Introduction

Cotton can tolerate water stress until first square formation; however yield is very sensitive to the irrigation regime. But later, during flowering and boll formation, water demand reaches the peak very fast. At that time, crop coefficient for cotton is 1-1.1. When most bolls of the first phase mature, water application can be reduced sharply. Shortage or standing water both are hazardous for the crop in determining its yield and the effects are even more harmful where the irrigation water is saline or of bad quality. Heavy water stress to the cotton crop will induce flower abscission and excess irrigation will initiate vegetative growth that will compete with boll formation. Drip irrigation is the efficient irrigation system which has found great use in orchards, value crops, etc. It is advantageous where shortage of irrigation water and poor quality of the water are the constraints in crop production. With drip irrigation water can be applied very precisely and frequently. It is an effective method to manipulate growth and production and record yields can be obtained. A subsurface drip irrigation system has the capability of applying sufficient water to meet the evaporative demand of the crop on a daily basis. This promotes maximum growth while minimizing any stress resulting from an inadequate supply of soil moisture. Although, the installation of drip irrigation systems is expensive, its advantages can help in the return of investment to some extent in terms of yield and quality of cotton. The objective of the present study was to study the performance of different planting methods in drip irrigation systems for yield and its components in American cotton (Gossypium hirsutum L.).

Material and methods

The experiment was conducted at Punjab Agricultural University, Regional Station, Abohar during summer 2006 to study the impact of drip irrigation along with different planting patterns on seed cotton yield, its components and water use efficiency of the crop. The trial comprised of following 12 treatments:

1. Drip irrigation with lateral in each row and 0.6 ETc

2. Drip irrigation with lateral in each row and 0.8 ETc

3. Drip irrigation with lateral in each row and 1.0 ETc

4. Drip irrigation with lateral in paired rows and 0.6 ETc

5. Drip irrigation with lateral in paired rows and 0.8 ETc

6. Drip irrigation with lateral in paired rows and 1.0 ETc

7. Drip irrigation with lateral in paired rows and every third row missing; and 0.6 ETc

8. Drip irrigation with lateral in paired rows and every third row missing; and 0.8 ETc

9. Drip irrigation with lateral in paired rows and every third row missing; and 1.0 ETc

10. Flood irrigation at 0.6 ETc

11. Flood irrigation at 0.8 ETc

12. Flood irrigation at 1.0 ETc

Approved Bt cotton hybrid MRC 6304 was used in this experiment and was sown after applying pre-sown irrigation in the whole field in a split plot design with four replications on 12.5.06. Each treatment was accommodated in rows of m. Rows were kept apart by 67.5 cm while plant to plant distance was maintained at 75 cm. The recommended dose of fertilizer was applied. The plant population was maintained in all the plots. In the system, where every 3^rd row was skipped, the plant population was maintained by increasing the number of plants in each row (decreasing the plant to plant population), so as to eliminate the factor of plant population in determining the seed cotton yield. The observations were recorded on plant height, number of bolls per plant, boll weight (g) seed index (g), seed cotton yield and ginning out turn. The standard statistical procedures were followed for analyzing the mean data.

Results

The results of the experiment showed that the differences in plant stand for different treatments were non-significant as the sowing was done after applying pre-sown irrigation in all the plots uniformly. Growth of the cotton crop in terms of plant height were maximum in the plots where drip irrigation was supplied with lateral in each row at 1.0 ETc (160.5 cm) and was significantly better than all the irrigation levels in flood irrigation system (Table 1). It had non-significant differences when compared with lower irrigation levels in the same system and with 0.8 and 1.0 ETc levels of the drip irrigation system with lateral in paired rows. Amongst yield parameters, seed index (100-seed weight) and boll weight had non-significant differences for different treatments. While, bolls per plant were maximum in treatment with drip laterals in each row at 1.0 ETc level (53.7) and differed non-significantly with 0.8 ETc levels in same system and 0.8 and 1.0 ETc level in the drip system with lateral in paired rows. While comparing with flood system, both drip with lateral in each row and paired rows were significantly better at all the levels of irrigation water. Ginning out turn did not have significant differences for different treatments. The maximum seed cotton yield per plant was found in drip system with lateral in paired row at 1.0 ETc. However, seed cotton yield per plant at different levels of irrigation water levels within the same system were non-significant in all the drip systems, while in flood system there was significant increase in seed cotton yield per plant from 0.6 to 1.0 ETc level. This implies that even lower amount of water in drip irrigation system can help in achieving similar yields. Seed cotton yield was found to be maximum (4259 kg/ha) in drip system with lateral in each row at 1.0 ETc level followed by drip system with lateral in paired rows at 0.8 ETc level (4122 kg/ha) and significantly lower yields were obtained in 0.6 ETc level in drip system with lateral in each row and paired row; 0.6 and 0.8 ETc levels in drip system where 3^rd row was skipped and same levels in flood system. In other way, while comparing different drip systems at same irrigation levels, it was found that all the systems produced significantly similar seed cotton yield at 1.0 ETc level, while at 0.8 ETc level, seed cotton yield was significantly higher in drip with lateral in paired row and with lateral in each row. However, considering the economy of both the systems, drip system with lateral in paired rows can be more beneficial. Results of Mussaddak and George (2001) study revealed that fertigation of cotton improved seed cotton yield, dry matter yield, earliness and, in some cases, lint properties. They also found that under drip fertigation, between 35-55% of irrigation water was saved compared with surface-irrigated cotton grown under the same conditions. Seed cotton yield of the fertigated-cotton increased by more than 50% in some cases compared with that of the surface-irrigated cotton.

Water Use Efficiency (WUE), a parameter which determines the production of crop per hectare per mm of water applied, was significantly higher in drip system with lateral in each row and with lateral in paired rows at all levels of irrigation water than the flood irrigation system. WUE was higher at 0.6 ETc levels (Table 1), where lowest amount of irrigation water was applied, whereas at this level, seed cotton yield tended to decrease significantly as compared to 0.8 and 1.0 ETc levels in all the systems. While comparing WUE of 0.8 and 1.0 ETc levels of all the systems where yield levels were non-significant, WUE was significantly higher in 0.8 ETc levels. When drip systems with lateral in each row and with laterals in paired rows were compared, both showed similar trend in WUE with irrigation levels and had non-significant differences when compared at similar irrigation levels.

Therefore, the drip irrigation system with laterals in paired rows at 0.8 ETc levels can be used for maximizing yield without ignoring the water use efficiency of the system.

References

Mussaddak, Janat and George, Somi. 2001. Performance of cotton crop grown under surface irrigation and drip fertigation. I. Seed cotton yield, dry matter production, and lint properties. Communications in Soil Sci. Plant Anal. 32: 3045-3061

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Table 1: Effect of different irrigation systems and irrigation levels on growth and yield parameters

Treatments	Plant stand	Plant height (cm)	Seed index (g)	Boll weight (g)	Bolls/ plant	Seed cotton yield/ plant	GOT (%)	Seed cotton yield (kg/ha)	Water use (mm)	WUE (kg/ha/mm)
T1	96.0	150.8	8.60	3.97	36.1	183.2	33.4	3595	176.5	20.37
T2	93.7	153.7	9.38	4.39	50.8	198.2	35.4	4029	235.4	17.11
T3	92.7	160.5	9.65	4.50	53.7	209.1	33.6	4259	294.2	14.48
T4	92.3	140.9	8.90	4.17	44.7	181.2	35.7	3570	176.5	20.23
T5	94.0	151.7	9.03	4.09	46.5	206.7	33.4	4122	235.4	17.51
T6	92.7	155.8	8.39	4.30	53.3	217.8	36.7	4033	294.2	13.71
T7	92.3	138.1	8.30	3.78	40.9	167.8	38.4	3449	176.5	19.54
T8	93.3	140.6	8.06	4.30	42.2	182.8	33.1	3555	235.4	15.10
T9	92.7	141.6	8.17	3.73	44.9	197.1	34.3	3821	294.2	12.99
T10	92.0	125.8	9.36	4.03	24.5	158.2	34.5	3261	197.5	16.51
T11	92.7	136.1	8.66	4.08	32.8	180.7	35.1	3539	263.4	13.44
T12	91.7	139.4	9.14	4.09	40.3	197.8	33.5	3906	329.2	11.87
CD (5%)	NS	10.4	NS	NS	11.2	31.0	NS	401	-	1.94
CV	4.16	4.24	11.18	8.96	15.58	9.63	6.46	6.29	-	7.14

T1: Drip irrigation with lateral in each row and 0.6 Etc; T2:Drip irrigation with lateral in each row and 0.8 ETc

T3: Drip irrigation with lateral in each row and 1.0 Etc; T4: Drip irrigation with lateral in paired rows and 0.6 Etc

T5: Drip irrigation with lateral in paired rows and 0.8 Etc; T6: Drip irrigation with lateral in paired rows and 1.0 ETc

T7: Drip irrigation with lateral in paired rows and every third row missing; and 0.6 Etc;

T8: Drip irrigation with lateral in paired rows and every third row missing; and 0.8 ETc

T9: Drip irrigation with lateral in paired rows and every third row missing; and 1.0 Etc; T10: Flood irrigation at 0.6 ETc

T11: Flood irrigation at 0.8 Etc; T12: Flood irrigation at 1.0 ETc

Efficacy of fertilizer application in cotton under drip and flood irrigation system

Manpreet Singh¹, R.K. Gumber¹, A.S. Brar², and Mukesh Siag²

¹Punjab Agricultural University, Regional Station, Abohar, India; ²Punjab Agricultural University, Ludhiana

ABSTRACT

Fertilizer application method is one of the important factors in addition to fertilizer dose amongst different agronomic practices, which influence the growth and yield of cotton considerably. Under drip irrigation system, Nitrogen Use Efficiency (NUE) tends to increase if applied through drip system as compared with flood irrigation system. An experiment was conducted at Punjab Agricultural University, Regional Station, Abohar to compare the fertilizer application in two irrigation systems and to find out the optimum fertilizer dose for higher yields under drip irrigation. Field trials comprised of four treatments, i.e., 50% recommended N through drip, 75% N through drip and 100% N in drip and 100% through broadcasting in flood system. In these treatments, the fertilizer through drip was applied in four equal split doses, while in flood irrigation system fertilizer was applied in two equal split doses. Preliminary results in this study showed that 75 % N through drip produced maximum seed cotton yield. Although all the treatments where N was applied through drip produced at par yields but these were significantly higher than the yield produced by 100 % N through flood system. 50% N, 75% N and 100% N through drip produced 15.6, 22.7 and 14.3 per cent higher seed cotton yield over the treatment where recommended dose of N was applied through broadcasting in flood irrigation system. It pertains to the fact that NUE definitely increases when applied through drip in four split doses, which helps in increasing yield levels with lesser amount of fertilizer.

Introduction

Nitrogen fertilizer and irrigation methods are the key factors for yield increase and yield quality improvement. With good management of these two factors, both production and protection can be attained simultaneously. The fertilizer application is one of the major agronomic factors for obtaining good yields. Due to the cultivation of high fertilizer demanding BT cotton on the large areas in Punjab; it is necessary to apply the fertilizer in such a way to increase its efficiency and the effect in producing good yields. Micro-irrigation systems and fertigation -- which is the application of fertilizers through an irrigation system -- have many benefits as they help to control water and nutrients in the root-zone, saving labor and equipment costs. Moreover, with drip irrigation, all nutrients can be applied whenever needed. Thus, keeping in view the above facts, an experiment was conducted to estimate the optimum fertilizer dose, when it is applied through drip system.

Material and methods

An experiment was conducted at Punjab Agricultural University, Regional Station, Abohar to test the efficiency of N fertilizer applied through drip irrigation system as compared to the flood irrigation. The sowing of Bt cotton hybrid MRC 6304 was done in a randomized block design with three replications on 12.5.06. The recommended row to row and plant to plant spacing of 67.5 cm x 75 cm was used. The dose of N fertilizer and the method of application differed as per the treatment. Phosphorus was applied in recommended dose in the form of DAP at the time of sowing. The drip system was laid out with laterals provided in each row of the crop. The Nitrogen was supplied to the crop as recommended in two split doses by broadcasting in the flood irrigation system, while in the drip system, the N was supplied in four equal split doses through drip system starting with first dose at thinning and the remaining three doses at 15 days interval. The trial comprised of four treatments namely 50% of recommended dose of Nitrogen (RDN) through drip system; 75% RDN through drip; 100% RDN through drip; and 100% RDN through broadcasting in Flood irrigation system. The observations were recorded on plant height, number of bolls per plant, boll weight (g) seed index (g), seed cotton yield and ginning out turn, In addition, Nitrogen Use Efficiency was also calculated. The standard statistical procedures were followed for analyzing the mean data.

Results

The results (Table 1) showed that the growth of cotton in terms of plant height was significantly influenced when the N was applied through drip. 100% RDN in drip recorded maximum plant height but was at par with the treatments 50% RDN and 75% RDN applied through drip system, and significantly higher than the plant height obtained with 100% N applied by broadcasting in flood irrigated cotton crop. This may be due to the fact that N was used efficiently by the crop when applied through drip system as compared to the traditional method of broadcasting.

Also yield characters like boll weight and seed cotton yield per plant were significantly higher in the treatment where 75% of RDN was applied through drip system as compared to the 100% RDN broadcasted in flood irrigation system, while seed cotton yield per plant was non-significant in the three treatments where N was applied though drip system. Even 50% of RDN when applied through drip system produced significantly higher seed cotton yield than the 100% RDN applied by broadcasting in flood irrigation system. GOT was found to have non-significant differences for different treatments. While comparing Nitrogen Use Efficiency (NUE) of different treatments, it was observed that maximum NUE was obtained in the treatment with the lowest amount of supplied N and was significantly higher than all other treatments.

These results suggests that while using drip irrigation system, even 50% of the recommended Nitrogen fertilizer if applied through drip system, can produce higher seed cotton yield as compared to 100% of the Nitrogen applied by broadcasting in flood irrigation system, which is due to the increased nitrogen use efficiency by the crop when the fertilizer is applied in four split doses and that too dissolved in water near the root zone through drip irrigation system.

Table 1: Effect of dose and method of fertilizer application on growth and yield parameters of cotton

Treatments	Plant stand	Plant height (cm)	Seed index (g)	Boll weight (g)	Bolls/ plant	Seed cotton yield/ plant	GOT (%)	Seed cotton yield (kg/ha)	Nitrogen Use Efficiency
50 % RDN through drip	90.8	150.9	8.75	4.08	44.8	211.6	35.23	4130	55.07
75 % RDN through drip	92.8	150.4	8.93	4.59	41.4	219.5	34.61	4385	38.98
100 % RDN through drip	92.2	153.6	8.81	4.41	40.4	209.5	34.42	4084	27.23
100 % RDN through flood system	86.8	127.1	8.49	3.95	40.9	181.3	33.34	3574	23.82
CD (5%)	NS	8.2	NS	0.43	NS	18.7	NS	377	3.06
CV	6.74	4.09	6.98	7.40	19.40	6.61	4.89	6.77	6.12