Abstract: In order to study the effects of seedling age and planting spaces on yield and yield components of rice (Neda Variety) a field experiment was carried out in field of Ghaemshahr Azad University. Experimental design was arranged in split plot in basis of Randomized Completely Block design with four replication. Some agronomical traits such as total tiller number, fertile tiller number, panicle number per m2, total spikelet per panicle, total strile spikelet per panicle, 1000 grains weight and grain yield were measured. Results showed that the effect of seedling age on total tiller number and panicle number per m2 was significant at 0.01 probability level. Also seedling age had a significant effect on fertile tiller number at 0.05 probability levels. Planting spaces had a significant effect on total tiller, fertile tiller, panicle per m2, total spikelet per panicle and grain yield. when the age of seedling is less than optimum, the tender seedlings may die in greater number due to high temperature and ultimately the plant population is reduced. For this variety transplanting in seedling age at 25 day and 15x15 cm planting space for the best performance of yield attributes were recommended.
INTRODUCTION
Rice is the most important crop at the global level, as it used as a staple food in the most countries of the world (Dowling et al., 1998). Rice is the principle food crop of Iran feeding almost hundred percent of its population. Rice scientists are engaged in developing new high yielding varieties and management practices to increase the productivity per unit land area per unit time. Achieving a sustainable increase in rice production can improve global food security and contribute to poverty alleviation. The reason for such low yield mainly associated with cultural technologies. Among cultural technology application of best planting space is the important ones (Barari, 2005). The growth of rice plant is greatly affected both qualitatively and quantitatively by planting density (Hoseini, 2004). Transplanting of healthy seedlings of optimum age ensures better rice yield. When seedling are transplanted at right time, tillering and growth proceed normally. However when seedling stay longer in seed nursery bed, primary tiller buds on the lower nodes of the main culm often degenerate. Primary tiller buds of 4th to 7th nodes are held inside when seedling are planted at 7th leaf age (Matsuo and Hoshikawa, 1993). Age of seedling at the time of transplanting is an important factor for uniform stand establishment of rice (Paddalia, 1981). On the other hand, if the age of seedlings is more than optimum, the seedlings produce less tillers due to reduce vegetative period and thereby results in poor yield. Thus, to improve yield and quality of fine rice, optimum age of seedling for transplanting needs investigations. Selection of suitable planting density and seedling age are the most important factors for maximizing rice production.
MATERIALS AND METHODS
The experiment was conducted at field of Ghaemshahr Azad University in north of Iran. This experiment was laid out in split plot in basis of Randomized Completely Block design with four replications. The plot size was 15 m2. main factor was seedling age in three levels (25, 35, 45 day) and minor factor was planting space (including 15x15 cm, 20x20 cm, 25x25 cm, 30x30 cm). All plots received 100 kg P2O5 ha-1 and 100 kg K2O ha-1 before transplanting. The nitrogen fertilizer in the form of urea was applied at the rate of 132 kg N ha-1 in two split doses. Half of nitrogen fertilizer was applied before transplanting while the remaining quantity applied as top dressing in the maximum tillering stage, standards cultural practices were carried out until the plant was matured. Four hills (excluding border hills) were randomly selected from each plot for measuring total tiller number. Six hills (excluding border hills) were randomly selected from each plot prior to harvest for measure yield components. Grain yield was determined from harvest area of 6 m2 adjusting to 14% moisture content. All statistical tests were done using the Statically Analysis System (SAS, Institute, 1996) and mean values were compared by Duncan Multiple Range Test (DMRT).
RESULTS AND DISCUSSION
Effect of seedling age: The seedling age had a significant effect on total tiller number and panicle number per m2 at 0.01 probability level also seedling age had significant effect on fertile tiller number at 0.05 probability level (Table 1). The highest tiller number (18.67), highest fertile tiller number (17.55) and highest panicle number per m2 (354.6) were obtained in seedling age at 45 day (Table 2). Seeding age had not significant effect on total spikelet per panicle, sterile spikelet per panicle, 1000 grains weight and grain yield. These findings are in conformity with those of Shahani et al. (1984), Chandra and Manna (1988), Ali and Rahman (1992) and Paul (1994), who stated that the seedling age had non significant effect on grain yield. The highest spikelet number per panicle (171.6) was obtained in 25 day seedling age. The highest grain yield (1018 g m-2) was obtained in transplanting at 35 day seedling age. Alam et al. (2002) showed that the least tiller number was produced in seedling age at 21 day. In this research the least total tiller number was obtained in seedling age at 25 day.
Effect of planting space: Planting spaces had significant effect on
total tiller number, fertile tiller number, panicle number per m2,
total spikelet per panicle and grain yield at 0.01 probability level. The highest
tiller number (23.5), fertile tiller number (22.49) were obtained at 30x30 cm
planting spaces.
| Table 1: | Mean squares of agronomical traits of Neda variety |
| Ê = Seedling age x Planting space, ns = Non significant, *, ** significant at 0.05 and 0.01 probability level | |
| Table 2: | Mean comparision of agronomical traits of Neda variety |
| Means with similar letter(s) in each column are not significantly different at the 0.05 probability level according to Duncan,s Multiple Rang Test | |
| Table 3: | Interaction effect of seedling age and planting spaces on agronomical traits of Neda variety |
| Means with similar letter(s) in each column are not significantly different at the 0.05 probability level according to Duncan,s Multiple Rang Test | |
The greatest panicle number per m2 (427.3) and the highest grain yield were obtained in 15x15 cm planting space. Barari (2005) got almost the similar results which showed that in low planting spaces, grain yield was increased. Total spikelet per panicle (178.6) was produced at 25x25 cm planting space. The least grain yield was obtained at 30x30 cm planting space. Planting spaces had not significant effect on sterile spikelet number and 1000 grains weight. Paul et al. (2002) reported that high density reduced total tiller number per hill but fertile tiller number was improved by high density. Between 30, 45, 60 and 75 day seedling age, the highest grain yield was obtained at 45 day seedling age and increase in seedling case reduce in grain yield (Table 2).
Interaction of seedling age and planting space: The highest grain yield (1149 g m-2) was observed in first seedling age in case of 15x15 cm planting space. The least grain yield (860 g m-2) was produced in third seedling age with 30x30 cm planting space (Table 3).
ACKNOWLEDGMENT
Financial support by the Faculty of Agriculture, Ghaemshahr Azad University and Mashhad Azad University highly appreciated.