Putt. A.K. and Urmila Pathania. Regional Research Laboratory, Jammu-Tawi, Jammu and Kashmir, India.1. EFFECTS OF NITROGEN AND PHOSPHORUS ON SEEDLING GROWTH AND NODULATION IN LEUCAENAEffects of nitrogen and phosphorus separately and in combination on seedling growth and nodulation in leucaena were studied in three different polypot experiments. The first experiment on the effect of nitrogen was studied with three doses of urea (0, 1, and 2.5 g per seedling). The second experiment on the effect of phosphorus involved four levels of single superphosphate (SSP)(0, 1, 2.5, and 5 g per seedling). The third experiment examined the combined effect of nitrogen and phosphorus with three doses (0, 1, and 2.5 g/seedling) of diammonium phosphate (DAP). In each experiment, ten seedlings were used per treatment and each treatment was replicated six times. Treatment effects were recorded after 60 days of growth in the first two experiments and after 75 days in the third experiment (Table 1).Table 1. Effects of nitrogen and phosphorus (separately and in

combination).Treatment Seedling Dry wt/

height seedlingDry wt stem/

seedlingDry wt root/

seedlingNodules/seedling

Fresh wt nodules/ seedling

-cm- - g - - g - - g - -mg-Nitrogen as ureaLevel of urea (gm)

0 56.93 3.02 2.35 0.67 12.5 0.05071 56 .34 2.77 2.26 0.51 - -2.5 - - -

Phosphorus as single superphosphate (SSP)Level of SSP (gm)

0 32.20 1.05 0.80 0.25 12.1 0.03041 53 .01** 2.32** 1.88** 0.44* 12.9 0.03442.5 58.72** 2.83** 2.31** 0.52* 1.7 0.00145 60.35** 2.10 1.72* 0.38 -

LSD @ 5% 12.11 1.10 0.72 0.17Combined nitrogen and phosphorus as di-ammonium phosphate (DAP)Level of DAP (gm)

0 65.77 3.41 2.79 0.62 57 .7 0.17961 75.03 4.64* 3.91* 0.73 -2.5 53.74 2.43 2.03 0.40 - -

LSD @ 5% 12.83 1.17 0.47 0.15"

* Significant ** Highly significantUse of 1 gm urea/seedling retarded seedling growth and completely suppressed nodulation. The higher dose of 2.5 gm urea/seedling proved lethal as not a single seedling could survive this high dose.

In the second experiment, 1 g SSP/seedling increased growth and nodulation. Seedling height increased by 65%; the dry weight of seedling by 121%; the dry weight of stem/seedling by 135%; the dry weight of root/seedling by 76%; the number of nodules per seedling by 7%, and the fresh weight of nodules/seedling increased by 13% over control. Statistically, the increase in seedling height was highly significant over the control and the increase in dry weight of seedling, dry weight of stem/seedling and dry weight of root/seedling were significant over the control. With 2.5 gm SSP, seedling growth was enhanced, but nodule forma­tion was suppressed. With 5 gm SSP, only seedling height was marginally increased but other growth factors were retarded and nodule formation was completely suppressed.In the third experiment, 1 gm DAP/seedling increased seedling growth but completely suppressed nodulation. With 2.5 gm DAP, seedling growth was retarded and nodulation was completely suppressed.2. EFFECTS OF DIFFERENT NUTRIENTS ON THE GROWTH OF LEUCAENAEffects of different nutrients on the growth of Leucaena leucocephala var. K8 were studied in two separate field experiments.2a. Effast ot phosphorus and micro nutrientsThe first experiment on the effect of phosphorus and micro­nutrients involved three treatment combinations replicated seven times in a randomized block design with 25 trees grown in each plot at a spacing of 1 m x 1 m. The three treatment combinations were:

T1 - ControlT2 - Soil application of 50 gm single superphosphate per

treeT3 - Soil application of 50 gm single superphosphate mixed

with 200 mg each of cobalt chloride, ammonium molybdate, zinc sulphate, copper sulphate, manganese sulphate and 500 mg sodium borate per tree

The nutrients were applied in the planting holes at the time of transplanting the 3-month-old saplings. Treatment effects, in terms of heights and breast height diameters of trees, were recorded after the trees were 15 and 36 months old, and the tree volumes were calculated (Table 2).Differences in heights, breast height diameters and volumes of the trees between T1 and T2 were not significant at 15 months.At 36 months, differences in heights were highly significant, but breast height diameters and volumes of the trees did not differ significantly from each other. Between Tl and T3, the differences in heights, breast height diameters and volumes of the trees were significant at 15 months and highly significant at 36 months. At 15 months, the increases in heights, breast height diameters and volumes of the trees in T3 were 13%, 18% and 52% over the control (Tl), and at 36 months the increases were 18%,29% and 73% over the control.

Table 2. Effect of phosphorus and other nutrients.Treatments Hgt

15-mo 3 6-moDbh

15-mo 3 6-moVol.

15-mo(m3/ha) 3 6-mo

-m- -cm- -m3/ha-T1 5.1 7.5 3.1 4.7 24.9 95.9T2 5.2 8.3** 3.2 5.5 28.2 128.0T3 5.78 8.9** 3.6* 6.1** 37 .8* 166.3**C.D. at 5% 0.46 0.55 0.43 0.77 8.90 36.11C.D. at 1% 0.64 0.77 0.60 1.07 12.48 50.62* Significant ** Highly significant

2b. Effect of nitrogen - phosphorus complex and micronutrientsThe second experiment was on the combined effect of nitrogen and phosphorus and micronutrients, with five treatment combinations replicated five times in a randomized block design with 16 trees grown in each plot at a spacing of 1.5 m x 2.0 m. The five treatment combinations were:

T1 - ControlT2 - Soil application of 25 gm di-ammonium phosphate per treeT3 - Soil application of 25 gm di-ammonium phosphate mixed with 100 mg ammonium molybdate, 200 mg cobalt chloride and 500 mg sodium borate per tree

T4 - Soil application of double the dose of all nutrients of T3 per treeT5 - Soil application of all nutrients of T4 mixed with 400 mg each of copper sulphate, zinc sulphate and manganese sulphate per tree

The nutrients were applied in planting holes when the 3-month- old saplings were transplanted. Heights and breast height diameters of trees were recorded after the trees reached the ages of 21 and 36 months age, and the tree volumes were calculated (Table 3).Table 3. Effect of nitrogen-phosphorus complex and other

nutrients.Treatments Hgt.

21-mo 36-moDbh.

21-mo 36-moVol.

21-mo 36-mo-m- -cm- -m3/ha-

T1 6.5 8.0 4.6 5.8 22.7 45.9T2 6.5 8.1 4.8 6.3 26.3 54.6T3 6.6 8.1 4.9 6 .3 26.5 53.8T4 6.6 8.0 4.9** 6.4 27.0 56.6T5 6 .8 8.4 5.4** 7.0** 33.0* 69.4*C.D. at 5% 0.6 0.7 0.5 0.8 8 .0 17.2C.D. at 1% 0.9 1.0 0.7 1.1 11.0 23.8* Significant ** Highly significant

The data revealed gradual increases in heights, breast height diameters and volumes of the trees from T1 to T5 both at 21 and 36 months. The differences in height increases between treat­ments were not significant at either stages of growth, although the difference in breast height diameter of trees between T1 and T5 were highly significant at both stages. Likewise, difference in volume of trees between T1 and T5 at both stages were also significant. However, between T2, T3, T4 and T5 the difference either in breast height diameter or in volume were not significant at either stages of growth. At 21 months, the increase in heights, breast height diameters and volumes of the trees in T5 were 5%, 17% and 45% over the control T1. At 36 months, the respective increase were 5%, 20% and 51% over the control.The results indicate that using phosphorus along with other nutrients is more beneficial to the growth of leucaena than the use of nitrogen-phosphorus complex and other nutrients.