IMPORTANCE OF DETERMINING THE NUTRITIONAL STATUS
1. INTRODUCTION Cultivation
(PHASEOLUS VULGARIS L.)
T. N. SHIVANANDA AND B. R. V. IYENGAR
Isotope Laboratory, Division of Soil Science, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore 560 089 India.
E-mail: [email protected] or [email protected]
1. INTRODUCTION
contributing to 23.46 per cent of total production. Although India stands first in area and production among Asian countries, the productivity is poor. The produc-tivity in India is 460 kg/ha, which is far behind Lebanon (2400); Azerbaijan (2007);
China (1800); Japan (1707); Indonesia (1607) and Iran (1576) amongst Asian countries. Further, the productivity in India is low when compared to productivity (kg/ha) of other continents or sub-continents such as Asia (671); Africa (633); North Central America (1006); South America (736); Europe (1339); Australia (911) and of world (729) (Anon, 1999a). French bean is cultivated in India in an area of 1.48 lakh hectares with a production of 4.2 lakh metric tons (Anon, 1997a).
1.2. Soil
French bean can be successfully cultivated throughout the year in warmer regions of India except in northern parts of India where the weather is severe in both summer (going up to 40 °C) and winter (touching zero). It is sensitive to frost. The fruit set is severely hampered at temperatures above 30 °C. It loves to grow on sandy loams where the soil is loose and root penetration is easy. The desirable pH range of soil for optimum production is 5.5 to 6.8. However Choudhury (1967) opined that optimum pH for F. bean cultivation is pH 5.5 to 6.0 on sandy or sandy loam soils.
The crop is too sensitive to water stagnation and to extreme acidic or alkaline soil conditions. The crop quality will be severely affected if grown on problematic soils due to nutrient imbalance. The seed germination is also found affected on heavy soils. Hence loamy soils are preferred for profitable cultivation.
1.3. Season
Among beans all the three groups are noticed, namely long day, short day and day neutral groups. Most of the French bean varieties are day neutral (Choudhury, 1967).
Since they are photo insensitive they are more or less cultivated throughout the year.
However it is cultivated to a limited extent in high rainfall areas and as well in north India between January and March where the temperature is optimum for the plant growth. It is more suited to the areas having 1000 to 2000 meters above mean sea level receiving rainfall of about 70 cm per annum.
1.4. Nutrients
Although all 16 essential nutrients are required in appropriate proportion for optimum pod yield, NPK nutrients are required in major quantities. It is found that it responds very well to applied nitrogen and phosphates on Indian soils. However it is reported that in UK it responds well to applied N rather than applied P. This may be probably due to variations in nutrient reserves in soils. Further it is reported that a ratio of 3:2:1 for application of NPK may be appropriate based on previous several years experience (Gane et al., 1975).
1.5. Nodulation
Nodulation is seldom seen in F. bean. The nodulation is caused by Rhizobium phaseoli in French bean, which is specific to the crop. Due to sparse or little nodu-lation, the crop depends largely on applied N for optimum pod yields. For this reason the crop responds well to applied nitrogen. Good response has been obtained from as low as 25 kg/ha for Delhi (Arya et al., 1999) to 120 kg/ha in Uttar Pradesh (Singh et al., 1996; Tewari and Singh, 2000). Application of well decomposed farm yard manure encouraged root nodulation. The root development was extensive in FYM applied plants than the fertilizers applied plants (Shivananda et al., 1998). Research work is in progress in India and as well in UK also (Gane et al., 1975) to evolve varieties responsive to root nodulation. There is limited success but more is yet to come.
1.6. Nutritive value
French bean is a nutritive vegetable that supplies protein (24 to 30 percent) and a good source of minerals such as calcium (50); phosphorus (28); iron (1.7) carotene (132) thiamine (0.08) riboflavin (0.06) and vitamin (24) mg/100 g of edible pods (Gopalan et al., 1982). Parthasarathy (1986) analysed edible green pods and found that 100g beans contain 91.4 g moisture, 1.7 g protein, 0.1 g fat, 4.5 g carbohydrates, 1.8 g fiber, 0.5 g minerals. Among minerals it was found that it contained 50 mg calcium, 28 mg phosphorus, 1.7 mg iron, 129 mg potassium, 37 mg sulphur, 4.3 mg sodium and 0.21 mg copper. Also he reported that 100 g beans contain 221 IU vitamin A, 0.08 mg thiamine, 0.06 mg riboflavine, 11.0 mg vitamin C and 0.3 mg nicotinic acid. Further it is reported that French bean is a good source of amino acids such as arginine, histidine, lysine, tryptophane, phenyl alanine, tyrosine, methionine, cysteine, threonine, leucine, isoleucine and valine (Kelley, 1972). For these reasons it is regarded as an important delicious vegetable. The variations in the values reported may be due to reporting from different varieties and sampling at different stages. Hence the values reported from one another are different. French bean is also considered as a medicinal vegetable. The beans are considered anti-diabetic and cure for bladder, burns, cardiac carminative, depurative diarrhoea, diuretic, dropsy, dysentery, eczema emollient, hiccups, itchy, kidney resolvent, rheumatism, sciatica and tenesmus (Duke, 1981).
1.7. Constraints in production
There are several constraints in the production of French bean. These constraints can be classified in to broadly two groups. 1. Lack of varieties suitable to specific soil, climate, export market, process market etc. 2. Lack of appropriate production technology. As a result of these implications the productivity of the crop in India is far below than the anticipated. To increase the productivity of French bean there is a need for coordinated efforts of scientists from various disciplines. Presently the emphasis of the plant breeders is to evolve a variety for higher yields. Since
the crop is susceptible to few diseases such as rust or rot. The breeders are concentrated in evolving a variety resistant/tolerant/less susceptible to the disease.
But there is no concern among breeders – plant nutrition scientists combined to evolve a variety for N or P stress conditions. The deficiency of these two nutri-ents will continue to daunt our productivity of almost all agricultural crops.
The concern for soil health has not gained momentum as much as it has gained with respect to plant health. If the soil health is not cared for, probably plant health deteriorates at much faster rate. Hence there is a need to re-orient strategies to strengthen plant breeding programs to accommodate plant nutrition as priority. Since Indian soils are starved of N and P mainly, there is a need to screen varieties for such soils. Although the genetic base for the crop is limited there is always scope for increasing the genetic base through exchange programs. For this purpose there is a need to develop a data base to be used by plant breeders where all the infor-mation is available.
The second biggest problem with respect to production technology is lack of
‘appropriate’ technology. Although recommendations for nutrients (mostly NPK) have been worked out the quantities have been too large. Re-visiting the problem to reduce the fertilizers is demanding since the crop duration is too short and the economic viability of growers also inhibits to apply such large quantities. The question that needs immediate answer is how to increase the utilization of applied fertilizer? By any technique if the utilization efficiency could be increased, can we reduce the fertilizer input without compromising yield? These are some of the intriguing questions that demand immediate attention of soil scientists/agrono-mists. In this chapter sincere efforts are made to pool the information on these above issues and relevant points are discussed.
2. VARIETIES