Root Growth, Nutrient Uptake and Yield of Medicinal Rice Njavara Under Different Establishment Techniques and Nutrient Sources

Field experiments with medicinal rice Njavara were conducted at Cropping Systems

Rice is an important crop and will continue to play a vital role in food security for millions of people in India. The future of Indian food security and foreign exchange through rice exports will also largely depend on desired production and productivity. Opportunities are great for attaining high yield in rice through proper agronomic management practices, low cost mechanization in seeding, weeding and suitable establishment techniques (Budhar, 2011). Njavara is widely used in the Ayurvedic system of medicine, especially in Panchakarma treatment. Njavara as a special cereal, has the properties to rectify the basic ills affecting our circulatory, respiratory and the digestive systems.
The water and nutrient uptake ability of plants highly depends on the root architecture (Lynch, 1995), while the root system directly affects the amount of water available to crop. Most of crops largely rely on stored water in the soil profile. The root systems of rice consist of seminal and nodal roots with first-and higher-order lateral roots. The roots length can penetrate from 70 to 80 cm in soil. However, the lowland rice has got a shallow and compact root system, most of which are distributed in the top 15 cm of soil (Morita et al, 1995). The soil moisture has a profound impact on root growth, viability and functionality and thus plant growth (Huang, 1999). The deep extensive root enhances 1*Corresponding author email: malarrani@rediffmail.com water utilization in the deeper soil profile, which is considered to be an important trait of drought resistance in plants. Keeping all the above in view, the present investigation was undertaken to study the developmental phenology of Njavara root growth and its nutrient uptake under different establishment techniques and nutrient sources.

Materials and Methods
Field experiments were conducted for two consecutive years i.e., summer/third crop/puncha season of 2007 and 2008 at Cropping systems research centre, Karamana, Thiruvananthapuram, Kerala. The soil was acidic in reaction (5.5 pH), high in organic carbon content (1.23%), medium in available nitrogen (261.9 kg ha-1), available phosphorus (22.0 kg ha-1) and available potassium (140.2 kg ha-1) status. The experiments were laid out in a split plot design with three replications by fitting the establishment techniues in main plot viz. SRI (System of Rice Intensification) (M1), ICM (Integrated Crop Establishment Method) (M2), PoP (Package of Practices) (M3) (Recommendation of Kerala Agricultural University) as well as the Conventional Management Practices (M4) and nutrient sources viz., organic sources (S 1), integrated nutrient sources (S2) and inorganic sources (S3) in sub plot. Eight, twelve and eighteen days old seedlings as per treatments were transplanted at the rate of 1, 2 and 3 seedlings per hill at 20x20 cm, 20x20 cm and 15x10 cm spacings in SRI, ICM and PoP treatments, respectively. In conventional management practices, pre germinated seeds were broadcasted on the same day. Nutrient management recommendation of Package of Practices: Crops KAU (2007) of Kerala Agricultural University was adopted i.e 5t FYM + 40:20:20 kg NPK ha-1. Full FYM + 2/3 N + Full P + ½ K were applied as basal. 1/3 N + ½ K were applied at panicle initiation. In the organic treatments 40:20:20 kg NPK ha-1were supplied through FYM, rock phosphate and wood ash. In integrated nutrient management treatments, 40: 20: 20 kg NPK ha-1 were supplied through urea, rock phosphate and muriate of potash along with 5t FYM. In the inorganic treatments, NPK contribution by 5t FYM was calculated and they were supplied through urea, rock phosphate and muriate of potash. NPK was also applied at the rate of 40:20:20 kg ha-1, respectively.

Effect of rice establishment techniques and nutrient source on root dry matter production
Root dry matter production in Njavara was significantly influenced by rice establishment techniques. Root dry matter hill-1 was recorded at weekly interval from 4th WAT/WAS till physiological maturity. At the early stages (4-6 WAT/WAS) root dry matter production hill-1 was in the order SRI >ICM > conventional management practices > PoP 487 which changed to SRI > ICM > PoP > conventional management practices from 7th week onwards (Table  1). Throughout the crop growth period, all the establishment techniques differed significantly from one another in root dry matter hill-1. Increase in root dry matter occurred up to 9 WAS/WAT (Weeks after transplanting/Weeks after sowing). Higher root dry matter (at 9th WAS/WAT) was recorded in SRI Increase in root dry matter in SRI and ICM may be attributed to increased aeration in soil due to stirring of soil by rotary weeder. Rotary weeder was operated four times in SRI treatments and two times in ICM treatments. Till 6th week, root dry matter production in conventional management practices was higher than that in PoP which may be attributed to the earlier establishment and root development in the broadcast crop. But from 7th week onwards root development occurred at faster rate in PoP compared to conventional management practices which might be due to availability of more space for individual hill under transplanted condition. This would have reduced the competition for nutrients and water. Planting of single seedling rather than in clumps helped to avoid root competition and promoted vigorous root growth (Uphoff and In square planting with wider spacing, more soil area was available for foraging leading to improved root characters viz., root length, root volume and root dry weight resulting in more photosynthetic activity. This might be reason for higher root and straw dry matter in SRI. Similar result was reported by Shrirame et al., (2008).

Effect of rice establishment techniques and nutrient source on nutrient uptake
Nutrient uptake by grain, straw and total uptake by crop showed more or less the same trend in both the years. The total nutrient uptake (N, K, Fe, Mn and Zn) were in the order CMP > PoP > SRI > ICM. Total P uptake was in the order CMP > SRI > PoP > ICM.  all nutrients in PoP and ICM were on par and that in SRI and ICM were also on par. Nabheerong (1992) reported that total nutrient uptake in broadcast seeded flooded rice was higher than that in transplanted rice due to transplant shock, lower plant density and higher N losses in transplanted rice.
Nutrient sources showed significant influence on total uptake by the crop (P, K, Fe and Zn) in both the years. Nutrient sources showed no significant influence on total N, S and Mn uptake. Highest P uptake (1.82/1.89 kg ha -1 in 2007/2008), K uptake (24.11/26.38 kg ha -1 in 2007/208), Fe uptake  Ayalew and Dejene (2012) stated that integrated nutrient management is the best approach to supply adequate and balanced nutrients and increase crop productivity in an efficient and environmentally benign manner, without sacrificing soil productivity of future generations. Mithun et al., (2007) and Srinivasan and Angayarkanni, (2008) reported that uptake of nutrients was improved by the application of integrated use of organic and inorganic fertilizer compared to RDF.

Effect of rice establishment techniques and nutrient source on yield
Higher grain yield recorded in conventional management practices (M4)  respectively. Significantly higher grain yield realized in conventional management practices may be attributed to the significantly better growth and yield parameters realized in this treatment compared to other establishment techniques. Significantly higher growth characters like leaf number per plant, leaf area index and tiller number per unit area might have resulted in increased photosynthesis and production of photosynthates which finally transformed into significantly higher number of panicles per unit area and higher relative accumulation of dry matter in the panicles. Straw yield also showed the same trend like grain yield in establishment techniques and nutrient sources.

Conclusion
Even though Njavara did not respond to SRI and ICM to the same extent in tillering like other varieties, all the tillers produced in SRI were productive tillers and 91% of the tillers produced in ICM bore panicles. Uptake of all the nutrients in conventional management practices was significantly higher than that in the other three establishment techniques.

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Highest total nutrient (P, K, Fe and Zn) uptake by crop (grain + straw) occurred in integrated nutrient source. Maximum root dry matter (at 9th WAS/WAT) was recorded in SRI and root development was least in conventional management practices which combined with least culm strength might have resulted in lodging of the crop. Tiller per unit area in SRI practices was found to be the minimum which limit the uptake of nutrients, where in case of conventional management practices it found to be wise versa.