**3.6 Double transplanted rice**

Double transplanting is a crop establishment system in which rice seedlings are transplanted twice, first on secondary nursery and then in the main field [35]. In this method, seeds are first sown in the primary nursery and subsequently after *Recent Advances in Crop Establishment Methods in Rice-Wheat Cropping System: A Review DOI: http://dx.doi.org/10.5772/intechopen.98743*


#### **Table 2.**

*A study showing mean effect of tillage types on grain yield and economic return of rice.*

3 to 4 weeks, rice seedlings from secondary nursery are again uprooted and transplanted in the main field [36]. In situations where the main field is not ready for transplanting at appropriate time due to late onset of monsoon or continuous stagnation of flood water, double transplanting is advantageous producing healthy and taller seedlings that can easily overcome the adverse situation like high water depth at the time of transplanting [37, 38]. Satapathy *et al*., [35] reported that double transplanting resulted in higher net returns and benefit–cost ratio than normal transplanting which is owing to higher grain yield. Kumar *et al*. [39] also reported higher B-C ratio of 1.99 in double transplanting as compared to single transplanting with a B-C ratio of 1.27. However, this method is quite labor intensive due to the involvement of a second stage nursery and transplanting without proper skill from smaller to larger polybags could give rise to severe transplanting shock. This system is suitable for long duration rice varieties in shallow low land areas.

#### **3.7 System of rice intensification**

System of Rice Intensification (SRI) is one of most revolutionary method of rice establishment which is being adopted in many countries. It consistently outperforms conventional practices providing new possibilities for food security and poverty reduction [40]. The four main principles of SRI are early, quick and healthy plant establishment, reduced plant density, improved soil conditions through enrichment with organic matter, reduced and controlled water application. Unlike conventional method, in SRI, seedlings are transplanted at 2 leaf and 3rdphyllocron stage [41] at 8–12 days age under square planting. Latif and Abdullah [42] reported that the use of irrigation water was reduced by 52.7% in comparison to transplanted rice. In 2002, at the first international conference on SRI, 15 countries reported that the average yield of rice was twice the current average with the use of this system of rice cultivation [43]. Kumar et al. [44] reported higher grain yield and total water productivity of rice grown in SRI method as compared to normal transplanting method. Hossain *et al*. [45] also reported a handsome grain yield of 7.62 t/ha in SRI as compared to 6.59 t/ha in traditional method. SRI is generally suitable for areas where the soil is fertile, fine textured, well drained and maintenance of alternate wetting and drying conditions is possible. However, high labour requirement and problems faced at the time of transplanting of young seedlings are some of the constraints of this method.

#### **4. Recent advances in crop establishment methods of wheat**

The main constraint faced by wheat crop in the rice-wheat cropping system is delayed planting leading to terminal heat stress due to growing of long duration rice varieties and the time required for land preparation after harvesting of the submerged rice crop. The crop establishment practices mentioned below are devised to manage those problems.
