Productivity and nitrogen use efficiency of rice under conventional and organic nutrition

The current study demonstrates the influence of conventional and organic nutrient management practices on nitrogen use efficiency, growth, yield, and physiological and biochemical parameters in four rice varieties, namely, Jaiva, Ezhome 2, Jyothi and Uma. Growth parameters, grain yield per hill, and physiological and biochemical parameters were higher under conventional management for all rice varieties. Although the nitrogen use efficiency of each variety varied significantly with nutrient management practices, the variation was least in Jaiva (23.8%), which is the organic rice variety released by Kerala Agricultural University. The rice varieties Jaiva and Ezhome 2 showed consistency in the grain weight per panicle under both conventional (Jaiva- 4.57 g, Ezhome 2- 5.86 g) and organic (Jaiva, 4.24 g, Ezhome 2, 4.54 g) management. The soil nitrogen content at the tillering stage (0.66**) showed a significantly higher positive correlation with nitrogen use efficiency under organic management. The results of the study provide a better understanding of factors that can lead to a sustained yield in organic rice production in terms of nitrogen use efficiency

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Not AvailableA field experiment was conducted at the Cropping Systems Research Centre, Karamana, Kerala to assess the adaptability and water productivity of aerobic rice system in the lowlands of southern Kerala. The water productivity of four rice varieties [PTB 52 (Aiswarya), MO 16 (Uma), MAS 946 - 1 (Sharada) and PMK (R) 3] were studied under two moisture regimes – aerobic (30 per cent depletion of available soil moisture) and flooded conditions. The experiment was laid out in randomized block design, with five replications, under both the moisture regimes. Aerobic rice recorded higher water productivity (0.68 kg m - 3) than the conventional flooded rice (0.42 kg m - 3). The variety, MAS 946 - 1 recorded the highest water productivity of 0.60 kg m - 3. Among the four varieties tested, MAS 946 - 1, the first aerobic rice variety released from UAS, Bengaluru and the KAU rice varieties Aiswarya and Uma, proved superior for aerobic conditions in southern Kerala.Not Availabl

Tuberisation Pattern of Tannia (Xanthosoma sagittifolium (L.) Schott) in Response to Crop Management Practices in the South Central Laterites (AEU 9) of Kerala, India

The study was conducted to outline the rooting and tuberisation pattern of tannia (Xanthosoma sagittifolium (L.) Schott) as influenced by different crop management practices. As an underutilised crop, it was uncertain as to the management techniques which would increase tuberisation and productivity levels of tannia. Hence the study was to promote tuberisation in tannia with a focus on the underground portions of the plant. The variation in rooting pattern was studied in terms of root number, root weight and root volume and the tuberisation pattern as number of cormels per plant, corm weight per plant, cormel weight per plant and rate of tuber bulking. The study was conducted in Kollam district under AEU (Agro Ecological Unit) 9 during the period from Feb 2021- Dec 2021. The experiment comprised three treatments in completely randomised design with six replications. The treatments were t1 - KAU POP (Kerala Agricultural University Package of Practices Recommendations), t2 - farmers’ practice and t3 - absolute control. The results revealed that, the root number (43.29), root weight (32.74 g plant-1) and the root volume (38.22 g plant-1) were significantly the highest in t1 (KAU POP) at harvest followed by farmers’ practice and absolute control. When considering the percentage increase in root production, KAU POP recorded 19.22 per cent, 8.79 per cent, 11.04 per cent and 15.66 per cent more number of roots at 4 MAP, 6 MAP, 8 MAP and harvest than farmers’ practice. The number of cormels per plant (12.16), corm weight per plant (563.16 g), cormel weight per plant (439.16 g) at harvest and the rate of tuber bulking (1.27 kg ha-1 d-1) at 4 to 5 MAP were found to be the highest with t1 followed by t2 and t3

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Not Availablesand culture experiment conducted in sweet potato with five levels each of phosphorus and potassium to induce deficiency symptoms revealed the typical P deficiency symptom as purple and yellow discolouration of leaf lamina followed by leaf abcission in almost all the leaves except in the newly emerged leaves. These symptoms started appearing when P concentration in the leaf tissue was 0.04-0.07 percent. Fishbone symptom was the typical of K deficiency and tuber formation was restricted and these symptoms appeared at a leaf concentration of 0.63 percent.Not Availabl

Growth and Yield of Grain Cowpea (Vigna unguiculata sub sp. cylindrica) in Response to Foliar Nutrition and Graded Levels of Phosphorus and Potassium

Aim: To assess the growth and yield of grain cowpea in response to varied doses of phosphorus (P) and potassium (K) supplemented with foliar application of nano diammonium phosphate (DAP) and potassium salt of active phosphorus (PSAP). Study Design: The field experiment was a factorial experiment, laid out in randomised block design with two levels of P, three levels of K and two sources of foliar nutrition, compared against a control, with three replications. Place and Duration of Study: The study was conducted at the Integrated Farming System Research Station, Karamana, Nedumcaud, Thiruvananthapuram, Kerala, India, during the period from December 2022 to February 2023. Methods: The study utilized PGCP-6 cowpea variety and adopted fertilizer recommendations as per KAU POP (Package of Practices Recommendations of the Kerala Agricultural University). The entire dose of FYM, P and K and half dose of nitrogen (N) were applied as basal dose. The remaining half dose of N was applied at 15 days after sowing (DAS). Additionally, foliar application of nano DAP and PSAP (each @ 0.4 %) was done at 20 DAS and 40 DAS. Results: The results of the study revealed that the treatment combination, p2k1f2 and p2k1f1 had comparable leaf area per plant and leaf area index (LAI) (at 60 DAS). The highest seed yield (1642 kg ha-1) was recorded with p2k1f2. Higher dose of P and K along with foliar application of nano DAP (0.4 % at 20 DAS and 40 DAS) had significant effect on the total DMP and haulm yield. Conclusion: Combined application full dose of N, half dose of P, full dose of K and foliar application of PSAP (0.4 %) at 20 DAS and 40 DAS could be recommended as the best treatment combination for yield enhancement in grain cowpea

Molecular Frameworks of Nitrogen Response in Plants: A Review

Nitrogen is a crucial element for all living organisms especially plants which rely on substantial nitrogen quantities to sustain their growth and productivity. Crop production is greatly influenced by nitrogen consumption efficiency and a significant amount of nitrogen fertilizers is used to increase yield. Approximately half of N fertilizers are not utilized by the crops and are lost to the environment by polluting water sources or by releasing pollutants into the atmosphere. From the rhizosphere, plants absorb nitrogen in the form of nitrate (NO3-), ammonium (NH4+), or organic nitrogen (amino acids and urea). Plants exhibit an array of sensing and adaptive mechanisms to respond to the diverse nitrogen nutrition conditions which include morphological and physiological responses. Two primary systems govern nitrogen uptake in plants: the High-affinity transport system (HATS) and the Low-affinity transport system (LATS). Nitrate transporters fall into two categories, Nitrate Transporter 1 (NRT1) and Nitrate Transporter 2 (NRT2) transporters, Chloride Channel Family (CLC) transporters and Slow Anion Associated Channel Homologs (SLAC/SLAHs). The ammonium transporter family includes Ammonium Transporter 1 (AMT1) and Ammonium Transporter 2 (AMT2) transporters. The uptake of organic nitrogen is facilitated through amino acid and urea uptake and transport systems. In fluctuating environmental conditions, plants employ nitrogen response mechanisms to fine-tune homeostasis. A comprehensive understanding of these regulatory mechanisms holds the potential to yield valuable insights for the development of crops with enhanced nitrogen use efficiency

Application of Chitin Improves Growth, Yield and Secondary Metabolite Production in Turmeric (Curcuma longa L.)

A field experiment was conducted in Trivandrum district during June 2021 to January 2022 to evaluate the effect of chitin on growth, yield and secondary metabolite production in turmeric. Soil application of chitin at 5 g per plant was done at 60 and 180 days after transplanting, while untreated plants served as control. Observations were recorded on effect of chitin on growth, defense enzymes, yield, secondary metabolites and disease incidence. Results of the study confirmed significant enhancement in growth, yield and secondary metabolite production on chitin application compared to the untreated control. Significant increase in shoot weight and rhizome weight was observed at six months after transplanting in response to chitin application. Fresh and dry rhizome yield per plant increased by 60.16% and 65.97% respectively, over the control. The defense enzyme activity and chlorophyll content were significantly higher in plants subjected to chitin application, compared to the control. Chitin treatment enhanced volatile oil and oleoresin content by 1.39 and 1.41 times and curcumin content by 21%, over the control. The results confirmed that chitin is a potent biostimulant that can be used for growth, yield and quality enhancement in turmeric

Assessment of Nutrient Status in the Cassava Growing Tracts of Southern Laterites (Agro Ecological Unit 8), Kerala, India

As part of the study, a survey was conducted to identify the soil fertility constraints of cassava growing tracts of AEU 8, Thiruvananthapuram, which is one of the major cassava growing regions of the State of Kerala in peninsular India. The method of sampling of the survey was random sampling wherein a random sample of size one was taken from each of 50 ha cassava area. Panchayat wise soil samples were collected (77 samples) by geo referenced soil sampling method from major cassava growing areas of the unit. The samples are analyzed for the soil fertility parameters following standard analytical procedures. Results indicated that the soil was very strongly acidic to strongly acidic, normal electrical conductivity, medium organic carbon, medium nitrogen and potassium, high phosphorus, sufficient calcium, sulphur, zinc and copper, deficient magnesium and boron

Impact of Cropping Systems on Soil Organic Carbon Levels and Enzyme Activity

Monocropping makes agriculture more susceptible to the adverse effects of climate change. Resilient agriculture systems that can buffer crops against various agricultural vulnerabilities is the need of the hour. In this context, a study was conducted to assess the impact of various rice based cropping systems on soil health. Aims: To study the effect of different rice based cropping systems on soil enzyme activity and organic carbon. Study Design:  Randomized block design, Replications – 3. Place and Duration of Study: Integrated Farming System Research Station (IFSRS) of Kerala Agricultural University located at Karamana, Thiruvananthapuram, during kharif, rabi and summer seasons of 2019-2020. Methodology: The experiment consists of eleven cropping systems (T1 :  rice - fallow - fallow, T2 :  rice - rice - fallow, T3 : rice - daincha - cowpea, T4 : (rice + daincha) - rice - green gram,  T5 : rice - cassava - amaranthus, T6 : rice - cassava - cowpea, T7 : rice - para grass - fodder cowpea, T8 : rice - fodder cowpea - fodder maize, T9 : rice - okra  - culinary melon, T10 : rice - okra  - yard long bean and T11 : rice - rice – amaranthus). Results: Soil organic carbon and enzyme activities were found highest in the cropping system (rice+daincha) – rice – green gram during kharif. During rabi, soil organic carbon and activity of urease and acid phosphatase were highest in rice- daincha- cowpea while dehydrogenase activity was highest in rice- fodder cowpea – fodder maize.  During summer, rice- okra – yard long bean, rice- cassava- amaranthus and rice- cassava – cowpea recorded the highest urease, acid phosphatase and dehydrogenase activity, respectively. The organic carbon was highest for the sequence rice – okra –culinary melon. The soil organic carbon and enzyme activities were least in rice- fallow-fallow cropping sequence during all the three cropping seasons. Conclusion: Brown manuring, use of leguminous crops and cover crops in the crop sequence instead of leaving the land fallow and addition of organic sources of nutrition increase the soil organic carbon and enzymatic activity of microbes. The increase in soil organic carbon and activity of enzymes in soil owing to crop rotation of rice with arable crops relies on the crop species which are cultivated