Seedling Characteristics and the Early Growth of Transplanted Rice Under Different Water Regimes

Abstract

A series of experiments was conducted on rice seedlings in a nursery seedbed and after transplanting in order to understand root and shoot characteristics, and their contribution to the production of tillers and dry matter. At the nursery stage, the seedlings' were studied at varying densities (high and low) and fertilizer treatments (with and without nitrogen) at 12 and 24 days after sowing (DAS) in wet or dry seedbeds. After transplanting, the effects of seedling age at the time of transplanting (12 and 30 days), method of raising seedlings (dry or wet seedbed) and water regimes (flooded or non-flooded) were studied. The overall aim was to understand the benefits, if any, of this system of rice intensification (SRI) management practices over conventional methods. The study revealed that in a nursery at 12 DAS, rice seedlings raised in a dry seedbed, irrespective of seeding density and fertilizer application, showed accelerated growth with better shoot and root characteristics in terms of greater leaf number, plant height, lateral root formation and elongation, and dry mass compared to seedlings grown in a wet seedbed. At 24 DAS, a significant interaction between seeding density and fertilizer application was found for dry-seedbed plants compared to those grown in a wet seedbed. Poor shoot and root growth was seen in older seedlings grown without fertilizer. Seedling age was found to be the most important factor affecting both shoot characteristics after transplanting (number of tillers, plant height, dry matter production) and root characteristics (root length density, root weight density). Younger seedlings performed better than older seedlings transplanted into either flooded or non-flooded soils with greater uptake of nitrogen and manganese than older seedlings. These results indicate that many of the constraints previously associated with non-flooded rice cultivation may be alleviated by transplanting younger seedlings that have been raised by SRI methods.

Impact of Rice Nursery Nutrient Management, Seeding Density and Seedling Age on Yield and Yield Attributes

“…The positive effect of low seeding density and fertilizer top dressing is of course due to less competition and better plant nutrition, and older seedlings seemed to provide an additional advantage in the drier 2009 season. We did not see a strong effect of fertilizer management in contrast to Mishra and Salokhe, who observed that fertilizer application in the nursery was a crucial factor in increasing seedling vigor [31]. Similarly Farooq et al also found an increasing trend of plant height after transplanting improved nursery seedlings [32].…”

Towards an understanding of the high productivity of rice with System of Rice Intensification (SRI) management from the perspectives of soil and plant physiological processes

“…A shallow depth for Figure 1 Diagrammatic representations of the developmental changes in rice nursling seedlings and the ideal plant ages of nursling seedlings for transplantation (Sasaki 2004). transplanting nursling seedlings could also be favorable for more tillering. Also, biological potential of rice seedlings and their improvement in an oxic nursery environment are suggested for young seedlings (12d old) even they are transplanted to flooded paddy field (Mishra and Salokhe 2008).…”

“…Moreover, the high nitrate content was maintained for more than one month after transplanting and showed the translocation of NO 3 into new roots in the field. Mishra and Salokhe (2008) examined the effect of different water regimes before and after transplanting and showed that nursery water management affected the rate of development after transplanting. They also showed that a dry seedbed was better than a wet seedbed, as the former helps to shorten the phyllochron (period of leaf emergence) and helps produce seedlings with better rooting.…”

Evaluating the Optimum Transplanting Time for Different Coarse Rice Genotypes under Semi-Arid Conditions of Faisalabad

“…Pakistan earned US$ 1.53 billion in rice exports and it contributes 3.2% in the value addition in agriculture and 0.7% of GDP [7]. Every day increasing urbanization and population in cities and villages increases the demand and consumption of rice worldwide [8].…”