Crop Weather Interaction in Potato in South Bengal Plains

Introduction

In the Gangetic plains of Bengal, appreciable contributions in research have been made on a few crop plants which include rice, jute, wheat, mustard and few pulses. The assessment of weather on these crops remains incomplete. Potato is a new entrant in this arena of study. The growth of potato plant and its tubers depends largely on weather factors particularly temperature, solar radiation and day length. The potato is surface feeder. The root system is usually confined to the top layers of the soil (up to 30 cm). Therefore, nutrient content within the top layers of the soil principally regulates the growth of haulm as well as tuber. Soil temperature influences the uptake of nutrients and water from the top soil layer. Growth of the buds starts after planting of the tuber, which is largely dependent on temperature. At 15 °C or above, the apical sprout grows faster to restrict the other buds at a small size (Goodwin, 1967). Under non favourable temperatures, many buds continue to grow for a longer period. The dominant sprout is maintained by storing the tuber under favourable and sub-favourable temperatures. Therefore, it is possible to have pre-determined population by manipulating the storage temperature (Moorby & Milthorpe, 1975). The rate of dry weight gain of sprout in single-sprout tubers remains constant over a prolonged period irrespective of temperature.

The crop growth period may be divided into three distinct phases:

• 1.

  Planting to establishment of sprouts

• 2.

  The first phase of autotrophic growth when biomass accumulation in haulm is prominent

• 3.

  Tuber growth period comprising of the translocation of photosynthates with the gradual senescence of haulms

In the Gangetic plains of West Bengal, potato cultivation is generally confined to several districts scattered on both the banks of the Ganges. The winter here is mild and short. The winter creeps in with the withdrawal of the south-west monsoons. This plain welcomes the cool north east continental wind from the end of October. The growing season of potato is thus restricted to November to February. The potato must be planted within 15th of February for better yield. The present scenario is different due to weather variability. The late onset and concomitant delayed withdrawal of monsoons impede land preparation for potato. The temperature doesn’t drop even during December. Under this changing scenario, the present two year field experiment has been performed to understand the crop weather interaction in potato.

The experiments were carried out during the winter seasons of 2010-11 and 2011-12 at Kalyani, B.C.K.V. (Lat: 22°58’ N and Long: 88°32’ E). The experimental site is located in the eastern bank of the river Ganges of Nadia district. The district is famous for vegetable and potato cultivation. The experimental site falls under tropical sub-humid climate and experiences three distinct seasons. The annual rainfall is approximately 1500 mm, 80% of which occurs during monsoons.

In the present chapter, impact of temperature humidity and rainfall on the growth and the yield of the crop were investigated. The crop was exposed to variable weather condition by planting it on five different dates viz. D1- 15th November, D2- 22nd November, D3- 29th November, D4- 6th December and D5- 13th December. Macro climatic analysis of maximum and minimum temperatures, relative humidity and rainfall were done. The weather data were collected from the meteorological observatory adjacent to the experimental site. The leaf area index (LAI) of the crop was measured using LAI 220 Plant Canopy Analyzer (LI-COR). Crop Growth Rate (CGR) indicates the rate at which the crop is growing and is expressed as g of dry matter produced per day.