Basmati Rice Varieties Research Articles

Evaluation of Basmati Rice (Oryza sativa L.) Genotypes for Seedling Growth and Leaf Physiology Under High‐Temperature Stress

ABSTRACTRice, a staple food crop for over half of the global population, is facing a serious threat of rising temperature due to climate change, especially in the areas producing Basmati rice. The main objectives of the study were to compare the promising cultivars of Basmati rice for heat stress tolerance and to assess how elevated temperature affects leaf physiological and morphological parameters of fine rice at seedling stage. A 2‐year‐controlled pot experiment was carried out to evaluate how different Basmati rice varieties respond to heat stress. The experiment was carried out at the Agronomic research area, University of Agriculture Faisalabad, Pakistan, during 2022 and 2023. The design of experiment was completely randomised design (CRD) with split treatment structure and four replications. Plant morphology, leaf temperature, chlorophyll contents, relative cell injury and relative water contents were evaluated for both experimental years. Heat stress significantly affected all morphological and physiological attributes such as chlorophyll contents, relative water contents and relative cell injury across different varieties. There was variation in the behaviour of different varieties under stress conditions as compared to no heat, but from the results it was very clear that Kisan Basmati and PK‐1121 Aromatic constantly showed poor performance under both conditions for all the recorded parameters. However, in almost each parameter evaluated, Basmati‐515, Super Basmati and NIAB‐16 exhibited Superior thermo tolerance and better performance. On the basis of observed morphological and physiological attributes, Kisan and PK‐1121 Aromatic Basmati were graded as sensitive varieties, while Basmati‐515, Super Basmati and NIAB‐16 showed tolerance to heat stress as compared to other varieties. However, further research is needed to explore the underlying mechanisms and genetic factors contributing to the sensitivity or tolerance observed in these varieties.

Nitrogen regimes affect agro-physiology, carbon assimilation and sink behavior of scented rice

Agro-physiology, C-assimilation & its contribution in sink development; and crop yield can be augmented through N regimes for higher productivity of scented rice (aromatic and basmati). Being scented rice sink limited crop; we loomed to enhance sink capacity by augmenting leaf area index (LAI) though nitrogen (N) regimes in new environment. In order to establish N-relationship with sink capacity (SC) & filling efficiency (SFE) and to determine N-related agro-physiological behavior a field experiment for two years conducted in middle IGP. Four N levels (control, low, moderate and high) tested for two aromatic and two basmati rice varieties under split plot design. The basmati rice varieties reported 37.81-52.13% higher grain yield (GY) with lesser N over short grained aromatic varieties. Dry matter, its translocation and pre-anthesis contribution, tiller number and physiological traits at growth stages were also comparatively higher in HUBR 10–9 over short grained HUR 917 and comprehended parity level with HUR 4–3. The SFE was negatively correlated with SC and LAI across nitrogen dose and varieties. Higher LAI at moderate N produced larger sink; higher SFE was at low N. On contrary to short grained HUR 917; BS varieties (HUBR 10–9 & HUBR 2–1) produced larger sink. Economic N was lower for BSV’s (126.48–131.52 kg N ha−1) with GY potential of 5.11–6.01 Mg ha−1.

Development of a Technology Valuation Model for Commercial Licensing: An Empirical Case of PB 1718 Basmati Rice Variety

Development of a Technology Valuation Model for Commercial Licensing: An Empirical Case of PB 1718 Basmati Rice Variety

Identification of a Promising Novel Genetic Source for Rice Root-Knot Nematode Resistance through Markers Associated with Trait-Specific Quantitative Trait Loci.

Direct-seeded rice (DSR) is gaining popularity among farmers due to its environmentally safe and resource-efficient production system. However, managing the rice root-knot nematode (RRKN), Meloidogyne graminicola, remains a major challenge in DSR cultivation. Developing genetic resistance is a pragmatic and effective approach compared to using hazardous pesticides. Pusa Basmati 1121 (PB1121) is the most popular Basmati rice variety, but it is highly susceptible to RRKN. In contrast, Phule Radha (PR) has shown highly resistant reaction to RRKN, as reported in our earlier study. We generated an F2:3 population from the cross of PB1121/PR and evaluated it for RRKN resistance-related traits under artificial inoculation conditions. The distribution pattern of traits in the F2:3 population indicated that resistance may be governed by a few major-effect genes and many minor-effect genes. The molecular markers reported to be associated with QTLs governing RRKN resistance traits were used to test in the current population. Although the simple linear regression identified significant associations between the markers and RRKN resistance-associated traits, these associations were spurious as the LOD score was below the threshold limit. This indicates that PR possesses novel genomic regions for resistance to RRKN as it does not possess any of the earlier reported QTLs.

SONA SUPER BASMATI: A NEW EXTRA-LONG GRAIN HIGH YIELDING RICE VARIETY WITH EXCELLENT COOKING QUALITY

Abstract Rice crop feeds about half of the world’s population which is getting larger and hungrier with every tick of the clock. Basmati rice being a geographical speciality of Pakistan is widely proclaimed as one of the finest rice available throughout the world due to its unique aroma, taste, and texture. Changing consumer behavior and preferences for basmati rice i.e., extra-long grain length along with excellent cooking quality, reiterates the revitalization of rice breeding objectives to develop suitable basmati rice varieties. In this context, plant breeders at Rice Research Institute, Kala Shah Kaku identified a suitable transgressive segregant from F2 segregating population of a cross (PK 10436) between the famous basmati rice variety “Basmati 515” (female parent) and 99417 (male parent). The initial cross of PK 10436-4-2 was accomplished during Kharif, 2010 followed by its rigorous selection and purification in succeeding generations through the pedigree method till F4 generation in Kharif, 2014. After its development, PK 10436-4-2 was evaluated in Station Yield Trials (Kharif, 2016 - 2019) for various yields and its attributing traits in which it gave a cumulative 31.37 % yield advantage over the check variety (Super Basmati). Meanwhile, multi-locational yield evaluation was accomplished in Micro-plot Yield Trials and National Uniform Yield Trials for two consecutive years (Kharif, 2020 - 2021) at various locations across Pakistan; in which, PK 10436-4-2 out-yielded the check variety by 17.50 % and 19.75 % respectively. In addition to superior yield indices, PK 10436-4-2 showed excellent cooking quality i.e., extra-long grain length (AGL = 9.5 mm; CGL = 17.5 mm), with strong aroma. The aforementioned superior credentials of this candidate line led to its approval for general cultivation as “Sona Super Basmati” in the 56th meeting of the Punjab Seed Council, Punjab, Pakistan. In the future, prospects of cultivating Sona Super Basmati could create new vistas not only in local rice consumption but also in the basmati rice export of Pakistan.

Classification of Rice Grain Varieties Using Ensemble Learning and Image Analysis Techniques

This research explored the efficacy of machine learning techniques, specifically the Bagging meta-estimator, in the classification of rice grain images. Utilizing a dataset composed of 45,000 images of Arborio, Basmati, and Jasmine rice varieties, a 5-fold cross-validation was employed to evaluate the model's performance. The results were highly promising, with the model consistently achieving over 96% in accuracy, precision, recall, and F1-score across all folds, indicating its robustness and reliability. The study confirmed that ensemble learning techniques could significantly improve the classification accuracy over single classifier systems in agricultural applications. The findings offer a significant contribution to automated agricultural processes, suggesting that machine learning can greatly enhance the efficiency and precision of rice variety classification. These results pave the way for further research into the integration of such models into agricultural quality control and provide a foundation for the exploration of advanced image processing and deep learning techniques for improved performance. Future research directions include expanding the model to encompass a wider variety of crops and integrating additional data modalities to refine classification accuracy further. Practical applications should explore the incorporation of this technology into existing agricultural systems to maximize the benefits of automation in quality control.

Effect of nitrogen levels and green manuring on grain and straw yield in Basmati rice varieties

Effect of nitrogen levels and green manuring on grain and straw yield in Basmati rice varieties

Effect of tillage methods and sowing dates on growth, yield and yield attributes of newly released Basmati rice (Oryza sativa L.) varieties under direct seeded

To standardize the tillage methods and dates of direct seeded Jammu Basmati rice varieties under sub tropical condition, a field experiment was conducted at research farm of Agrometeorology Section, Division of Agronomy, SKUAST-J, Chatha, Jammu during kharif season 2020. The experiment was comprised of two tillage methods i.e. zero (T1) and conventional tillage (T2) , two direct sowing dates viz., 10th (D1) and 25th June (D2) along with four newly released Basmati rice varieties viz., Jammu Basmati-370 (V1), Jammu Basmati-118 (V2), Jammu Basmati-138 (V3) and Jammu Basmati-123 (V4) with 16 treatment combinations and three replications in split-split plot design. Various crop growth parameters (plant height, LAI and above ground dry matter accumulation) were recorded at fortnight interval starting from 30 DAS till physiological maturity of crop was attained. Jammu Basmati rice varieties sown under conventional tillage method recorded significantly higher number of tillers/m2 (232.7) and also effective tillers/m2 (222.7) than the zero tillage method. The 10th June sown crop observed significantly higher leaf area index, dry matter accumulation, yield and yield attributes compared to late sown crop. Crop sown under conventional tillage method realized significantly higher grain yield (23.74 q/ha) as compared to zero tillage method (18.03 q/ha). Among the varieties, Jammu Basmati-123 recorded significantly higher leaf area index, dry matter accumulation and grain yield followed by Jammu Basmati-118, Basmati-370 and Jammu Basmati-138.

KNOWLEDGE AND ADOPTION LEVEL OF FARMERS WITH RESPECT TO PACKAGE OF PRACTICES OF BASMATI RICE CULTIVATION

The present study was conducted to find out the knowledge level of basmati rice growers in Shahjahanpur district of Uttar Pradesh. The data was collected through personal interview schedule from the basmati rice growers for the investigation based on their knowledge of package of practices in basmati rice cultivation. The study reported that majority (77.50%) of basmati rice growers were having high knowledge about land preparation, (65.00%) use of green manuring, (56.66%) basmati rice growers were having high knowledge of harvesting of basmati rice and the majority (84.17%) basmati rice growers were having medium knowledge about transplanting and (81.66%) selection of improved basmati rice varieties for basmati rice cultivation. The study also reported that the majority (77.50%) of rice growers were having low knowledge about soil treatment and (45.83%) use of balanced fertilizers in basmati rice cultivation. The study further reported that the majority (87.50%) of the basmati rice growers were fully using sandy loam and loamy soil for basmati rice cultivation and the majority (87.50%) of the basmati rice growers were fully adopted proper field preparation practices for basmati rice cultivation in the study area. The study also reported that the majority (80.83%) of the basmati rice growers were fully adopted harvesting time of basmati rice.

Genetic Enhancement for Biotic Stress Resistance in Basmati Rice through Marker-Assisted Backcross Breeding.

Pusa Basmati 1509 (PB1509) is one of the major foreign-exchange-earning varieties of Basmati rice; it is semi-dwarf and early maturing with exceptional cooking quality and strong aroma. However, it is highly susceptible to various biotic stresses including bacterial blight and blast. Therefore, bacterial blight resistance genes, namely, xa13 + Xa21 and Xa38, and fungal blast resistance genes Pi9 + Pib and Pita were incorporated into the genetic background of recurrent parent (RP) PB1509 using donor parents, namely, Pusa Basmati 1718 (PB1718), Pusa 1927 (P1927), Pusa 1929 (P1929) and Tetep, respectively. Foreground selection was carried out with respective gene-linked markers, stringent phenotypic selection for recurrent parent phenotype, early generation background selection with Simple sequence repeat (SSR) markers, and background analysis at advanced generations with Rice Pan Genome Array comprising 80K SNPs. This has led to the development of Near isogenic lines (NILs), namely, Pusa 3037, Pusa 3054, Pusa 3060 and Pusa 3066 carrying genes xa13 + Xa21, Xa38, Pi9 + Pib and Pita with genomic similarity of 98.25%, 98.92%, 97.38% and 97.69%, respectively, as compared to the RP. Based on GGE-biplot analysis, Pusa 3037-1-44-3-164-20-249-2 carrying xa13 + Xa21, Pusa 3054-2-47-7-166-24-261-3 carrying Xa38, Pusa 3060-3-55-17-157-4-124-1 carrying Pi9 + Pib, and Pusa 3066-4-56-20-159-8-174-1 carrying Pita were identified to be relatively stable and better-performing individuals in the tested environments. Intercrossing between the best BC3F1s has led to the generation of Pusa 3122 (xa13 + Xa21 + Xa38), Pusa 3124 (Xa38 + Pi9 + Pib) and Pusa 3123 (Pi9 + Pib + Pita) with agronomy, grain and cooking quality parameters at par with PB1509. Cultivation of such improved varieties will help farmers reduce the cost of cultivation with decreased pesticide use and improve productivity with ensured safety to consumers.

Susceptibility of different Basmati rice varieties to bakanae disease and it’s integrated management in rice cultivar Pusa Basmati 1121

Susceptibility of different Basmati rice varieties to bakanae disease and it’s integrated management in rice cultivar Pusa Basmati 1121

Effect of ethyl methanesulfonate mediated mutation for enhancing morpho-physio-biochemical and yield contributing traits of fragrant rice.

Chemical mutagenesis has been successfully used for increasing genetic diversity in crop plants. More than 800 novel mutant types of rice (Oryza sativa L.) have been developed through the successful application of numerous mutagenic agents. Among a wide variety of chemical mutagens, ethyl-methane-sulfonate (EMS) is the alkylating agent that is most commonly employed in crop plants because it frequently induces nucleotide substitutions as detected in numerous genomes. In this study, seeds of the widely consumed Basmati rice variety (Super Basmati, Oryza sativa L.) were treated with EMS at concentrations of 0.25%, 0.50%, 0.75%, 1.0%, and 1.25% to broaden its narrow genetic base. Sensitivity to a chemical mutagen such as ethyl methanesulfonate (EMS) was determined in the M1 generation. Results in M1 generation revealed that as the levels of applied EMS increased, there was a significant reduction in the germination percent, root length, shoot length, plant height, productive tillers, panicle length, sterile spikelet, total spikelet, and fertility percent as compared to the control under field conditions. All the aforementioned parameters decreased but there was an increase in EMS mutagens in an approximately linear fashion. Furthermore, there was no germination at 1.25% of EMS treatment for seed germination. A 50% germination was recorded between 0.50% and 0.75% EMS treatments. After germination, the subsequent parameters, viz. root length and shoot length had LD50 between 05.0% and 0.75% EMS dose levels. Significant variation was noticed in the photosynthetic and water related attributes of fragrant rice. The linear increase in the enzymatic attributes was noticed by the EMS mediated treatments. After the establishment of the plants in the M1 generation in the field, it was observed that LD50 for fertility percentage was at EMS 1.0% level, for the rice variety. Hence, it is concluded that for creating genetic variability in the rice variety (Super Basmati), EMS doses from 0.5% to 0.75% are the most efficient, and effective.

The potential use of Indian rice flour or husk in fortification of pan bread: assessing bread's quality using sensory, physicochemical, and chemometric methods.

Hassawi rice is an Indica variety cultivated in Saudi Arabia with a higher nutritional value than the commercial Basmati rice varieties. The present study has investigated the feasibility of combining Hassawi rice flour (HRF) or husk (HRHF), an abundant byproduct, with wheat flour to produce nutritious economical pan bread. To achieve this aim, the physicochemical properties of HRF and HRHF were assessed using techniques such as UPLC-tandem MS, ICP-OES, and colorimeter. The proximate composition (moisture, crude fiber, and ash) and mineral contents of HRHF are significantly (p < 0.05) higher than HRF. On the other hand, the compounds p-coumaric acid, vanillic acid, γ- and δ-tocotrienols, and γ-oryzanol were unique to HRF. We further determined the changes in sensory, technological, and physicochemical properties of wheat flour bread substituted with 5%, 10%, and 15% of HRF or HRHF. The rheological tests showed that the addition of HRF and HRHF increased dough development and stability time. Further, substituting wheat flour for HRF and HRHF at levels higher than 10% affected sensory attributes, such as color, taste, odor, flavor, and appearance. These changes, however, were not always at a significant level. The causes of the differences in properties between control and fortified bread samples were investigated by chemometric methods. Samples of bread HRF at 5 and 10% had comparable overall profiles to the control. On the other hand, bread HRHF samples proved to retain higher concentrations of bioactive molecules compared to the control bread. Our findings shed light on the possible use of rice husk fibers in baking goods, notably pan bread. Furthermore, by integrating rice husk fibers into baked goods, we may boost their health benefits while also contributing to the long-term use of agricultural waste.

Detection of fumonisin among different strains of Fusarium spp. associated with bakanae disease of rice (Oryza sativa L.) using molecular markers

Bakanae disease caused by Fusarium fujikuroi of basmati rice causes huge economic losses varying with varieties produced, with a frequency of 3.0-95.4%. The Fusarium spp. associated with bakanae disease produce fumonisins, a group of structurally similar sphingosine analogue mycotoxins, among which Fumonisin B1 is the most prevalent and active (FB1). The worst harm to both people and animal wellbeing is created by fumonisins, which infect feed and food sources. IARC, a global organization dedicated to cancer research, classified FB1 as a potential causing human cancer (Group 2B). Altogether 26 strains of Fusarium spp. from bakanae infected samples of various popular basmati rice varieties collected from Hisar, Jind, Fatehabad, Bhiwani, Sirsa, Panipat, Sonipat, Karnal, Yamunanagar, Kaithal and Kurukshetra (eleven) districts of Haryana state. Two specific primers namely VERTF and polyketide synthase (PKS) (involved in fumonisin biosynthesis) FUM (rp 32 and rp 33) were utilized in this investigation to differentiation between fumonisin-producing and non-producing strains employing PCR technique. Twenty-two strains were significant for the VERTF primer and showed the capacity to generate fumonisin, while four isolates evaluated negative for both primers. The FUM specific primer displayed positive respose only in nine strains and rest were negative. The present study provides a rapid and specific method that helped in accurate differentiation between fumonisin-producing and non-producing strains.

Effect of prohexadione-calcium onphotosynthetic and yield parameters in basmati rice (Oryza sativa L.) against lodging stress

Basmati rice cultivators with longer internodes and shallow rooting system are prone to lodging especially during panicle development thus ultimately reducing yield, quality as well as efficiency of mechanical harvesting.Manipulation of GA status both via using exogenous application of GA or use of GA biosynthesis inhibitors or either by genetic alteration are regularly used to optimize plant growth and yields. Keeping this in mind the main objective of the study was to assess the role of Prohexadione-calcium (Pro-Ca) to reduce internode elongation against lodging stress without negatively affecting its productivity. A field experiment was conducted on three cultivars of basmati rice (Punjab Basmati 2, Punjab Basmati 3 and Pusa Basmati 1121) in split plot design at three concentration levels (foliar application) of Pro-Ca @5,10 and 20mg/l at vegetative and anthesis stage. Pro-Ca was found to uphill the concentrations of total chlorophyll (~9%)and Carotenoid(~4%) content in leaves at both vegetative and anthesis stages. An increment in the photosynthetic rate in flag leaf was also recorded in Pro-Ca treated sets in comparison to control, A significant increase in sucrose content in fully expanded leaf at vegetative and flag leaf at anthesis stage was recorded.Plant height significantly decreased in Pro-Ca treated plants and this decrease in height was recorded more with increased concentration of Pro-Ca. The increase in the yield contributing parameters viz., number of spikes/plant and grain/m2might be attributed to the blockage of gibberellins synthesis on account of Pro-Ca applicationin selected basmati rice variety PUSA 1121 by upregulating the photosynthetic rate (2%) andalso increase in sucrose content(2 to 18%).

Aroma component analysis using HS/SPME-FID Gas Chromatograph in Basmati rice varieties of Punjab, Pakistan

Rice grain aroma is a promising quality factor that influence consumer acceptability. The principal volatile compound that contributes Basmati rice fragrance is 2-acetyl-1-pyrroline (2AP). Milled White rice samples of promising Basmati rice varieties (Super Basmati, Basmati-515, Basmati 2000, Basmati 370) were analyzed for fragrant volatile compounds by gas chromatography (GC) coupled with Solid Phase Micro Extraction unit (SPME) using Flame ionizing Detector (FID). Six volatile compounds (Nonanal, Decanal, and alcohols such as benzyl alcohol, Indole) were identified in the tested varieties, among them 2-AP is only present in aromatic rice varieties. This study confirmed the occurrence of 2-AP in all studied varieties with highest concentration in Super Basmati followed by Basmati-515, Basmati 2000 and Basmati 370.

Novel quantitative trait loci for yield and yield related traits identified in Basmati rice (Oryza sativa)

AbstractIncreasing crop productivity is one of the prime goals of crop breeding research. Rice grain yield is a complex quantitative trait governed by polygenes. Although several QTLs governing grain yield traits have been reported and limited attempts have been made to map QTLs for grain yield parameters in Basmati rice. A population from the cross Sonasal and Pusa Basmati 1121 comprising 352 RILs was generated through the single seed descent method. A total of 12 QTLs governing yield and yield‐related traits were mapped on six chromosomes, namely, 1, 2, 3, 7, 8 and 9, of which five QTLs were novel. We identified a novel and robust epistatic QTL (qPH1.1 and qPL1.1) governing plant height and panicle length, flanked by the markers RM5336‐RM1 on chromosome 1. The gene encoding brassinosteroid insensitive 1‐associated receptor kinase 1 precursor is the putative candidate gene underlying this epistatic QTL. Another novel QTL, qNT3.1, governing tiller number was bracketed to a region of .77 Mb between the markers RM15247 and RM15281 on chromosome 3. Of the 57 annotated gene models, Os03g0437600 encoding alpha/beta‐fold hydrolase, a homologous to AtKai2 is a putative candidate gene underlying the novel QTL qNT3.1. The other QTLs such as qDFF1.1 governing days to 50% flowering co‐localizes with the gene Ghd7, QTL for plant height qPH1.2 co‐localizes with the gene sd1, the QTLs for panicle length co‐localizes with FUWA and DEP2, the QTL for tiller number co‐localizes with OsRLCK57 and QTLs for thousand‐grain weight co‐localize with the major gene GS3. The QTLs identified in the current study can be effectively used in marker‐assisted selection for developing Basmati rice varieties with a higher yield.

Seed biopriming with potential bioagents influences physiological processes and plant defense enzymes to ameliorate sheath blight induced yield loss in rice (Oryza sativa L.).

Disease management with the use of conventional pesticides has emerged as a major threat to the environment and human health. Moreover, the increasing cost of pesticides and their use in staple crops such as rice is not economically sustainable. The present study utilized a combination of two commercial powder formulations of biocontrol agents, Trichoderma harzianum (Th38) and Pseudomonas fluorescens (Pf28) to induce resistance against sheath blight disease via seed biopriming in basmati rice variety Vasumati and compared the performance with systemic fungicide carbendazim. Sheath blight infection significantly increased the levels of stress indicators such as proline (0.8 to 4.25 folds), hydrogen peroxide (0.89 to 1.61 folds), and lipid peroxidation (2.4 to 2.6 folds) in the infected tissues as compared to the healthy control. On the contrary, biopriming with biocontrol formulation (BCF) significantly reduced the level of stress markers, and substantially enhanced the levels of defense enzymes such as peroxidase (1.04 to 1.18 folds), phenylalanine ammonia lyase (1.02 to 1.17 folds), lipoxygenase (1.2 to 1.6 folds), and total phenolics (74% to 83%) as compared to the infected control. Besides, improved photosynthesis (48% to 59%) and nitrate reductase activity (21% to 42%) showed a positive effect on yield and biomass, which compensated disease induced losses in bio-primed plants. Conversely, the comparative analysis of the efficacy levels of BCF with carbendazim revealed BCF as a potential and eco-friendly alternative for reducing disease impact and maintaining higher yield in rice under sheath blight infection.

Introgression of Drought Tolerance into Elite Basmati Rice Variety through Marker-Assisted Backcrossing

Drought is one of the major abiotic threat to rice production in the context of climate change. Super Basmati is an elite, fine grain basmati rice variety grown in Punjab, Pakistan. Due to drought sensitive in nature, its yield has been facing an alarming situation in production because of gradual decrease in irrigated water for a couple of years. Three reported novel QTLs for drought tolerance were selected for incorporation into Super Basmati by employing marker assisted selection strategy. IR55419-04 with novel QTLs was used as a donor parent. Foreground selection was performed by applying PCR based QTL linked SSR markers followed by recombinant selection by using 2–4 flanking markers. Background selection was exercised by using polymorphic SSR markers for maximum genome recovery of the Super Basmati. The individuals homozygous at the target QTLs and with maximum background of Super Basmati at the rest of the non-target genome was selected for evaluation of drought tolerance. Under drought stress conditions, the yields of all introgressed lines (ILs) were 44.2%–125.7% higher than recurrent parent. Six superior ILs that are drought tolerant and very similar to Super Basmati in terms of agronomic and grain quality traits are marked for release as drought-tolerant varieties in arid regions or for use in breeding programs of high grain quality and drought-tolerant parents.

Site-Specific Fertilizer Nitrogen Management in Less and High N Responsive Basmati Rice Varieties Using Newly Developed PAU-Leaf Colour Chart

ABSTRACT Fertilizer nitrogen (N) management in long-grained aromatic basmati rice (Oryza sativa) is critical because both below and above the optimum N application rate adversely affects yield. Multi-location field studies were conducted in northwestern India to formulate a site-specific N management (SSNM) strategy for basmati rice by monitoring the greenness of the fully expanded top leaf of the crop plants using a leaf color chart (PAU-LCC) specially developed at Punjab Agricultural University, Ludhiana. The green colour intensity of the successive panels of PAU-LCC increases with consistent decrease in optical reflectance by 1.6% (at 550 nm wavelength) and thus provides better precision in quantifying leaf colour greenness over the IRRI-LCC (the LCC developed at International Rice Research Institute, Philippines). The threshold leaf greenness at which a variety will respond to fertilizer N was found to be equal to LCC shade 3.5 and 4.0 for less and high N responsive varieties, respectively. Monitoring leaf greenness using LCC at weekly intervals and application of 10 kg N ha−1 whenever leaf greenness was less than the specified threshold level constituted the appropriate SSNM strategy. The SSNM produced grain yield equivalent to soil-test-based fixed N rates but with 20 to 60% less N fertilizer. Significantly higher agronomic (average 40.8 vs. 24.5 kg grain kg−1 N) and recovery (average 76.1 vs. 52.7%) efficiencies of fertilizer N were recorded with SSNM than with soil-test-based fixed fertilizer N rates. The SSNM also reduced N2O and GHG emissions by 20.1 and 23.6% as compared to soil-test-based fertilizer N rates.