SPATIAL NUTRIENT VARIABILITY: INFLUENCE ON PETIOLE NUTRIENT CONTENT AND GRAPE YIELD
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Date
2018-08
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University of Horticultural Sciences, Bagalkot
Abstract
An experiment was carried out in Bagalkot taluk, Karnataka to assess the
spatial nutrient variability and its influence on petiole nutrient content and grape yield
during 2017-18. A compact block of 5 acres planted at 3 m × 1.5 m with convenient
grids (187) of 100 m2 (10 m × 10 m). Soil (0–15 cm) and petiole samples collected
after pruning (October) were analyzed and subjected to statistical analysis after
grouping the data by K-means clustering technique.
The spatial variability as measured by Moran Index showed distinct variation
in maps for soil reaction (0.47), soil organic carbon (0.66), available phosphorus
(0.59), potassium (0.60), magnesium (0.40) and sulphur (0.70). However, the spatial
variability maps for remaining parameters did not show variation indicating no
specific segregation into meaningful clusters in the maps. The cluster-I recorded
significantly higher soil organic carbon, available nitrogen, phosphorus, potassium,
sulphur, iron and zinc whereas cluster-II showed significantly higher available
magnesium. However, soil reaction and available calcium were found significantly
higher in cluster-III compared to cluster-I and cluster-II. Further, the available
manganese and copper remained non-significant and inconclusive amongst the
clusters.
The petiole analysis revealed that cluster-I found significantly higher in
nitrogen, phosphorus, potassium and iron while in cluster-II, sulphur and manganese
were found significantly higher. However, cluster-III recorded significantly higher
calcium and magnesium content. Further, zinc and copper content among the different
clusters remained non-significant over all the clusters.
The Normalized Difference Vegetation Index (NDVI) showed higher values in
cluster-I and cluster-II compared to cluster-III. The recorded SPAD readings (25 days
interval) did not show any significant difference among different clusters. The fruit
yield of grapes indicated significant and positive correlation with EC, available N, P,
K, S, Mn and Cu whereas available Ca, Mg and Fe recorded significant negative
correlation. However, the grapes yield showed significant and positive correlation
with petiole N, P, K, S, Fe and Mn. On the contrary significant and negative
correlation is observed with petiole Ca and Mg. Multiple regression equation revealed
a significant positive contribution of soil organic carbon, available sulphur, available
phosphorus, soil reaction, electrical conductivity as well as petiole sulphur and
potassium. On the contrary, available magnesium, calcium and iron showed negative
contribution to yield.