Browsing by Author "Ratheesh Narayanan, M.K."

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    Variations in nut yield of coconut and dry spell in different agro-climatic zones of lndia
    (2007-09) Naresh Kumar, S.; Rajagopal, V.; Siju Thomas, T.; Vinu K. Cherian; Ratheesh Narayanan, M.K.; Ananda, K.S.; Nagawekar, D.D.; Hanumanthappa, M.; Vincent, S.; Srinivasulu, B.
    Coconut is the major perennial crop in coastal areas of lndia. It is mainly grown under rainfed conditions in areas of high rainfall. However, these plantations face summer drought situations as the rainfall distribution is restricted to only 4 to 5 months a year, leaving remaining period as dry. The objective of the study is to quantify the dry spell and to deduce the influence of rainfall and dry spell on the nut yield in major coconut growing areas situated in different agro-climatic zones of India. viz., western coastal area - hot sub-humid per-humid (represented by Kasaragod in Kerala and Ratnagiri in Maharashtra), Western Ghats - hot sub-humid per-humid (represented by Kidu in Karnataka); hot semi-arid (represented by Arsikere in Karnataka); and eastern coastal plains - hot subhumid (represented by Veppankulam in Tamil Nadu and Ambajipeta in Andhra Pradesh). Variation in annual rainfall was from a maximum of 3337.7 mm (Kasaragod) to a minimum of 718.23 mm (Arsikere). Dry spell was longer in Ratnagiri (216 days) and Arsikere (202 days), and shorter at Kidu (146 days). The annual nut yield under rainfed conditions varied from 68 (Ambajipeta) and 66 (Kasaragod) to 41 (Arisekere) and 30 (Kidu). Impact of variations in dry spell on nut yield was discernible from the study. In view of the long duration (44 months) between the inflorescence initiation to nut maturation, the occurrence of dry spell in any one year would affect the yield for the subsequent three to four years. It can be inferred that the longer dry spell affects the nut yield for next four years to follow with stronger impact on fourth year, irrespective of the total rainfall.
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    Weather data based descriptive models for prediction of coconut yield in different agro-climatic zones of India
    (2009-03) Naresh Kumar, S.; Rajagopal, V.; Cherian, V.K.; Siju Thomas, T.; Sreenivasulu, B.; Nagvekar, D.D.; Hanumanthappa, M.; Bhaskaran, R.; Vijayakumar, K.; Ratheesh Narayanan, M.K.; Amarnath, C.H.
    Weather variables play an important role in determining the coconut palm growth, development and yield. The influence of weather on nut yield in coconut starts from inflorescence initiation and lasts till nut maturity (44 months). Historical data on weather variables and coconut nut yield from different agro-climatic zones viz., Western coastal area – hot sub-humid-per-humid (Kasaragod – Kerala; Ratnagiri – Maharastra), hot semi-arid (Arisikere – Karnataka) and Eastern coastal plains- hot sub-humid (Veppankulam- Tamil Nadu; Ambajipeta- Andhra Pradesh) of India were used for developing models for prediction of coconut yield. The prediction models with 3- and 4-year lag had high R2 values. The models differed for usage of parameters in different agro-climatic zones, indicating the relative importance of these parameters in respective conditions for realizing the nut yield in coconut. Interestingly, the parameters used in models for western coastal area – hot sub-humid-per-humid are temperature and relative humidity, as indicated even in the classification of these areas. Models were verified for 2 years and prediction of yield during 1998-99 and 1999-2000 within 10% confidence level validated these models. The study indicates that the relative humidity and temperature play important role during the ontogeny of inflorescence and nut development. The descriptive models, developed based on weather data, can be used for prediction of coconut yield two to four years in advance with in acceptable range of accuracy. The yields to be realized can be bracketed within predicted range obtained from models using one, two, three, and four year lags. These models can also be used for prediction of coconut nut yield in the situations similar to those in the present study.