR), shoot length (SL), root length (RL), seedling height (SH), days to flowering (DTF), fertility rate (FR) and thousand-grains weight (TGW). Based on the polynomial curve of SR graph, the lethal dose 50% (LD50) value was 86.12 Gy. However, the optimum dose range of carbon ion-beam irradiation was between 40 and 60 Gy as these two doses recorded the highest SR, 63 and 67%, respectively. Furthermore, the shoulder dose in this study was 60 Gy since SR decreased significantly at higher doses. M1 individuals irradiated at 40 and 60 Gy had the best biological responses where significant differences were found for SR, SL, RL, GRoR, SH, DTF and FR at these two doses compared to the other doses. Further studies on M2 and M3 populations could help to identify potential individuals as well as to understand the inheritance of each trait of interest from one generation to the next

Susceptibility of Malaysian Rice (Oryza sativa L.) Cultivar to Saline Water Submergence Based on the Morphological Traits

Saline water submergence is a newly emerge abiotic stress jeopardizing rice production especially for the rice fields located nearby or alongside coastal areas. The stress was caused by the intrusion of sea water into those rice fields causing flash flood mainly during monsoon season. The present study was conducted to evaluate susceptibility level of selected Malaysian rice cultivars to saline water submergence at seedling stage based on the morphological traits and survival rate. There were six genotypes involved in the study mainly IR64-Sub1 as submergence tolerant control, Pokkali as salinity tolerant control, IR64 as susceptible control and MR297, MR284 and MR253 as local rice cultivars, respectively. The experiment was conducted using split plot design with three replications. On the day 14 after germination, all rice seedlings were totally submerged of about one-meter depth in a polyethylene tank containing saline water at 0, 4, 8 and 12 dS/m for 14 days while the non-submerged plant was control of the experiment. Seedling growth attributes and survival rate were recorded before, right after de-submerged and 14 days after de-submerged. All genotypes however were susceptible to saline water submergence at 4, 8 and 12 dS/m. In contrast, under 0 dS/m, IR64-Sub1 recorded significantly higher survival rate at 83% as compared to MR284 (17%), MR297 (17%), Pokkali (8%), MR253 (0%) and IR64 (0%).  All genotypes were not survived under saline submergence. Therefore, further phenotypic screening of rice genetic resources originated from or nearby coastal areas could be suggested in order to increase chance of identifying potentially tolerant genotype to saline water submergence

Drought-induced changes in the flowering capacity, anthesis quality and seed set in rice (Oryza sativa L.)

Drought stress significantly reduces grain yield (GY) due to poor spikelet fertility and anthesis quality. Aim of this study was to understand the changes of flowering capacity, anthesis quality traits and seed set in the re-watered drought stressed modern high yielding drought susceptible rice cultivar, IR64 at heading (DSH) and booting (DSB) stages. The wellwatered plants served as control of the experiment. Results obtained suggest that spikelet moisture content at above 80% was required to maintain optimum anthesis process in rice. Anthesis process in DSH plant was suspended when leaf relative water content (LRWC) dropped to below than 70%. Effects of drought stress on the spikelet moisture were irreversible as compared to the leaf rolling and LRWC. Hence, seed set was failed to occur at the upper rachis branches of the DSH plant. Anthesis process in the re-watered drought stress plants was resumed on the third day after re-watering with about 50% and 80% of anthers managed to dehisce in the DSH and DSB plants. Consequently, percentage of spikelet fertility and seed set in the DSH and DSB plants were increased towards the lower parts of the panicle. The GY, number of seeds, spikelet fertility, and harvest index however were significantly lower in the DSH plant (0.30 g, 13, 16.40%, and 14.81) as compared to DSB plant (1.34 g, 57, 59.14%, and 48.30), respectively. In addition, all interrelated traits involved in the flowering process of rice could be collectively termed as the anthesis quality traits due to their significant correlation with the grain yield and other yield components

Response of primed rice (Oryza sativa L.) seeds towards reproductive stage drought stress

Seed priming could be promoted as a potential alternative in alleviating drought stress challenges in rice cultivation. The present study was conducted as an attempt to verify potential performance of seed priming in improving seedling growth and harvestable grain yield of rice under reproductive stage drought stress (RS). Seed treatments involved were non-primed seeds as control (T1), hydro-primed (T2) and osmo-primed at -1.0 mPa with polyethylene glycol (PEG6000) (T3). Reproductive stage drought stress (RS) was imposed at soil water potential lower than -60 kPa. The well-watered plants served as control of the experiment. In general, seedling growth of T3 was better than T2 and T1 for all growth parameters in both planting seasons. Yield components were significantly lower in RS as compared to well-watered treatment (WW). The agronomic performance of primed seeds in T2 and T3 were not significantly different with T1 under both RS and WW for both planting seasons. As a conclusion, seed priming treatments used in this study was ineffective in improving agronomic performance of rice under RS. Therefore, other alternatives such as development of drought tolerant rice should be highly emphasized in order to minimize the impact of drought on growth and yield of rice plant

Morphological, Biochemical and Genetic Variation of Rice (Oryza sativa L.) Genotypes to Vegetative Stage Salinity Stress

Salinity is one of the most serious issues in rice cultivation and production. Salt stress significantly reduced seedling growth performance of rice. This research was conducted to study the effects of vegetative stage salinity stress on morphological, biochemical, molecular and genetic variation of 12 rice genotypes as well as 2 check varieties, MR297 (susceptible) and Pokkali (tolerant). The experiment was arranged in a split-plot design with 3 replications. Normal freshwater at 0 dS m-1 (L1), saline water at 6 dS m-1 (L2) and saline water at 12 dS m-1 (L3) were the main plot and rice genotypes were the sub-plot. In general, morphological and biochemical traits of all genotypes showed an overall reduction of about 47.41% in L3 as compared to L1 except for the tolerant check, Pokkali. The genetics and correlation analysis indicated that plant height, leaf size and standard evaluation system (SES) score might be used as a selection criterion in developing salt tolerant rice. The multivariate analysis revealed that a Malaysian landraces, Jarom Mas was clustered together with Pokkali as tolerant genotype. Screening using tightly linked Simple Sequence Repeat (SSR) markers (RM1287, RM10748, RM493) of salinity tolerant QTL, Saltol indicated that this QTL was absence in Jarom Mas. This finding might indicate the presence of other QTL associated with salinity tolerance in Jarom Mas. Further study on identifying the speculated QTL may be conducted to confirm this postulation

Penilaian sifat fisio-kimia dan analisis hedonik bagi titisan piramid padi tahan kemarau terpilih

Pembiakbakaan padi tahan kemarau menjadi agenda utama ahli pembiak baka namun ia amatlah penting bagi memastikan kultivar padi baru tahan kemarau yang bakal dihasilkan mampu memenuhi cita rasa pengguna daripada segi ciri fisio-kimia serta kualiti beras dan nasi. Dalam kajian ini, sebanyak sepuluh genotip padi yang terdiri daripada lapan titisan piramid padi tahan kemarau (PLs) dan dua induk, MR219 dan MRQ74 dinilai bagi ciri fisio-kimia dan kualitinya. Kesemua genotip mempunyai kandungan amilosa (AC) yang sederhana iaitu dalam julat 20% hingga 25% kecuali PL-MR219-G1 (AC rendah - 16%) dan induk MRQ74 (AC tinggi - 27%). Selain itu, kesemua genotip juga mempunyai suhu pengelatinan (GT) yang sederhana, konsistensi gel (GC) yang lembut serta mempunyai bentuk beras yang tirus. Tiada perbezaan yang signifikan diperoleh antara PLs dan induk untuk kesemua atribut dalam analisis hedonik kecuali bagi ciri aroma dalam populasi MRQ74. Skor PL-MRQ74-G1 bagi ciri aroma dalam ujian sensori berbeza secara signifikan dengan induk menunjukkan bahawa nasi yang dihasilkan PL ini tidak wangi. Analisis genotip turut mengesahkan gen yang mengawal ciri aroma, alel badh2 tiada dalam PL-MRQ74-G1 disebabkan rekombinasi semasa silangan. Namun demikian, alel badh2 hadir dalam PL-MRQ74-G2 yang menyokong hasil ujian hedonik dan PL ini tidak berbeza dengan MRQ74 bagi atribut aroma. Secara amnya, PLs serupa dengan beras komersial yang merupakan induk mereka bagi ciri fisio-kimia dan kualiti. PLs yang tahan kemarau ini boleh dikomersialkan kerana memenuhi cita rasa pengguna Malaysia yang sukakan nasi yang lembut dan tirus selain tempoh memasak yang singkat