The experiment was conducted in Agroforestry and Environment Research Field of HSTU. There were five treatment combinations of crop residues including control in both the experiments. These extracts were applied in the Ghora neem seedlings. The CRD design was followed with five replications in each treatment. These were: T1 = Pineapple leaf extracts, T2 = Napier grass extracts, T3 = Wheat plant extracts, T4 = Maize plant extracts and T5 = Water (control). Four crop-residue extracts were selected for the study viz. pineapple leaf extract, napier grass extracts, wheat plant and maize plant. For preparing crop extracts, 1 kg fresh crop leaves with twigs were blended in blender machine mixing with two litre water. Then the mixture was boiled for about 1 hour until the extracts reduce to 1 litre. After that the extracts were cooled and filtered. After filtering the extract was preserved in containers for further use.
For germination test, 20 seeds of Ghora neem were taken in each treatment and sown in the germination tray. The trays were then placed in the open condition. After 7 days of seed sowing, four different crop extracts were started to apply. Every week crop extracts were applied up to 9 weeks. Germination data were collected on the germination percentage, germination speed, shoot number and days of germination initiation etc. Germination speed was calculated as under (Chiapusio et al. 1997): S= (N1*1) + (N2–N1)*1/2 + (N3- N2)*1/3 + … + (Nn- Nn-1) *1/n.
Where, N1, N2, N3, …… Nn-1, Nn refers to the proportion of germinated seeds on the 30th , 33rd, 36th days, …, n-1, n days. The inhibitory / stimulatory effects of extracts on test crops were expressed in percentage (%) of control and were calculated according to T/C, where T is the “treatment” data and C is the “control” data.
For growth trial, naturally grown Ghora neem seedlings were collected under the Ghora neem tree and transplanted in the polybags of the size 9” x 6”. The age of the seedlings was 2 months during the time of seedling collection. After transplantation, the polybags were placed in the open field. After one week of transplantation, residue extracts were started to apply in all treatments. There were 12 seedlings for each treatment in the field. Crop residue extracts were applied 15 days interval in all the treatments. The morphology of shoot and roots and their biomass were measured in four times. Above ground parameters that were measured are seedling height (cm), root collar diameter (mm), length of central roots, number of living branches. Above ground parameters that were measured are shoot dry weight (g), root dry weight and total dry biomass.
For biomass measurement, the seedlings were divided into two parts: shoot and root system. The root systems were separated from the soil through gentle wash of water using a bucket and sieve to collect any root fragments detached from the system. Branches and leaves were mixed together to get the shoot weight. Both parts were oven-dried at 80°C (Royo et al. 2001; Tsakaldimi et al. 2009) for 72 hours until they reached in a constant weight. They were weighed through an electric balance to get shoot dry weight (g), root weight (g). Then total oven dry weight (g) was calculated. The root to shoot ratio was calculated by the root and shoot dry weights (Thompson, 1985). The seedling quality index (QI) was calculated using the equation (Dickson et al. 1960): QI=total seedling dry weight (g)/[height (cm)/diameter (mm)+shoot dry weight (g)/root dry weight (g)].
For biomass measurement, the seedlings were divided into two parts: shoot and root system. The root systems were separated from the soil through gentle wash of water using a bucket and sieve to collect any root fragments detached from the system. Branches and leaves were mixed together to get the shoot weight. Both parts were oven-dried at 80°C (Royo et al. 2001; Tsakaldimi et al. 2009) for 72 hours until they reached in a constant weight. They were weighed through an electric balance to get shoot dry weight (g), root weight (g). Then total oven dry weight (g) was calculated. The root to shoot ratio was calculated by the root and shoot dry weights (Thompson, 1985). The seedling quality index (QI) was calculated using the equation (Dickson et al. 1960): QI=total seedling dry weight (g)/[height (cm)/diameter (mm)+shoot dry weight (g)/root dry weight (g)].