MSc

The study entitled “Enhancing nutrient use efficiency through nano-DAP in
upland rice (Oryza sativa L.)” was conducted during 2021-2023 at College of
Agriculture, Vellayani. The main objectives of the study were to evaluate foliar applied
DAP and nano-DAP on growth, nutrient use efficiency, yield and working out the
economics in upland rice.
The study was carried out in randomized block design with (4×2)+1 treatments
replicated thrice at Instructional Farm from November 2022 to February 2023. The
treatments included two factors, levels of recommended dose of nutrients (N) with four
levels of N and P (n1: 100 per cent N and P; n2: 75 per cent N and P; n3: 50 per cent N
and P and n4: 25 per cent N and P); and two levels of foliar fertilizers (F) applied at AT
(active tillering) and PI (panicle initiation) stages (f1: 2 per cent DAP and f2: 0.2 per
cent nano-DAP), compared against KAU POP as control. The rice variety used for the
study was Prathyasa and nutrient recommendation followed was 60:30:30 kg NPK ha-1
as per the KAU POP.
The results of the study indicated that the levels of recommended dose of nutrients
had significant effect on growth attributes of rice. Significantly taller plants were
recorded in n1 and was on par with n2 and n3 at flowering stage. The highest number of
tillers per square metre, leaf area per hill and LAI were recorded in n1 at AT (663.33
tillers m-2
, 593.58 cm2
, 3.96 respectively), PI (739.00 tillers m-2
, 1003.88 cm2
, 6.69
respectively) and flowering (683.00 tillers m-2
, 1140.90 cm2
, 7.61 respectively) stages.
Leaf area duration (LAD) during AT to PI (79.87 days), PI to flowering (107.24 days),
flag leaf area per hill (61.23 cm2
) and total dry matter production (8852 kg ha-1
) were
also higher in n1. Among foliar fertilizers, the highest leaf area per hill and LAI were
obtained in f1 at PI and flowering stages. The longest LAD during PI to flowering stages,
and flag leaf area per hill were also recorded in f1. Considering the interaction, n1f1
resulted in significantly higher leaf area, flag leaf area per hill, and total dry matter
production. Treatments are significantly higher than that of control with respect to
growth attributes in rice.
The productive tillers per square metre (513.17 and 455.75), number of grains
per panicle (105.75 and 95.56), grain yield (4.91 t ha-1
and 4.46 t ha-1
) and straw yield
(5.73 t ha-1
and 5.24 t ha-1
) were observed to be the highest in n1 and f1 respectively.
Significantly higher harvest index (0.467) was noticed in n2 which was on par with n1.
The lowest sterility percentage was recorded in f1. The combination, n1f1 was
significantly superior in producing the higher productive tillers per square metre, grains
per panicle, grain and straw yield. However, the highest harvest index was obtained in
n2f2 (0.472).
Significantly higher leaf N and P contents were recorded in n1 for both AT and
PI stages. At harvest stage, grain N content was higher in n1 which was on par with n2.
The highest straw N content and grain P content were recorded in n1. The highest straw
P content was in n2 and straw K content was higher in n1 which was on par with n2 and
n3. Among foliar fertilizers, f1 resulted in higher leaf N content at PI stage, grain P and
K contents and straw P content at harvest stage. Significantly higher leaf N content at
PI, grain and straw P contents and grain K content at harvest stage were recorded in f1.
Considering the interaction, n1f1 had significantly higher leaf N and P contents at AT
and PI stages but was on par with n1f2. At harvest stage, higher grain P content was with
n1f1 and n1f2. However, straw P content was higher in n2f2 and n3f1. Straw K content was
higher in n1f2 but was on par with n2f1. Crude protein content was higher in n1, was on
par with n2 and n3.
The treatment, n1 resulted in significantly higher N (130.02 kg ha-1
), P (32.31 kg
ha-1
) and K uptake (145.32 kg ha-1
) but was comparable with n2 for K uptake. Foliar
fertilizers had significant effect on P uptake (26.05 kg ha-1
) with the highest value in f1.
When significantly higher N uptake of 136.69 kg ha-1 was recorded in n1f1, the
interaction n2f1 produced the highest K uptake. On comparing treatments with control,
n1f1 recorded significantly higher N, P, K uptake. When the highest agronomic
efficiency (AE) and physiological efficiency (PE) of N and P were recorded in n2, the
highest apparent recovery efficiency (ARE) of N was obtained in n4, and that of P in n3.
The treatment f1 resulted in the highest AE of N (36.86 kg kg-1
), and PE of N (19.24 kg
kg-1
) and P (73.24 kg kg-1
). However, higher ARE of P (94.74%) was recorded in f2.
Considering the interaction, PE of N was significantly higher with n3f1 whereas PE of
P was the highest with n2f1. Significantly higher ARE of N and P were obtained in n3f2.
Significantly higher chlorophyll contents at AT and PI stages were observed in
n1. Among foliar fertilizers, f1 had the highest value at PI stage. Soil available N (263.58
kg ha-1
) was higher in n1. The highest available P was recorded with n2 (106.82 kg
ha-1
), f1 (103.92 kg ha-1
) and n2f1 (117.86 kg ha-1
).
Significantly higher net income and B:C ratio were recorded in n1 (₹ 39,497
ha-1
, 1.21), f1 (₹ 21,633 ha-1
, 1.12) and n1f1 (₹ 47,124 ha-1
, 1.26).
From the study it could be concluded that, soil application of 100 per cent
recommended dose of N (60 kg ha-1
), P (30 kg ha-1
) and K (30 kg ha-1
) supplemented
with foliar application of 2 per cent DAP (Diammonium phosphate) at active tillering
and panicle initiation stages were effective for enhancing growth, productivity, nutrient
use efficiency and economics in upland rice